journal of applied chemical research · 6 journal of applied chemical research, 19, 4 (2011)...

Journal of Applied Chemical Research(Index in ISC)

Editor- in- Chief

Ali Mahmoudi, Ph.D. (Associate Prof., Islamic Azad University, Karaj branch, Iran)

Managing Editor

Abbas Ahmadi, Ph.D. (Associate Prof., Islamic Azad University, Karaj branch, Iran)

Regional Editor

Bita Mohtat, Ph.D. (Associate Prof., Islamic Azad University, Karaj branch, Iran)

Editorial Board

Saeed Dehghanpour, Ph.D. (Associate Prof., Alzahra University, Tehran, Iran)

Lida Fotouhi, Ph.D. (Prof., Alzahra University, Tehran, Iran)

Nader Zabarjad, Ph.D. (Associate Prof., Islamic Azad University, Central branch, Iran)

Mahmoud Sharifimoghadam, Ph.D. (Prof., Tarbiatemoalem University, Tehran, Iran)

Khodadad Nazari, Ph.D. (Assistance Prof., Petroleum Research Institute, Tehran, Iran)

Mohsen Daneshtalab, Ph.D. (Prof., Memorial University, Canada)

Masayuki Sato, Ph.D. (Prof., Shizoka University, Japan)

R.K.Agarwall, Ph.D. (Prof., Singh University, India)

Surendra Prasad, Ph.D. (Prof., South Pacific Univesity, Fiji)

Literal Editor

Ahmah Jahan Latibari, Ph.D. (Associate Prof.)

Volume 19, No. 4, 2011

Address

Faculty of Science, Islamic Azad University, Karaj branch

P.O. Box: 31485-313, Karaj, Iran (www.jacr.kiau.ac.ir )

Journal of Applied Chemical Research, 19, 4 (2011)2

Content of issue Pages

1. A Theoretical Study of 1H-NMR Parameters in the Real Crystalline Structure of Iminopyridine ComplexesH. Nasiri1, H. Behzadi2, M.R. Talei Bavil Olyai*2, R. Rezaeian1

1Department of Chemistry, Faculty of Science. Islamic Azad University, Karaj Branch, Karaj, Iran.2Department of Chemistry, Faculty of Technical and Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran.

7

2. Synthesis and Application of UV-Absorber Oxanilide Containing Monomers S. Baradaran Razaz1, N. Zabarjad-Shiraz*2, A. Afsharnia1, A. Ahmadi1, A. Mahmoudi1, M. Bayat3

1Department of Chemistry, Islamic Azad University, Karaj Branch, Karaj, Iran. 2Department of Chemistry, Islamic Azad University, Central Tehran Branch, Tehran, Iran. 3Department of Chemistry, Imam Khomeini University, Qazvin, Iran.

13

3. Synthesis, Spectroscopy Property and Luminescence Study of the Chelate Complexes of Europium with ß-diketone and its DerivativesM.H. Eshraghi*, S.M. khodaian, S. Ghadimi, S.M. Moosavi, B. MaddahFaculty of chemistry, Department of science, Emam Hossein University, Tehran, Iran.

18

4. Selective and Validated Spectrophotometric Methods for Determination of Acyclovir and Ganciclovir with 2, 4-DNP as ReagentT.Anil Kumar, B. M. Gurupadayya*, M.B. Rahul Reddy, M.V. Prudhvi RajuDepartment of pharmaceutical analysis, JSS College of Pharmacy, JSS University, India.

27

5. Analytical Technique for detection of Motor Gasoline Adulteration using Gas Chromatography-Detailed Hydrocarbon Analysis (DHA)J.Balakrishnan*, V.BalasubramanianDepartment of Chemistry, AMET University, India.

41

6. The Operating of the Niccolite Ore and Nickel Extraction of it by DMG in Ammoniacal mediaA. Abedi Department of Chemistry, Islamic Azad University, Tehran North Branch, Tehran, Iran.

48

7. Density Functional Theory Study of Magnesium Hydride Nano Clusters R. MajidiDepartment of Physics, Shahid Beheshti University, Evin, Tehran, Iran.

58

8. Molecular Mechanics Based Study on Molecular and Atomic Orbital of NickeloceneG. KhanDepartment of Physics, K. S. Saket, Post graduate college, Ayodhya-Faizabad, U.P., India.

66

Journal of Applied Chemical Research, 19, 4 (2011) 3

Journal of Applied Chemical Research (JACR) (Journal of Applied Chemistry, JAC, before) is published quarterly by Islamic Azad University (Karaj branch). Copyright is reserved by the University.

Aims and Scope JACR is an Iranian journal covering all fields of chemistry. JACR welcomes high quality original papers in English and Persian dealing with experimental and applied research related to all branches of chemistry .These includes the fields of analytical, inorganic, organic, physical and applied chemistry area. Review articles discussing specific areas of chemistry of current chemical importance are also published. Journal of Applied Chemical Research ensures visibility of your research results to all scientists (open access). You are kindly invited to submit your manuscript to this Journal. All contributions in the form of original papers or short communications will be peer reviewed and published free of charge after acceptance.

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JACR Editorial Board:Editor-in-Chief: Ali Mahmoudi, Ph.D.,Associate Prof., Department of Chemistry, Islamic Azad University, Karaj branch Karaj, Iran.Managing Editor:Abbas Ahmadi, Ph.D, Associate Prof., Department of Chemistry, Islamic Azad University, Karaj branch, Karaj, Iran.Regional Editors:BitaMohtat, Ph.D,Associate Prof., Department of Chemistry, Islamic Azad University, Karaj branch, Karaj, Iran.


Editorial Board:Saeed Dehghanpour, Ph.D., Associate Prof., Department of Chemistry, Alzahra University, Tehran, Iran.Khodadad Nazari, Ph.D., Assistance Prof., Petroleum Research Institute, Tehran, Iran.Lida Fotouhi, Ph.D., Prof., Department of Chemistry, Alzahra University, Tehran, Iran.Mahmoud Sharifimoghadam, Ph.D., Prof.Department of Chemistry, Tarbiatemoalem University, Tehran, Iran.Nader Zabarjad, Ph.D., Associate Prof., Department of Chemistry, Islamic Azad University, Central branch, Tehran, Iran.Mohsen Daneshtalab, Ph.D., Prof., Medicinal Chemistry and Pharmacognosy, School of Pharmacy, University of Memorial, Canada (Honorary member).Masayuki Sato, Ph.D., Prof., School of Pharmaceutical Sciences University of Shizuka (Honorary member).R.K.Agarwall, Ph.D.,Prof., Department of Chmistry, Singh University, India.Surendra Prasad,Prof., Department of Biological and Chmical Sciences, Thechnology and Environment, South Pacific (USP) University,Surva, fiji.

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Journal of Applied Chemical Research, 19, 4 (2011) 5

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Journal of Applied Chemical Research, 19, 4, 7-12 (2011)

Journal of App l ied Chemical Research

www.jacr.k iau.ac. i r

A Theoretical Study of 1H NMR Parameters in the Real Crystalline Structure of Iminopyridine Complexes

H. Nasiri1, H. Behzadi2, M.R. Talei Bavil Olyai2*, R. Rezaeian1 1Department of Chemistry, Faculty of Science Islamic Azad University, Karaj Branch, Karaj, Iran

2Department of Chemistry, Faculty of Technical and Engineering, Islamic Azad University South Tehran Branch, Tehran, Iran

(Received 15 May 2011; Final version received 10 Auguest 2011)

AbstractA computational study was carried out procedure was used to investigate the relationship between the 1H shielding tensors of iminopyridine ligand and its related complexes. The calculations were performed appliying the B3LYP method and 3-21G* standard basic set using the Gaussian 98 series of programs. The results showed that σ33 is the most affected due to the bonding of ligand and complexes and may be used as a probe to explain the bonding effect of different ions at iminopyridine complex.Keywords: Iminopyridine, Schiff base, GIAO, NMR, DFT calculations.

Introduction

A Schiff base or azomethine, is a functional

group that contains one carbon-nitrogen double

bond with the nitrogen atom connected to an aryl

or alkyl group but not hydrogen. Schiff bases

can be synthesized from an aromatic amine and

a carbonyl compound via nucleophilic addition.

The application of transition metal catalysts

to poly ethylene polymerization is currently

a desirabte subject of sustained interest [1-3].

Ziegler-Natta’s original work on AlR3 catalysis

of ethylene oligomerization has been focused

on group 4B transition metal catalyst systems

such as metallocenes [4], and half-metallocenes

[5-10]. Recently, transition metal catalyst

systems incorporating iminopyridine ligands,

and in particular the discovery of exceptionally

active catalysts based on iron and cobalt which

convert both ethylene and α-olefins to high

molecular weight polymers, have been reported

independently by research groups of Brookhart

[11,12] and Gibson [13-15] in 1998.

One of the main attractions of NMR is the

possibility to use NMR spectra for obtaining

information on electronic structure. The most

important interactions that provide access to

this information are the chemical shift and

nuclei with spin I ≥ 1/2.

* Corresponding author: Dr Mohamad Reza Talei Bavil Olyai, Email: [email protected], Phone No.: +982614182305 Fax: +982614418156

H. Nasiri et al., J. Appl. Chem. Res., 19, 4, 7-12 (2011)8

In this paper, computational procedure was

used has been carried out to justify 1H NMR

parameters of the iminopyridine complex

crystal structures at B3LYP using 3-21G*

standard basic set by the Gaussian 98 suite

of programs [17]. The theoretical data have

been compared with experimental 1H NMR

measurements.

Computational details

Hamiltonian Chemical shielding, acting on a

spin, I, is given by following eguation [18]:

H = IB0σγ

γ, B0 and I, are magnetogyric ratio, applied

magnetic field and nuclear spin operator,

respectively.

The term, σ is a second rank tensor called NMR

chemical shielding tensor whose elements

describe the size of chemical shielding as a

function of molecular orientation with respect

to the external magnetic field. This tensor is

converted to a diagonal matrix with σ11, σ22 and

σ33 components where σ33 > σ22 > σ11.

The isotropic chemical shielding σiso

parameters which can be related to the principal

components by following equation:

DFT calculations were performed using

Gaussian 98 program. Among various modern

functional for DFT method, we used Becke

three parameter hybrid functional combined

with Lee–Yang–Parr correlation functional

designated B3LYP [19]. The hydrogen atoms

optimizations and the chemical shielding

tensors calculations were carried out with

3-21G* standard basic sets. This basic set was

chosen since it had been successfully used in the

study of NMR chemical shielding tensors [20,

21]. It was shown that the 3-21G* basic set is

the minimum ab initio level of the calculations

that gives agreement with those obtained from

more elaborate basic sets.1H- nuclear magnetic shielding constants of

compounds were calculated by employing

the direct implementation of the Gauge-

Including-Atomic-Orbital (GIAO) method at

the B3LYP/3-21G* level of the theory [22, 23],

using corresponding TMS shielding calculated

at the same theoretical level.

Results and discussion

To study the structure of polymeric complex, we

investigated step by step iminopyridine ligand

(L) (1), L bonded to Ag+ (2), L and adjacent

nitrate bonded to Ag+ (3), L and far nitrate

bonded to Ag+ (4), L and two nitrates bonded

to Ag+ (5) complexes respectively (Figure 1).

The crystal structure of 1, 2, 3, 4 and 5 was

taken from X-ray diffraction study [24]. Since

the hydrogen atoms positions measured by

X-ray diffraction are generally not accurate,

partial geometry optimization were performed

at B3LYP/3-21G* level of theory.

Then quantum chemical computations was

carried out to justify 1H NMR parameters

H. Nasiri et al., J. Appl. Chem. Res., 19, 4, 7-12 (2011) 9

of the structures 1-5 at the same level of theory.

Table 1 presents the experimental and computed

chemical shift for selected hydrogen atoms

1 2

3 4

Table 1. Experimental and computed chemical shifts for selected hydrogen atoms.

Structure Atoms σ11

σ22

σ33

σiso

∆σ11∆σ22

∆σ33∆σiso σexp σt

1

H(2)

20.87 23.34 27.46 23.89 0 0 0 0 8.70 9.38 2 18.65 24.26 29.42 24.11 -2.22 0.92 1.96 0.22 9.16

18.12 23.08 29.23 23.48 -2.75 -0.26 1.77 -0.41 9.7934 18.5 23.85 29.37 23.91 -2.37 0.51 1.91 0.02 9.365 17.95 22.81 29.32 23.36 -2.92 -0.53 1.86 -0.53 8.95 9.911

H(11)

21.43 24.11 27.59 24.38 0 0 0 0 8.44 8.892 20.16 24.57 28.43 24.39 -1.27 0.46 0.83 0.01 8.883 20.65 24.7 28.41 24.58 -0.79 0.58 0.81 0.2 8.694 20.5 24.78 28.52 24.6 -0.93 0.67 0.93 0.22 8.675 21.07 24.81 28.53 24.8 -0.36 0.7 0.93 0.42 9.07 8.47

The isotropic chemical shielding σiso parameters are average of parameters, σ11

, σ22

, σ33

. Parameter, σt is obtained related to corresponding TMS shielding calculated at the B3LYP/3-21G* level of theory. σt and σexp parameters are in ppm.


5 Figure 1. Structure of (1) iminopyridine ligand (L), (2) L bonded to Ag+ cation (3) L and adjacent nitrate bonded to Ag+ cation (4) L and far nitrate bonded to Ag+ cation (5) L and two Nitrates bonded to Ag+ cation.

The calculated chemical shifts of hydrogen

number 2, as 9.38 and 9.91 for iminopyridine

ligand and its related complex are in good

agreement with experimental data, 8.70 and

8.44.

The hydrogen atom of azomethine group

imparts important role at NMR spectrum.

The displacement of chemical shift at

iminopyridine complex in competition with

ligand shows the coordination of ligand to

metal at complex. Comparison of calculated

chemical shifts of H number 11 at ligand

and iminopyridine complex as 8.89 and 8.47

respectively also shows good agreement with

experimental data 8.44 and 9.07.

Listed in Table 1 are the calculated 1H

chemical shielding tensors for structures

1-5. The shielding component differences

of ligand to complex, σ11, σ22, σ33, σiso, ∆σ11,

∆σ22, ∆σ33 and ∆σiso are also listed in Table1.

The results illustrate that such bonding Ag+,

NO3– influence the chemical shielding tensors

of iminopyridine in different manners. As

shown in Table 1, changes in shielding tensors

components due to bonding to iminopyridine

ligand are according to σ33, σ22 and σ11.

In general, as structure 1 to 2 reveals, the

bonding Ag+ to ligand, σ22 and σ33 of H (2) and

H (11) is deshielded due to positive charge and

electron withdrawing of additional ion, but the

changes in σ22 is minor, while components σ11

is shielded. So the changes in σ33 shielding

components are reasonable. As was to

expected, from 2 to 3-5, the chemical shielding,

σ33 of H (2) decreased due to negative charge

of nitrate group but at H (11) the changes of

chemical shifts are not noticeable.

Conclusion

1. The present study provides an explanation

H. Nasiri et al., J. Appl. Chem. Res., 19, 4, 7-12 (2011) 11

on the electronic effect in iminopyridine

ligand in comparison related complex.

2. The 1H chemical shielding tensors

components are useful tool to compare the

effect of coordination of ligand and nitrate

ions to metal an polymeric complexes.

3. Calculation of the chemical shifts by using

quantum mechanics reproduces the main

experimental tendencies of observed data.

Acknowledgment

We would like to thank Islamic Azad

University, Karaj Branch and South Tehran

Branch.

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Synthesis of Anthraquinone Containing Acrylates and Their Applications as UV-Absorber and UV-Curable Monomers

S. Baradaran Razaz1, N. Zabarjad-Shiraz*2, A. Afsharnia1, A. Ahmadi1

A. Mahmoudi1, M. Bayat3

1Department of Chemistry, Islamic Azad University, Karaj Branch, Karaj, Iran 2Department of Chemistry, Islamic Azad University, Central Tehran Branch, Tehran, Iran

3Department of Chemistry, Imam Khomeini University, Qazvin, Iran(Received 17 May 2011; Final version received 12 Auguest 2011)

AbstractAcrylates containing oxanilides were synthesized and their structures were elucidated by IR, UV, 1H-NMR and 13C-NMR. Oxanilides exhibited UV-absorbing characters as well as acting as vinylic monomers. UV-curable acrylic monomers initiated chain polymerization in the presence of UV radiation. Regaeding UV-absorbing, these compounds improved the light fastness of paints so that color chang, ∆E<1 was achieved for water-based red acrylic paint in the presence of oxanilides. High gloss alkyd paint showed excellent retention of gloss and light fastness of red pigment.Keywords: Oxanilides, UV-Absorber, Acrylic monomer.

Introduction

UV-Stabilizers (UVAs); colorless or nearly

colorless compounds exhibiting high

absorption coefficients (ε>10000), are one

of the most important classes of additives

employed to improve both physical and

mechanical properties of coatings. They

protect coatings against light-induced

damages through absorbing the harmful solar

rays preferentially by binder [1].

Photoinitiators are mostly used for coating

applications. Some common photoinitiators

are 2, 2-dimethoxy-2-phenylacetophenone,

2-hydroxy-2-methylphenylpropane-1-one,

2-hydroxy-2-methyl-1-phenyl-propan-1-one.

In this respect common problem is yellowing

during curing stage. 2-aminoacetophenones

and thioxanthone derivatives impart

yellowness. Such derivatives are used in

thin layers. Although suitable initiators for

transparent systems have become available

only in the last few years, photoinitiators

for pigmented systems have been developed

for some time. Problems concerning the

absorption of ultraviolet light, reguired for

curing, arise when the coating is pigmented * [email protected]

S. Baradaran Razaz et al., J. Appl. Chem. Res., 19, 4, 13-17 (2011)14

or when it is UV- stabilized for outdoor

applications. Ultraviolet stabilizers consist of

ultraviolet absorbers or hindered amine light

stabilizers. The curing performance depends on

the pigment absorption and particle size [2, 3].

Two representeatived mechanisms exist

for UVAs. The phenolic UVAs such as

2-hydroxybenzophenones act by establishing

rapid enol-keto equilibrium in the presence of

UV radiation [4]. However, much information

is not available on the photo physical

mechanism of non-phenolic UVAs such as

oxanilides. IR and Raman spectra indicated

the tans-planer geometry and presence of

intramolecular H-tunneling or proton transfer

process between carbonyl and imines group

(Scheme 1). This implied a planer structure

and a small solvent sensitivity of the UV

spectra [5].

N

H

R

O

N

O

R

H

N

H

R

O

N

O

R

HUV

Scheme 1. Proton transfer mechanism of UV-absorber

Free radical UV chemistries are the most

commonly encountered and represent over

80% of the UV material on the market. Often

the acrylate functional group, is used to impart

chemical unsaturation (C=C bonds) as the site

for the chemical attack [6, 7]. In this study, we

synthesized. oxanilide derivatives having UV-

absorbing properties that were polymerizable

in the presence of radical initiators (scheme 2).

ClO

OCl

TolueneO

OH

2 OO

OrthoPara

DCC

b

R1

R2

O

O

NH2

R1

NH2

3

R1

R2

NH2

R2

bOH

OHH

H

1 5

(4)

NH

O HN

O

O

O

O

O

aa

EtOAc

R1 R2

bH

Ha

Scheme 2. Synthesis of acrylated oxanilides

S. Baradaran Razaz et al., J. Appl. Chem. Res., 19, 4, 13-17 (2011) 15

Experimental

Melting points were measured with an

Electrothermal 9100 apparatus. UV spectra

were measured using VARIAN CARY 100

in CHCl3 solution (2.5×10-5 mol/lit). IR

spectra were measured by a Shimadzu IR

460 spectrometer. 1H and 13C NMR spectra

were measured with BRUKER DRX-500

AVANCE spectrometer at 300.13 and 75.5

MHz, respectively. The gloss of samples was

recorded by Sheen glossmeter at 60○ and the

shade (a, b, l, E) of samples were measured

by minolta CR-10 spectrophotometer. Oxalyl

chloride, Acrilic acid, DCC, Amino phenol

derivatives were purchased from Merk and

were used without further purification.

General procedure for the synthesis of oxanilides

(3a-b).

To a magnetically stirred mixture of 4

mmol (0.23g), acrylic acid (2) and 4 mmol

aminophenol (1a, b) in 50 mL ethylacetate,

was added 4 mmol (0.87g) DCC. After 2 hours

stirring at r.t, precipitate product filtered. The

solvent of filtrate evaporated and product

obtained powder.

4-Aminophenyl acrylate (3a). White powder.

IR (KBr, cm-1): 3280 and 3264 (NH2), 1711

(OC=O). 1H NMR (300.1 MHz, CDCl3) δ

(ppm): 6.8-7.1 (4H, m, Ar), 6.48 (1H, dd, 2J=16.7 Hz, 3J=9.8 Hz, CH=), 6.36 (1H, dd, 2J=2.1 Hz, 3J=16.7 Hz, CH=), 5.74 (1H, dd, 2J=2.1 Hz, 3J=9.8 Hz, CH=). 13C NMR (75.5

MHz, Aceton) δ (ppm): 121.5 and 127.1 (Ar),

128.0 (CH vinyl), 131.2 (CH2), 133.2 (C-O),

154.3 (C-N), 163.5 (C=O).

2-Aminophenyl acrylate (3b). Brown powder.

IR (KBr, cm-1): 3264 and 3218 (NH2), 1710

(OC=O). 1H NMR (300.1 MHz, CDCl3) δ

(ppm): 6.8-7.1 (4H, m, Ar), 6.51 (1H, dd, 2J=16.5 Hz, 3J=9.7 Hz, CH=), 6.33 (1H, dd, 2J=2.1 Hz, 3J=16.5 Hz, CH=), 5.74 (1H, dd, 2J=2.1 Hz, 3J=9.8 Hz, CH=). 13C NMR (75.5

MHz, Aceton) δ (ppm): 118.0, 121.8, 126.8

and 130.2 (4 C, Ar), 128.2 (CH vinyl), 131.

5 (CH2), 132.9 (C-O), 153.9 (C-N), 163.3

(C=O).

General procedure for the synthesis of oxanilides

(5a, b).

A solution of 0.02 mol aminophenyl acrylate

(3a, b) and 0.01 mol (1.27 g) oxalylchloride (4)

in 25 mL of toluene was stirred magnetically

for a day at r.t. Thereafter the precipitate was

filtered and washed with HCl (10%) and

crystallized in ethanol. Oxanilides (5a, b)

were obtained as yellow powder.

N1,N2-Bis (4-aminophenyl) oxalamide (5a).

IR (KBr, cm-1): 3312 (NH), 1712 (OC=O). 1H NMR (300.1 MHz, CDCl3) δ (ppm): 8.43

(1H, s, NH), 6.8-7.8 (4H, m, Ar), 5.7-6.6 (3H,

m, CH=CH2). 13C NMR (75.5 MHz, Aceton)

δ (ppm): 121.3, and 127.4 (Ar), 128.2 (CH

vinyl), 131.3 (CH2), 133.1 (C-O), 154.3 (C-

N), 158.3 (NC=O), 163.5 (OC=O).

S. Baradaran Razaz et al., J. Appl. Chem. Res., 19, 4, 13-17 (2011)16

N1,N2-Bis (2-aminophenyl) oxalamide (5b).

IR (KBr, cm-1): 3270 (NH), 1710 (OC=O),

1687 (NC=O), 1537 (C=C). 1H NMR (300.1

MHz, CDCl3) δ (ppm): 8.31 (1 H, s, NH), 6.5-

7.4 (4H, m, Ar), 5.7-5.8 (3H, m, CH=CH2). 13C NMR (75.5 MHz, CDCl3): 118.4, 121.6,

126.5 and 130.5 (4 C, Ar), 128.0 (CH vinyl),

131. 7 (CH2), 133.2 (C-O), 153.7 (C-N), 157.2

(NC=O), 163.4 (C=O).

General procedure for the polymerization of

acrylic monomers (5a, b).

To a magnetically stirred solution of 0.75g

polyvinyl alcohol (PVA) in 25 mL of H2O,

was added 0.1g (mmol) (NH4)2S2O8, 0.1g

CH3CO2Na and 12 ml butylacrylate. The

temperature raised to 80○. After 2 hrs viscose

milky latex obtained.

Procedure for fastness study of paints in the

presence of oxanilides (5a, 5b).

0.1 gram of each oxanilide was added to 100 g

red matt acrylic paints and high gloss alkyd paint

(60% solid and 24% pigment). For each prepared

sample, 100μ film of paint was applied on glass.

After 4 hrs the applied films dried completely.

Half of each film was covered to prevent UV/Vis

diffusion, and the other half was exposed to UV-

radiation (80 watt) for a week. The color change

(Δa, Δb, Δl, ΔE) of samples were measured, as

well the gloss of alkyd paint measured before

and after exposure to UV-radiation. Results were

summarized in Table (2, 3).

Result and discussion

In an alternative procedure to produce 5, the

reaction of (1a, b) with 2 was carried out in

the presence of DCC, to produce acrylated

phenols (3a, b). The process followed by the

reaction of 3 with oxalyl chloride 4 to abtain

the 5a, b.

Structures of synthesized compounds were

studied by IR, UV, 1H NMR and 13C NMR

spectra. IR of oxanilides 5 showed a N-H

peak at about 3300 cm-1 and IR of 3a-b and

5a-b showed a strong peak of C=O at 1710

cm-1. In 1H NMR spectra, the resonance of

vinilic protons appeared in 5-7 ppm region as

three doublet of doublets. The resonance of

(OC=O) and (NC=O) of 5 appeared at about

160 and 150 ppm respectively. According to

DEPT analysis, the resonance of CH and CH2

of vinyl group appeared at 128.3 and 132.9

ppm respectively. UV spectra of oxalamides

were recorded as 2*10-5 molar solutions

in chloroform and ε of compounds were

calculated by beer-Lambert equation (A=

εbc). λmax and ε were summarized in Table 1.

Generally, λmax for most of the oxalamides are

less than 300 nm and are mainly employed in

UV-B (up to 310 nm) protection. Regarding

to molar extinction coefficient (ε) as another

important factor in effectiveness of UVAs, all

oxanilides were qualified due to their ε>10000.

S. Baradaran Razaz et al., J. Appl. Chem. Res., 19, 4, 13-17 (2011) 17

Table 1. UV spectral data for oxanilide monomers (5a, b) in UV-B, UV-A and Vis (10-5 M in CHCl3)regions

CompoundUV-B (200-310) UV-A (310-400) Vis (400-700)

λmax (nm) e λmax (nm) e λmax (nm) e5a 210 341900 310 30700 400 20005b 207 326200 310 25000 400 3500

Table 2. UV Stability of red acrylic paint in the presence of oxanilides (5a, 5b)

Additive Δb Δa ΔL ΔE)dark(Sample 0.2 0.1 0.3 0.37

Sample (UV) 2.4 3.4 4.1 5.845a (UV) 0.4 0.2 0.2 0.495b (UV) 0.5 0.4 0.4 0.75

Table 3. UV stability of red high gloss alkyd paint in the presence of oxanilides (5a, 5b)

ColorGloss

ΔbΔaΔLΔEΔGlossUV Exposure

UV Absence

0.610.720.861.271.781.383Sample 1*

+0.80-1.951.802.657.07582Sample 20.530.160.040.532.179.9825a0.240.160.140.341.181.9835b

* Exposure to daylight (not UV)

Conclusion

The synthesized compounds showed UV-

absorbing properties. In addition these

compounds were able to polymerize in the

presence of radical initiators. Oxanilides with

conjugated and tautomeric structures can be

used as UVAs in alkyd and acrylic coating.

However the efficiency of these compounds

owght to tested in other coatings like polyester,

polyurethane and epoxy paints.

References:

[1] P.J. Schirman, M. Dexter, Handbook of

coating additives, Decker Marcel, New York

(1987).

[2] A. Valet, Light stabilizers for paints,

Hanover, C.R. Vincentz Verlag (1997).

[3] John. C.Crawford, Prog. Polym. Sci. 24,

7 (1999).

[4] R. Gorkman, E. Coord Bouwman, Chem.

Rev. 249, 1709 (2005).

[5] J. Pospišil, S. Nešpurk, Prog. Polym. Sci.

25, 1261 (2000).

[6] UV printing and coating facts worth

knowing, UV chemistries (2004).

[7] Y.H. Lin, K.H. Liao, N.K. Chou, S.S.

Wangc, S.H. Chu, K.H. Hsieh, European.

Polymer. Journal. 44, 2927 (2008).




Synthesis, Spectroscopy Property and Luminescence Study of the Chelate Complexes of Europium with ß-diketone and

its Derivatives

M.H. Eshraghi*, S.M. Khodaian, S. Ghadimi, S.M. Moosavi, B. Maddah Faculty of Chemistry, Department of Science, Emam Hossein University, Tehran, Iran.

(Received 25 May 2011; Final version received 20 Auguest 2011)AbstractThe disclosed red luminous invisible ink composition is comprised of europium complex which is represented by the formula (1).

1. CF3(CF2)C(O)CH2C(O)C(CH3)2. CH3C(O)CH2C(O) CH3

3. (CF3)C(O)CH2C(O) CH3CF3C(O)NHP (O)R1R2(R1&R2=C6H5CH2NCH3)In this work, we made invisible offset print inks based on europium (III) ß–diketonates complexes and their derivatives. Moreover, we used a new formulation by oprating such as solvent, resins, semi dry oils, anti-adhesive material, wet silicate aluminums, powder magnesium silicate for the synthesis of these inks.Keywords:Spectrophotometry, Stavudine (STV), 2, 6-Dichloroquinone chlorimide (DCQC), CeIV.

Introduction

Complex of ß-diketons of lanthanide element is

the common coordination compounds of these

elements that has been investigated [8,9]. Two

*[email protected]

reasons which make these compounds special

is that different ß - Diketone compounds are

not only commercially exist but also they

are relatively easy to synthesis. Due to the

M.H. Eshraghi et al., J. Appl. Chem. Res., 19, 4, 18-26 (2011) 19

widespread application of these compounds,

particular research have been conducted in

this area [10]. The first complex ß-Diketone

lanthanide element was synthesized in the

late 19th century at Eurabion Center [11].

Since then, because of their importance, a

large number of these complexes has been

synthesis and to some of them were added

materials such as polymers, zeolite [12,13] or

liquid crystals [14-19] and glasses to prepare

the photoluminescence, electroluminescence,

tribololuminescence and chemiluminescence

compounds [20-25]. In recent years, these

compounds have been used in making

instruments such as laser devices, the light

emission organic diode (LED) and liquid

crystal display (LCD). In addition, because

of their unique properties, these complexes

have been used in various sciences such as

chemistry research which involve the analysis

of lanthanide ions, the chemical sensors and

in the forensic sciences as the emergence

of hidden fingerprints. One of the main

applications of the ß -Diketon lanthanides

complexes, is use their in invisible ink because

of their fluorescence property. In as much as

the human eye exhibits lower sensitivity in the

red region of the electromagnetic spectrum, it

is essential to minimize the loss of emission

efficiency due to peak broadening, which

results from vibration or transfer phenomena.

In this work we tried to synthesis the trivalent

complex of EU+3 (the most important elements

of lanthanides with the red light emission)

with ß-diketones and the nitro sulfonate-

derivatives to study their differences in terms

of emission intensity and efficiency. In recent

years, is has been proven that the incorporation

of organic groups generates higher stability of

lanthanide and optimizes the vapor pressure

This insertion also increases the applicability

of this complex.

Experimental

Materials

Analytical grade Europium nitrate was

purchased from ERDEL Company,

trifloronaftil 1,3 butadiene from ACROSS

company, 2-tionyl 3,3,3 triflouroaceton from

MERC and other chemicals were of analytical

grade.

Instruments

Spectroscopic experiments were performed

using emission spectrophotometer LS50B

(Perkin Elmer), FT-IR spectrometer IFS-88

(BRUKER) and UV-Vis spectrophotometer

LAMBDA2 (BRUKER).

Synthesis of 1-(2-tionel )-4-3,3,3-trifluoro

acetone –europium complexes (TTFA-Eu) [18]

Europium nitrate 5 hydrated 0.01M (from

Riedel companies) was prepared by adding

4.28 g of this compound in 100 ml water.

0.03 M solution of 1 - (2 - Tionyl) 4-3,3,3

triflouroaceton (from Merck) was prepared

M.H. Eshraghi et al., J. Appl. Chem. Res., 19, 4, 18-26 (2011)20

in 150 ml water. Moreover, by gradually

adding ammonia solution to mixture, the pH

was adjusted in the range of 8- 9. At ambient

temperature, mixing the was continued

for 30 minutes to complete reaction. After

separating the water layer, the ether layer

was washed with water and the barium sulfate

was dehydrated and then the ether layer was

dried with sodium sulfate. The ether layer was

filtered and evaporated. 5.6 g of the complexes

was obtained.

Synthesis of TTFA

The first solution was made by dissolving

2.2g TTFA (0.01M) from Merck in 3.5 ml

acetic an by dride in a baker. The second

solution was prepared by adding 1.2 grams

of nitric acid (70%) in 6 ml antydride acetic.

Half of the second solution was placed into

the Erlenmeyer flask inside the cold water

bath while the stirring with magnet stirrer.

Then, of the first solution was added into the

Erlenmeyer flask dropwise and cautiously, to

prevent the rise in the temperature of solution.

Then the rest of second solution was added

followed by adding the rest of the first solution

drop wise. The color of solution should be

brown. Otherwise, if the color changes to

dark red or pink, it means the compound has

been oxidized and decomposed. After, the

reduction of the initial reaction temperature,

the temperature was increased to 40ºC in a

water bath to complete the nitration reaction.

In these processes stirring the solution has been

continued for 6 hours. Brown color solution

was poured ice chips and was cautiously and

continuously while rapidly stirred allowed

that the yellow crystals remain for a day in

the solution and then the solution has been

filtered.

FT-IR: 1304 cm-1, 1509 cm-1

UV/VIS λmax=345 nm, 275 nm

Emission λex=390


Synthesis of (NO2 –TTFA)3 EU (NO3 ) complex

0.03M of 4, 4, 4 triflouro1, 2 - naphtyl)–

1,3-butadiene from Across Company and

0.02 M tri- phenylalanine phosphine was

added to 100 ethanol to neutralize the pH of

solution. A solution was made by solving

0.01M Europium (III) Nitrate 5 hydrate in

10ml water. This solution was added drop by

drop to the previous solution while stirring to

keep the temperature constant at 40ºC. The

solution was filtered and the yellow crystals

were washed with water. The weight of the

complex was about 8g.

FT-IR: 1302 cm-1, 1349 cm-1, 1935 cm-1, 1510 cm-1

UV/VIS λmax=345 nm, 266nm

Emission λex=390

Synthesis of (EU –TPO –NTFA) complex [26]

0.03M of 4,4,4 triflouro(1,2 -naphtyl) –

1,3-butadiene (99% purity from Across

Company) and 0.02 M tri- phenylalanine

phosphine oxide was added to 100 ethanol

to neutralize the pH of the solution. Another

solution was made by solving 0.01M Europium

(III) Nitrate 5 hydrate in 10ml water. This

solution was added gradually to the previous

solution while stirring to keep the temperature

constant at 40ºC. The solution was filtered and

the yellow crystals were washed with water.

The weight of the complex was about 8g.

FT-IR: 1304 cm-1, 1412 cm-1, 1509 cm-1

UV/VIS λmax=330 nm, 263 nm, 210 nm

Emission λex=390


Synthesis of NTFA-SO3 complexes [27]

4,4,4 triflouro (1,2 -naphtyl) – 1,3-butadiene

0.01 M (99% from Across Company), 0.03 ml

concentrated sulfuric acid (2 ml) was added in a

balloon stirring magnet. Reaction temperature

was raised to about 70 to 80ºC using a hot

water bath and stirring was continued for 4

hours. The color of solution will change to dark

red. Then solution was cooled to the ambient

temperature. Then the solution was added to

ice crystals with vigoriousstirring. Finally,

yellow crystals was filtered and then washed

with water till neutral water was rinsed.

FT-IR: 1375 cm-1, 1450 cm-1 3373 cm-1

Emission λex=390

Synthesis of (EU-TPO-SO3 –NTFA) complexes [28]

A mixture of 0.03 Mol NTFA-So3 (which

was synthesized in five steps) and 0.02M

phenylalanine phosphine oxide was added in 5

mL ethanol. This solution was heated until the

contents are completely dissoved. By adding

about 3ml of 0.1N NaOH the solution was

neutralized. Another solution was prepared by

dissolving 0.01M Europium (III) nitrate salt

5 hydrated in 2 ml of water, which was added

to the first solution gradually adding untill a

yellow or light orange crystals obtained. Then

the crystals was filtered by filter paper and then

washed by water and then allowed to dry in air.

FT-IR: 1537 cm-1, 1518 cm-1, 3700 cm-1

UV/VIS λmax=342 nm, 267nm, 207nm

Emission λex=390


Result and Disscution

The emission spectrum of prepared complexes

was taken in the range of 300-900 nm-1 at 500

ppm concentration in methanol solvent which

(Figures1 and 2). The increase in emission

intensity of complex with nitro substitute is

Figures 1. Emission spectrum of prepared complexes in methanol solvent, A=NTFA-TPO-Eu, B=NTFA-SO3

Figures 2. Emission spectrum of prepared complexes in methanol solvent, A=(TTFA-Eu), B=(TTFA-NO2)3-Eu(NO3)2

present in Figures1 with nitro substitute, but in

Figures2 the decrease in emission intensity for

sulfur substitute is observed. The mechanism for

energy transfer from organic ligand to lanthanide

ions which has mainly been accepted was

introduced by Whan and Crospy [29] (Figures3).


Figures 3. Mechanism for energy transfer from organic ligand to lanthanide ions.

While ultraviolet light was radiated to complex,

the ligand lanthanide complex excited to the

first excited vibration level of Singlet level.

(S1-S0). Molecules undergo rapid internal

transmission to lower vibration levels of the

S1 mode. For instance, through the interactions

with solvent molecules, the excited single level

can return to initial level state through radiation

(fluorescence S0-S1). In addition, intra-system,

non-radiative transition of single mode S1 to T1

triplet state is possible. Then triplet state T1 can

return to base state through radiation phenomena

and this action will be by spin forbidden

transition (T1- S1) which happens in molecular

fluorescence. Frequently, the complex may

develop a non-radiative transfer from triplet

state to single state of lanthanide ions. After

indirect excitation by the energy transfer,

the lanthanide ion may undergo a radiative

transfer to 4F lower state. These phenomena

will be occurred through pseudo- non-linear

specific photoluminescence or inactivation

through non-radiation process. According to

the work of Crosby-Whan, the main reason for

being neutral in lanthanide ion is the coupling

by non-vibrating irradiation with ligand and

solvent molecules. However, the mechanism

of energy transition from excited triplet

states of lanthanide ion has been introduced

by Kleimnerman [30], but it was specified

that those mechanism was not important and

luminescence by lanthanide ion was possible

any by some certain states which. are called

resonance states. The main resonance states of

Sm3+, Eu3+, Tb3+, Dy3+ are 4G5/2,5D0,

5D4, 4F9/2

respectively.

If the lanthanide ion excited to a non-

radioactive state through non-radioactive

process, it will be motivated to reach a

resonance level. Then, the radiative transitions

will compete with non-radiative processes and

as a result the emission of central metal will


appear. The linear emission for lanthanide

ions was possible just on condition that the

neutralization and the molecular fluorescence

being at mianimum level of energy. In order

to fill a resonance state of lanthanide ion it is

necessary that the lowest energy triplet state

in complex located in equal or higher energy

level of resonance states. If the energy state

of organic ligand is in lower level than the

lanthanide ion, the molecular fluorescence or

phosphorescence of ligand will be occurred.

But in some cases, the emission light is

possible too. It means that the luminescence of

a specific lanthanide ion is a sensitive function

of lower level energy of triplet state of complex

rather than a resonance state of lanthanide ion.

Because the triplet state depends on the ligand

ion, thus the observed luminescence intensity

of specific lanthanide ion can be controlled by

changing the ligand [31]. Different parameters

which control triplet level position such

as temperature are also important. At the

designed ligands, nitro group substitute causes

reduction in the energy gap between excited

energy levels of ligand (Tionyl) with the metal

centre. Electron transfer will occur from the

lowest triplet level equal or higher level of

ligand than resonance state of Europium, so

the emission of central metal will be appear.

The emission of light will decrease while the

energy gap between the excited states of organic

ligand with resonance state of lanthanide ions

being too much (emission spectra 1). These

phenomena will be observed in complexes with

sulfur substitution and therefore the emission of

(NTFA-So3h)-Tpo-Eu complex is smaller than

non substitute complexes (Emission spectra2).

Also, the luminescence observed for specific

lanthanide complexes is sensitive to lower

energy level of triplet state of complex than the

resonance state of lanthanide. It means that if this

excited state of organic ligand is in lower level

of resonance state of lanthanide ion, no emission

will occur. Since the position of triplet state of

complex depends on the type of ligand, it is

possible to control or optimize the luminescence

emission of intensity of certain lanthanide ion

by changing the ligand substitution. Therefore

the increase in luminescence intensity due to

higher energy transfer from lanthanide ions

to ligand are detectable and depend on the

increase in entropy around the lanthanide ion.

These complexes have multiple uses in various

industries including invisible ink in security

manufacturing.

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Selective and Validated Spectrophotometric Methods for Determination of Acyclovir and Ganciclovir with 2, 4 DNP

as Reagent

T.Anil Kumar, B. M. Gurupadayya*, M.B. Rahul Reddy, M.V. Prudhvi RajuDepartment of pharmaceutical analysis, JSS college of pharmacy, JSS University, India

(Received 27 May 2011; Final version received 22 Auguest 2011)

AbstractTwo simple, sensitive, selective, accurate, precise and economical methods (method A and B) have been developed for the quantitative estimation of ganciclovir in bulk drug and its pharmaceutical formulations. In method A, an aqueous solution of ganciclovir reacts with 1-fluoro-2, 4-dinitrobenzene (Sanger’s reagent) at borate buffer pH 9 and forms a yellow color complex and absorbance was measured at 354 nm. In method B, involves adding a measured excess of NBS to ganciclovir in acid medium followed by determination of residual NBS by reacting with a fixed amount of methyl orange and measuring the absorbance at 508 nm. The Beer’s law was obeyed in the concentration range 0.2-0.6 µg/ml and 1-5μg/ml for method A and B respectively. The accuracy and reliability of the methods were further ascertained by performing recovery tests via standard-addition method. The recoveries of ganciclovir tablets are in the range 99.24, 99.16 respectively. The proposed method is simple, rapid, precise and convenient for the assay of ganciclovir in commercial tablet preparations. Keywords: Ganciclovir (95.3%), 1-fluoro-2, 4-dinitrobenzene (Sanger’s reagent), N-Bromosuccinimide (NBS).

* Dr. BM Gurupadayya, Department of Pharmaceutical Analysis, JSS College of Pharmacy, JSS University, Shivarathreashwara Nagar, Mysore-570 015, Karnataka, India, Fax: +91-821-2548359, Mobile: +91-9242886136 E mail: [email protected]

IntroductionGanciclovir (GCV) is chemically 2-amino-1,9-[{2-hydroxyl-1-(hydroxymethyl)ethoxy} methyl]-6H-purine-6H-one. Ganciclovir is an acyclic guanosine analog that requires triphosphorylation for activation prior to inhibiting the viral DNA polymerase. It is used in treatment of cytomegalovirus (CMV) infection in AIDS patients [1]. Ganciclovir

exhibit antiviral activity against herpes simplex virus (HSV) and cytomegalovirus (CMV) at relatively low inhibitory concentrations. It is official in Martindale [2] Merck Index [3] and USP [4]. Literature survey reveals that few methods like liquid chromatography using pulsed amperometric detection in plasma [5], high performance liquid chromatography (HPLC) with pre column fluorescence deviation

T.Anil Kumar et al., J. Appl. Chem. Res., 19, 27-40 (2011)28

using phenyl glyoxal in serum [6].

Several methods which include

radioimmunoassay (RIA) [7] and enzyme-

linked immunosorbent assay [8, 9] have been

initially reported for the quantification of this

GCV in biological fluids. Some combination

method for simultaneous determination

of GCV, and acyclovir by flow-injection

chemiluminescence method [10], acyclovir

and penciclovir in human plasma using

fluorescence detection [11], teicoplanin in

plasma [12] and acyclovir and guanine [13]

were developed. Only few spectrophotometric

methods [14,15] are reported for the estimation

of ganciclovir using spectrophotometry in

bulk drug or its formulations.

Sanger’s reagent has been utilized as a

chromogen for the spectrophotometric

estimation of many compounds of

pharmaceutical interest such as desloratadine

[16], enalapril [17], lisinopril [18] and

gabapentin [19]. A great number of organic

compounds have been spectrophotometrically

determined using excess NBS as oxidant in the

presence of celestine blue for propranolol and

tetracycline hydrochlorides [20], omeprazole

[21] azathioprine and astemizole [22]. However,

the reactions of N-Bromo succinamide

with ganciclovir and Sanger’s reagent with

ganciclovir have not been investigated so far.

The present study describes the evaluation of

N-Bromo succinamide and Sanger’s reagent

used as reagents for the development of

simple and rapid spectrophotometric method

for the determination ganciclovir in its

pharmaceutical dosage forms.

Method & Materials

Instruments

A double-beam Shimadzu 1700 UV

spectrophotometer, connected to computer

and loaded with UV solution software was

used. For an intermediate precision study and

for ruggedness, a different Shimadzu 1800 UV

spectrophotometer connected to computer with

UV-PC software was used. Both instruments

have an automatic wavelength accuracy of

0.1 nm and matched quartz cells of 10 mm

(1.0 cm) cell path length. The absorbance

of ganciclovir in the selected medium at

respective wavelength was determined and the

apparent molar absorptivity was calculated.

1-Flouro-2-4-dinitro benzene (Sanger’s

reagent) 0.5 %( w/v)

0.5 g of Sanger’s reagent was accurately

weighed transferred into a 100 ml calibrated

flask, dissolved in methanol, and make up the

volume up to the mark to obtain a solution

of 0.5% (w/v). Reagent should be protected

from light during use and should be handled

carefully since it is a skin irritant. It is stored

in a refrigerator and it was stable for 4 months.

Borate buffer pH 9

Place 50ml 0.2M boric acid, 50 ml 0.2M

T.Anil Kumar et al., J. Appl. Chem. Res., 19, 27-40 (2011) 29

Method A

A 1 ml quantity of 0.5% Sanger’s reagent

and 0.2 ml of borate buffer were added to

test tube containing 3.5 ml of ganciclovir

and subjected for heating at 900 C for 10

minutes and cool the solution, made up to

the mark with distilled water. The absorption

spectrums of the complex were determined

against blank solution and the wavelengths of

maximum absorption (λmax) of the products of

the reactions were noted.

Method B

A 1 ml quantity of 0.02% NBS solution, 1.0

ml of 1M HCl were transferred into test tube

and 3.5 ml of ganciclovir stock solution were

added and kept it aside for 20 minutes. Then

add 1 ml of 0.01% methyl orange dye which

results in the formation of pink color complex.

The solutions were made up to 10ml with water.

The absorption spectrum of the complex was

determined against blank solution prepared

without drug. The wavelength of maximum

absorption (λmax) of the product was recorded.

Optimization Studies

Effect of Sanger’s reagent concentration

In the study of Sanger’s reagent, it revealed

that the reaction was dependent on Sanger’s

reagent concentration. The absorbance of the

reaction solution increased as the Sanger’s

reagent concentration increased, and the

highest absorption intensity was attained at

potassium chloride into 200ml volumetric

flask, then add 20 ml of 0.2M NaOH and finally

make up the volume with distilled water.

N-Bromosuccinimide (NBS) 0.02 %( w/v):

0.02 g of N-Bromosuccinimide was accurately

weighed transferred into a 100 ml calibrated

flask and make up the volume up to the mark

with distilled water. The solution was freshly

prepared and protected from light during the

use.

Methyl orange 0.01%

0.01 g of methyl orange is accurately weighed

and transferred into a 100.0ml volumetric flask

and dissolved it with small quantity of water,

then made up to the mark with distilled water.

Hydrochloric acid 1M

8.5 ml of concentrated HCl is accurately

measured and transferred into a 100.0 ml

volumetric flask and made up to the mark with

distilled water.

Preparation of standard solution

Accurately weighed 100 mg of ganciclovir

was dissolved in small quantity of distilled

water and the solution was further diluted

with distilled water to mark to obtain a final

concentration of 100 µg/ml.

Selection of Analytical Wavelengths for

ganciclovir


concentration of 0.5 % (w/v). Higher Sanger’s

reagent concentrations up to 1.0% had no effect

on the absorption values. Further experiments

were carried out using 0.5 % of the reagent

and results obtained were showed in figure 1.

Figure 1: Effect of Sanger’s reagent (%) on formation of colour product

Effect of NBS Concentration and hydrochloric

acid

In the study of Sanger’s reagent of NBS

reagent, revealed that the reaction was

dependent on NBS reagent concentration.

The absorbance of the reaction solution was

increased as the NBS concentration increased,

and the highest absorption intensity was

attained at NBS concentration of 0.02 %

(w/v). Higher NBS concentrations up to 0.05

% had no effect on the absorption values

Further experiments were carried out using

0.02 % and results obtained were showed in

figure 2. It is also observed that 1 ml of 1M

hydrochloric acid is necessary for absorbance

and further more addition has no effect on the

absorption (figure 2).

Figure 2: Effect of NBS and HCl on formation of color product


Procedure for calibration curve

Method A

Aliquates of 0.2 ml, 0.4 ml, --- 0.6 ml of 10 µg/

ml ganciclovir were transferred into different

10 ml volumetric flasks, to these solutions 1.0

ml of Sanger’s reagent and 0.2 ml of borate

buffer pH 9 were added. The mixture was

then gently shaken and subjected for heating

at 90o C for 10 minutes and then solution was

cooled. The contents were diluted up to 10ml

with distilled water. The absorbance of each

solution was measured at 353 nm against the

reagent blank prepared in the same manner,

without the analyte. The absorption spectra

and calibration curve are represented in the

figure 3 and 4 respectively.

Figure 3: Absorption spectra of ganciclovir with Sanger’s reagent and NBS reagent

00.10.20.30.40.50.60.70.80.9

0 0.2 0.4 0.6 0.8Concentration (µg/ml)

Abs

orba

nce

Figure 4: Linear graph of ganciclovir with Sanger’s reagent

Method B

Aliquates of 2 ml, 3 ml, --- 5 ml of 100 µg/ml

ganciclovir were transferred into different 10

ml volumetric flasks, to these solutions 1.0 ml

of 0.02% NBS, 1.0 ml of 1M HCl and kept

it aside for 20 minutes and then add 1 ml of

methyl orange indicator. The mixture was then

gently shaken until the appearance of color


chromogen. The contents were diluted up to

10 ml with distilled water. The absorbance of

each solution was measured at 508 nm against

the reagent blank prepared in the same manner,

without the analyte and the absorption spectra

and calibration curve of ganciclovir is shown

in figure 3 and 5 respectively.

Figure 5: Linear graph of ganciclovir with Sanger’s reagent

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5 6Concentration (µg/ml)

Abs

orba

nce

Analysis of commercial pharmaceutical

preparations

Twenty capsules of ganciclovir (Natclovir

and Ganguard) were weighed accurately and

ground into a fine powder. An amount of the

powder equivalent to 100 mg of ganciclovir

was weighed into a 100 ml volumetric flask, 60

ml of water added and shaken thoroughly for

about 20 min. Then, the volume was made up

to the mark with water, mixed well and filtered

through Whatmann filter paper No. 41. First

10 ml portion of the filtrate was rejected and

2.5 ml of the tablet extract was subjected to

analysis using the procedure described above.

Quantification

The limits of the Beer’ law, molar absorptivity

and Sandell’s sensitivity values were evaluated

and are given in Table 1. Regression analyses

of the Beer law plots at their respective λmax

values revealed a good correlation. Graphs of

absorbance versus concentration showed zero

intercept, and are described by the regression

equation, Y = bX + c (where Y is the absorbance

of a 1 cm layer, b is the slope, c is the intercept

and X is the concentration of the drug in μg/

ml) obtained by the least-squares method. The

results are summarized in Table 1.


Table 1: Optical characteristics of spectrophotometric method

Parameter Method A Method BColor Yellow Pink

λmax(nm) 353nm 508 nmBeer’s law range (μg.ml-1) 0.2-0.6 1-5

Molar absorptivity(L.mol-1.cm-1) 0.1×103 0.32×103

Sandell’s Sensitivity (µg.cm-2) 0.00068966 0.00624Limit of detection (µg.ml-1) 0.05 0.1045

Limit of quantification (µg.ml-1) 0.1619 0.446Correlation coefficient, R 0.9998 0.9997

Slope b 1.4204 0.789Intercept a 0.0051 0.0262

Standard deviation of slope 0.03884 0.004203Standard deviation of intercept 0.002715 0.0007805

Percentage recovery 99.24 99.16

Validation of the method

The validity of the method for the assay of

ganciclovir was examined by determining the

precision and accuracy. This was determined

by analyzing six replicates of the drug within

the Beer’s law limits. The low values of the

relative standard deviation (R.S.D.) indicate

good precision of the methods. To study the

accuracy of the methods, recovery studies

were carried out by the standard calibration

curve method. For this, known quantities of

pure ganciclovir were mixed with definite

amounts of pre-analyzed formulations and the

mixtures were analyzed as before. The total

amount of the drug was then determined and

the amount of the added drug was calculated

by difference. The average present recoveries

obtained were quantitative indicating good

accuracy of the methods.

Specificity and selectivity

Ganciclovir solutions were prepared in the

selected media with and without common

exicipients separately. All solutions were

scanned from 800 to 200 nm at a speed of

200 nm min−1 and checked for change in

the absorbance at respective wavelengths.

In a separate study, drug concentration of

0.2 μg/ml for method A and 2 μg/ml for

method B was prepared independently from

pure drug stock solution in selected media

and analyzed paired t test at 95 % level of

significance was performed to compare the

means of absorbance

Linearity

To establish linearity of the proposed

methods, a separate series of solutions of

ganciclovir for method A (0.1-0.6 µg/ml)

and for method B (1-5 µg/ml) were prepared

from the stock solutions and analyzed. Least

square regression analysis was performed on

the obtained data.


Precision

This good level of precision was suitable for

quality control analysis of the investigated

drug in their pharmaceutical dosage forms.

The precision of the proposed methods was

ascertained by actual determination of six

replicates of fixed concentration of the drug

within the Beer’s range and finding out the

absorbance by the proposed method in all the

three drugs. The results are given in Table 2.

Accuracy

To determine the accuracy of the proposed

method, recovery studies were carried out

by adding different known amounts of bulk

samples of ganciclovir within the linearity

range were taken and added to the pre-analyzed

formulation of concentrations 0.2 µg/ml and

2µg/ml for method A and B respectively. The

results are given in Table 3.

Table 2. Accuracy and method precision data for the developed method

Drug S.No Label Claim(mg)

Amount found*

%Purity*

Average (%) S.D R.S.Da RSDb S.E.M

Method A

1

250

248.42 99.36

99.30 0.019 0.0716 0.0710 0.013

2 247.68 99.10 3 250.04 100.02 4 249.98 99.90 5 250.68 100.27 6 248.98 99.59

Method B

1

250

250.56 100.22

99.56 0.022 0.040 0.0396 0.013

2 249.12 99.65 3 250.62 100.25 4 247.32 98.93 5 246.40 98.56 6 248.46 99.35

SD. Standard deviation; SEM. Standard error of mean; RSD. Relative standard Deviation; aintra-day precision, binter-day precision.

Table 3. Standard addition of ganciclovir for accuracy formulation

Studied Amount

taken(µg.ml-1)Amount added

Total found (µg.ml-1)

Recovery (%)

Method A 0.2 0.4 0.59 98.46 Method B 2 2 0.38 99.42

Robustness and Ruggedness

To evaluate the robustness of the methods,

reaction time and reagent concentrations were

slightly altered with reference to optimum values

in spectrophotometry. To check the ruggedness,

analysis was performed by four different analysts;

and on three different spectrophotometers by the

same analyst. The robustness and the ruggedness

were checked at three different drug levels. The

intermediate precision, expressed as percent

RSD, which is a measure of robustness and

ruggedness was within the acceptable limits as

shown in the Table. 2.

Limit of detection (LOD) and limit of

quantitation (LOQ)


The LOD and LOQ for method A and method B

by the proposed method were determined using

calibration standards. LOD and LOQ were

calculated as 3.3 σ/S and 10 σ/S, respectively,

Where Sis the slope of the calibration curve

and σ is the standard deviation of y-intercept

of regression equation.

Results and Discussion

In method A Sanger’s reagent forms a yellow

color complex with ganciclovir in alkaline

medium and their absorbances were measured

at 353nm. Therefore, the present study

was devoted to explore Sanger’s reagent as

derivatizing reagents for the determination

of ganciclovir in pure and pharmaceutical

dosage forms. The reaction mechanism of

drug Sanger’s reagent shown in the Scheme

1. The method obeys Beer’s law is obeyed

in the range of 0.2-0.6 μg/ml and standard

deviation of slope and intercept were found

to be 0.03884 and 0.002715. Optimization

of the spectrophotometric conditions was

intended to take into account the various goals

of method development. Analytical conditions

were optimized via a number of preliminary

experiments. The effect of Sanger’s reagent

concentration was studied and found that

0.5% gave good absorbance values so further

experiments were carried out using 0.5 %

Sanger’s reagent and effect of heating time on

formation of color product was studied and

different buffer solutions in the pH range of

8.0-10 were tested for reaction of Sanger’s

reagent with ganciclovir. Best results were

obtained in case of borate buffer pH 9.


Scheme 1: Mechanism of reaction of ganciclovir with Sanger’s reagent

F

NO2

NO2

Sanger's reagent

H+ F+

Yellow colored complex

Intermediate

N

HN

N

NH2N

O OH

HO

OGanciclovir

N

HN

N

NNH

O OH

HO

O

F

NO2

O2N

N

HN

N

NNH

O OH

HO

ONO2

O2N

Method B is based on the oxidation reaction

between ganciclovir and NBS in acidic

medium. The reaction mechanism of drug

Sanger’s reagent shown in the Scheme 2.

The Beer’s law is obeyed in the range of 1-5

μg/ml and standard deviation of slope and

intercept were found to be 0.004203 and

0.0007805. The method is indirect and is based


method, the absorbance increased linearly with

increasing concentration of drug. Ganciclovir

when added in increasing amounts to a fixed

amount of NBS consumes the latter and there

will be a concomitant fall in its concentration.

When a fixed amount of dye is added to

decreasing amounts of NBS, a concomitant

increase in the concentration of dye results.

This is observed as a proportional increase in

the absorbance at the respective wavelengths

of maximum absorption with increasing

concentration of ganciclovir as indicated by the

correlation coefficients of 0.9997 respectively.

on the determination of residual NBS after

having allowed the oxidation reaction to go to

completion under the specified experimental

conditions. The amount of NBS reacted

corresponds to the drug content in the method.

The ability of NBS to oxidize ganciclovir and

bleach the colors of methyl orange dye has been

used for the indirect spectrophotometric assay

of the drug. In this method, the drug is reacted

with a known excess of NBS in acid medium,

and the unreacted oxidant is determined by

reacting with a fixed amount of methyl orange

and measuring the absorbance at 508 nm. In this

Scheme 2: Mechanism of reaction of ganciclovir with NBS

N

HN

N

NH2N

OGanciclovir

4 NBS Oxidation

N

HN

N

NH2N

O

OOxidized ganciclovir

4 NBS N N

H3C

H3C

N S

O

O

O-

N N

H3C

H3C

N S

O

O

O-

BrominationBr

Br

Br

Br

Methyl Orange

Tetra Bromo Methyl Orange

O

O

O

HO

OH


Preliminary experiments were performed to

determine the maximum concentrations of

the dye spectrophotometrically, and these

were found to be 0.01%. 1M Hydrochloric

acid (1 ml) was the ideal medium for the

oxidation of ganciclovir by NBS as well as

the latter’s determination employing methyl

orange dye. The reaction between ganciclovir

and NBS was unaffected when 1.0 – 2.5 ml

of 1 M hydrochloric acid in a total volume of

about 7 ml was used. Hence, 1.0 ml of 1 M

hydrochloric acid is used for both steps in the

assay procedures. For a quantitative reaction

between ganciclovir and NBS, a contact time

of 20 min was found necessary and constant

absorbance readings were obtained when

contact times were extended upto 20 minutes.

A standing time of 5 min was necessary for

the bleaching of the dye color by the residual

NBS. The measured color was found to be

stable for several hours in the presence of the

reaction product (figure 6). Based on various

optical and validation parameters method A is

more sensitive and reliable method compared

to method B.

Figure 6: Effect of reaction time with absorbance

The results were in agreement with the labeled

amounts. For comparison, a conventional UV

spectrophotometric method developed in our

laboratory was used for parallel comparison.

The recovery percentages for 99.24 and 99.16

for method A and B respectively (Table 4). This

indicated similar accuracy and precision in the

analysis of the investigated compounds in their

pharmaceutical dosage forms.


Table 4. Results of determination of ganciclovir in formulations and statistical comparison with the reference method

Pharmaceutical dosage form

Labelled Amount

Amount found by proposed methods

(mg)

Recovery of Reference

method

Recovery of proposed methods

(%)

Method A (Natclovir) 250 mg 248.46 98.73

99.38 t=0.566 f=1.084

Method B (Ganguard) 250 mg 249.12 97.50

99.65 t=0.594 f=1.182

Conclusion

The reagents utilized in the proposed methods

are cheap, readily available and the procedures

do not involve any critical reaction conditions

or tedious sample preparation. Moreover, the

methods are free from interference by common

additives and excipients. The wide applicability

of the new procedures for routine quality

control was well established by the assay of

ganciclovir in pure form and in pharmaceutical

preparations.

Acknowledgements

The authors express their sincere thanks to

Strides Arco Lab Limited, Bangalore, India

for supplying the gift sample of ganciclovir

(purity-95.3%). Thanks to the Principal, JSS

College of Pharmacy, Mysore, for providing

the necessary facilities.

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Analytical Technique for Detection of Motor Gasoline Adulteration Using Gas Chromatography-Detailed

Hydrocarbon Analysis (DHA)

J.Balakrishnan1,V.Balasubramanian2* 1Assistant Professor of Chemistry, Professor of Chemistry and Environmental Science, AMET University

2Professor of Chemistry and Environmental Science, AMET University(Received 14 May 2011; Final version received 05 Auguest 2011)

AbstractThe adulteration of motor gasoline with superior kerosene has been studied using gas chromatography-Detailed Hydrocarbon Analysis (DHA). The gas chromatograph study showed that even a micro amount of individual hydrocarbon can be easily detected. The blended sample of motor gasoline had been analysed by GC-DHA and the data were correlated for motor gasoline adulterations. The difference in associate properties of motor gasoline gives basic idea for role of adulteration.Key words: Motor Gasoline, Gas Chromatography, DHA, Adulteration, Superior Kerosene.

* Professor of Chemistry and Environmental Science, AMET University, 135, East coast road, Kanathur, Chennai, TamilNadu-603112, [email protected]. Tel:-91-44-27472155, Fax:-+91-44-27472804

Introduction

The detailed study on Information theory in

analytical chemistry[1] (Scott RPW (2003),

Chemical test methods[2] (ZolotovYA,

Ivanov VM, Amelin (2002) of analysis

using Gas chromatography[3], Chemical

identification and its quality assurance[4]

by Milman.B.L.(2011) are available in the

literaturs. Based on the above methods a

research had been conducted on motor gasoline

sample with hydrocarbon[4]-superior kerosene

[5]. A standard gasoline samples were obtained

from Oil Company, these samples are blended

with superior kerosene. The samples of motor

gasoline are analyzed by gas chromatography

[6] flame ionization detection (GC–FID)

using a low-polarity capillary column. The

gasoline [7] samples are characterized using

detailed hydrocarbon analysis (DHA).

The quantitative [8] data of motor gasoline

obtained by the chromatographic method

are compared with the same motor gasoline

blends. The study of comparative analysis

was used to determine the degree of similarity

[9] between the gasoline sample and its

blends. GC-Detailed hydrocarbon analysis

has shown that addition of superior kerosene

in motor gasoline confirmed the characteristic

J.Balakrishnan et al., J. Appl. Chem. Res., 19, 4, 40-48 (2011)42

change in the most of the properties. The gas

chromatography [10] instrument gave only

the area percentage. This area percentage

is to be feed into using Hydrocarbon expert

Software. The software hydrocarbon expert

{HE} give various data’s like i) Carbon by

group ii) Carbon by number iii) Carbon by

Composite iv) Carbon by Component list v)

Calculated physical properties vi) Calculated

octane number –Research Octane Number &

Motor Octane Number-RON &MON. These

software data give immense information about

the adulteration.

Experimental

The Motor gasoline standards are obtained

from Indian oil Company [11]. It was blended

with known amount of superior kerosene

[12]. This motor gasoline and its blends are

introduced into gas chromatographic column

which separates the hydrocarbon [13][14] in

boiling point order. The column temperature is

raised at reproducible rate and the area under

the chromatogram [15] is recorded throughout

the run.

2.1. Method of analysis by Gas chromatography

Column Details- Petrocol DH 100 meters,

100% Dimethyl polysiloxane (Non-Polar) 0.25

mm id, Sample size-0.5 μl, Fuel gas- Hydrogen

@ 30mL/min, Oxidant- Air @ 300mL/min,

Make up gas- Helium @ 20mL/min, Injection

temperature 260°C, Injection mode- Split

Mode-200 ml / Min- Split ratio1:98 Inject

pressure-44 Psi, Detector- Flame Ionisation

Detector, 265°C-Detector Temperature, Oven

Temperature i-35°C, Oven Time i-15 Minutes,

Oven Rate i-1°C/Min, Oven Temperature ii-

60°C, Oven Time ii-20 Minutes, Oven Rate ii-

2°C/Min, Oven Temperature iii-210°C, Oven

Time iii-10 Minutes, Total Time-145 Minutes,

Oven Max-265°C.

2.2. Motor gasoline blended with Superior

Kerosene by Volume for analysis.

1- MG100% – (Standard motor gasoline

sample). 2-Blend-i – (MG98% + SK2%).

3-Blend-ii – (MG96% + SK4%). 4- Blend-iii-

(MG94%+ SK6%). 5- Blend-iv – (MG92%

+ SK8%). 6- Blend-v- (MG90% + SK10%).

7-SKO-100% (Superior Kerosene sample)

Result and Discussion

Carbon by group

The carbon by group data obtained from

Gas Chromatogram showed that the motor

gasoline sample with identity 1, 2, 3, 4, 5,

& 6 of Aromatic, IsoParaffin’s, Napthenes,

olefins and Paraffins imparts little intensifying

and declining in all groups refer (Table 1 and

Figures 1 to 6). But the C-15 plus (carbon

number) have been rising clearly in 2,3,4,5

& 6, which is blended with superior kerosene

of 2, 4, 6, 8 and 10% respectively. This C-15

is not present in the standard motor gasoline

sample; and this data cannot be taken into

account since the quantity is very minor.

J.Balakrishnan et al., J. Appl. Chem. Res., 19, 4, 40-48 (2011) 43

Table1. Carbon by group-Volume percentage.

Group 100% MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v 100% SKO

Identity 1 2 3 4 5 6 7

Aromatics 29.387 29.405 29.440 29.572 29.705 29.942 35.492

I-Paraffin 41.606 41.304 41.300 41.177 41.05 40.404 20.385

Napthenes 6.031 6.043 6.059 6.058 6.109 6.145 7.171

Olefins 11.283 11.255 11.215 11.156 11.063 10.987 8.125

Paraffin 11.226 11.458 11.768 12.042 12.669 12.711 24.080

C15-Plus 0.000 0.046 0.047 0.048 0.049 0.050 4.919

Figure 1. GC data of MG and its blend with Summary by Group-Aromatics.

Figure 2. GC data of MG and its blend with Summary by Group-I-Paraffin’s

Figure 3. GC data of MG and its blend with Summary by Group-napthenes

Figure 4. GC data of MG and its blend with Summary by Group-Olefins

Figure 5. GC data of MG and its blend with Summary by Group-Paraffin’s

Figure 6. GC data of MG and its blend with Summary by Group-C15 Plus

1 2 3 4 5 6

29.39 29.41 29.4429.57

29.71

29.94AROMATICS

1 2 3 4 5 6

41.6141.31 41.30 41.20 41.10

40.41

I-PARAFFINS

1 2 3 4 5 6

6.031 6.0436.059 6.058

6.109

6.145NAPTHENES

1 2 3 4 5 6

11.28 11.2611.22

11.16

11.0610.99

OLEFINS

1 2 3 4 5 6

11.2311.46

11.7712.04

12.67 12.71

PARAFFINS

1 2 3 4 5 6

0

0.046 0.047 0.048 0.049 0.05C-15-Plus


Carbon by number

The data obtained from the carbon by number

clearly reveal that the carbon-5,6,7,8,9,10,11

are going away, while at the same moment time

carbon-12,13,14,15 are amplified as quantity

of superior kerosene increased refer-(Table 2

and Figures 7-10). This data gives information

an that motor gasoline is contaminated with

high carbon content. The fine change in C12 to

C15 apparently indicates that motor gasoline

should be contaminated with high carbon

content which is superior kerosene.

Table2. Carbon by number-Volume percentage.

Carbon number 100% MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v 100%

SKO Identity 1 2 3 4 5 6 7

C4 1.373 1.360 1.355 1.339 1.273 1.271 0.000

C5 22.469 22.404 22.348 22.269 21.735 21.445 0.000C6 20.026 19.842 19.725 19.585 19.013 18.892 0.000C7 25.233 24.892 24.875 24.505 23.953 23.814 0.612 C8 20.791 20.449 20.264 20.136 19.863 19.886 3.235 C9 7.382 7.357 7.423 7.505 7.681 7.965 10.384C10 2.576 2.743 3.043 3.375 3.825 4.234 23.850C11 0.081 0.198 0.401 0.490 0.739 0.994 12.218C12 0.000 0.122 0.120 0.342 0.534 0.720 11.047C13 0.000 0.066 0.123 0.192 0.306 0.381 5.111 C14 0.000 0.054 0.104 0.166 0.217 0.266 2.474 C15 0.000 0.000 0.048 0.078 0.108 0.172 4.747

Figure 7. GC data of MG and its blend with Composite by Carbon-C12




1 2 3 4 5 6

00.122 0.120

0.342

0.5340.720

C 12

1 2 3 4 5 6

00.066

0.1230.192

0.3060.381

C 13

1 2 3 4 5 6

00.054

0.1040.166

0.2170.266

C 14

1 2 3 4 5 6

0 0

0.0480.078

0.140.172

C 15


Carbon by Component-Paraffins

We choose Paraffins content only. It is tedious

to explain the entire individual components.

Standard motor gasoline chromatogram data

showed that the individual component from

n-Butane to n-Decane. But motor gasoline

blends clearly showed that the extra components

like Undecane, Dodecane, Tridecane Tetradecane

and C-15 plus9 (Undecane-is NormalCarbon-nC11,

Dodecane is Normal Carbon-nC12, Tridecane-is

Normal Carbon-n C13, Tetradecane- is Normal

Carbon-n C14 and C-15 plus) with addition of 2%,

4%, 6%, 8% and 10% superior kerosene respectively

(Table 3 and shown in Figures 11-15). Table 3. Carbon by component-Paraffins-Volume percentage

Component Paraffins 100% MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v 100% SKO

Identity 1 2 3 4 5 6 7n-Butane 0.735 0.716 0.700 0.696 0.692 0.686 0.000 n-Pentane 3.702 3.662 3.641 3.549 3.515 3.479 0.000 n-Hexane 2.796 2.765 2.747 2.729 2.652 2.632 0.000 n-Heptane 2.432 2.395 2.385 2.361 2.309 2.295 0.171 n-Octane 1.230 1.221 1.224 1.227 1.230 1.232 0.828 n-Nonane 0.259 0.309 0.353 0.405 0.466 0.507 2.616 n-Decane 0.105 0.160 0.223 0.286 0.358 0.416 3.930

n- C11 0.000 0.079 0.156 0.233 0.309 0.377 4.920 n- C12 0.000 0.071 0.132 0.220 0.241 0.354 4.289 n-C13 0.000 0.066 0.123 0.192 0.260 0.321 4.025 n- C14 0.000 0.054 0.104 0.166 0.217 0.266 2.474 C 15+ 0.000 0.000 0.048 0.078 0.14 0.172 4.747

Figure 11. GC data of MG and its blend with Components-n-Decane.

Figure 12. GC data of MG and its blend with Components-n-Undecane.

Figure 13. GC data of MG and its blend with Components-n-Dodecane.

Figure 14. GC data of MG and its blend with Components-n-Tridecane.

1 2 3 4 5 6

0.1050.160

0.2230.286

0.3580.416

n-DECANE

1 2 3 4 5 6

00.079

0.1560.233

0.3090.377

n-UNDECANE

1 2 3 4 5 6

00.061

0.1200.195

0.2510.314

n-DODECANE

1 2 3 4 5 6

00.066

0.1230.192

0.2600.321

n-TRIDECANE


Calculated Octane number

There is no great distinction in the octane

numbers of motor gasoline and its blends

(Table 4 and shown in Figure 16).

Calculated boiling point-volume % by GC

There is only small deviation in boiling point

(Distillation) obtained by Gas chromatography

starting from IBP (initial boiling point) to 50%

but variation occurs from 70% to 90% and

FBP (final boiling point) (Table 5 and Figure

Figure 15. GC data of MG and its blend with Components-C-15.

1 2 3 4 5 6

0 0

0.0480.058 0.062

0.072

C 15+

Table 4. Calculated Octane number-Volume percentage.

Carbon number 100% MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v 100% SKOIdentity 1 2 3 4 5 6 7

Research Octane Number 86.39 86.47 86.73 86.75 86.78 86.95 59.28

Motor Octane Number 77.95 77.33 77.33 77.15 76.86 76.50 40.53

Figure 16. GC data of MG and its blend with Ron & MON.

1 2 3 4 5 6

86.39 86.47 86.73 86.75 86.78 86.95

77.95 77.33 77.33 77.15 76.86 76.50

RON MON

17). It is evident that the motor gasoline is

adulterated with high carbon content namely

superior kerosene. 10%, 30%, 50%, 70%, 80%

and 90% is the temperature at which volume

of liquid recovered respectively.


Calculated physical properties

The calculated physical properties like Average

molecular weight, Average specific gravity,

Average API gravity, Reid vapour pressure,

Total Hydrogen and Carbon Hydrogen ratio

data’s showed the dissimilarity while the

fraction of superior kerosene content increased

and it is vital tool for adulteration (Table

Table 5. Calculated Boiling Point by GC-Volume percentage.

Component 100% MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v Distillation* 1 2 3 4 5 6

IBP 139.4 139.4 139.5 139.6 139.8 140.0

10% 161.2 160.8 160.9 161.0 159.9 161.0

30% 163.6 163.3 163.6 163.6 163.8 164.9

50% 198.8 198.8 198.9 199.0 199.5 201.9

70% 239.2 239.8 239.8 243.2 244.4 244.7

80% 270.4 270.4 269.7 268.0 265.3 262.6

90% 281.85 282.3 283.0 284.3 301.0 303.9

FBP 381.9 385.5 393.5 404.8 405.1 414.9*Temperature is measured in Fahrenheit unit.

Figure 17. GC data of MG and its blend with Boling point (Distillation) by Volume %.

139.34 161.21 163.62 198.77 239.23 270.41 281.85381.91

139.40 160.80 163.33198.83

239.83 270.35 282.34

385.48

139.49 160.85 163.55198.89

239.78269.71 283.02

393.51

139.59161.01 163.64

198.95243.17

267.98 284.30

404.81

139.84159.85 163.79

199.49

244.41265.26

300.98

405.12

139.95160.95 164.91

201.93

244.68262.58

303.89

414.91

IBP 10% 30% 50% 70% 80% 90% FBP

Boiling point by Volume% GC

Series6 Series5 Series4Series3 Series2 Series1


6). E200 and E300 is the volume of liquid recovered at 200 and 300oC respectively.

Table 6. Calculated Physical Properties-Volume percentage.

Carbon number

100%

MG Blend-i Blend-ii Blend-iii Blend-iv Blend-v 100%

SKO

Identity 1 2 3 4 5 6 7

Avg MW 91.95 91.65 92.72 92.75 92.89 93.93 110.27

Avg SG 0.739 0.740 0.742 0.743 0.743 0.744 0.579

Avg

[email protected] 62.32 62.08 61.94 61.55 61.35 61.24 34.651

Reid Vapour

Pressure[ psi] 6.89 6.76 6.80 6.76 6.66 6.58 0.405

Tot H 13.33 13.29 13.25 13.21 13.17 13.13 9.107C/H 6.48 6.49 6.50 6.50 6.51 6.51 6.90

Recovery @

200[E200] 50.56 50.58 50.55 50.48 50.23 48.97 19.57

Recovery @

300[E300] 91.72 91.63 91.46 91.20 89.72 89.06 37.19

Table7. Indian standards Motor Gasoline Fuel Specification (3rd Revision) [16].

Serial Number Parameters

Requirements (MG)Methods of Test

Unleaded Regular

Unleaded Premium

1 Colour Orange Red Visual 2 [email protected]/m3 720-775 720-775 BIS-P16

3 Olefin content, percent by volume, Max 21 18 ASTM D 1319

4 Aromatics content, percent by volume, Max 42 42 ASTM D 1319

Conclusion

Detailed Hydrocarbon Analysis (DHA) software

is useful for the detection of motor gasoline

adulteration. Gas chromatograph coupled with

DHA software is a wonderful source of analytical

technique for the detection of motor gasoline

adulteration. From the data analysis, it is evident

that the motor gasoline sample is adulterated

with High carbon content (superior kerosene)

which can be visualised by Gas Chromatogram.

Hence it is practicable to clearly know the source

of adulteration of motor gasoline using Detailed

Hydrocarbon Analysis (DHA).

Acknowledgement

we thank Mr.R.Balasubramanian and Mr.J.


Janakiram for gas chromatograph instrumental

analysis and support in analysing the Gas

Chromatogram data

References

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http://www.library4science.com.

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Chemical test methods of analysis, Elsevier,

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theory in analytical chemistry, Wiley, New

York (1994)

[4] B.L.Milman. Chemical identification and

its quality assurance, (2011).

[5] H. H. Schobert, The chemistry of

hydrocarbon fuels, Butterworth, London

Elsevier Ltd (1990).

[6] F.S.De Oliveira, L.S. Gomes Teixeira,

M.C.Ugulino Araujo and M. Korn, Screening

analysis of type C Brazilian gasoline by gas

chromatography flame ionization detector,

Fuel, 917-923, (2004).

[7] D.L. Flumignan, F.O. Ferreira and

F.S.De Oliveira, Screening brazilian C

gasoline quality, Application of the SIMCA

chemometric method to gas chromatographic

data, Analytica Chimica Acta,128-135, (2007).

[8] C.Rita, C.Pereira, V.L.Skrobot,

V.R.Eustaquio, C.Isabel and M.D.Vânya,

Determination of gasoline adulteration

by principal components analysis linear

Discriminant analysis applied to FTIR, Spectra

Energy Fuels, 1097–1102, (2006).

[9] L.S.M.Wiedemann, L.A.d’Avila and

D.A.Azevedo, Adulteration detection of

brazilian gasoline samples by statistical

analysis, Fuel, 467–473, (2005).

[10] E.V.Takeshita, R.V.P.Rezende, S.M.A.

Guelli and U. de Souza, Influence of solvent

addition on the physicochemical properties of

Brazilian gasoline, Fuel, 2168-2177, (2008).

[11] R John.Huges.The storage and handling

of petroleum liquids 2nd Edition (1970)

[12] F.F.P.Almeida, C.A.L.Cardoso, L.H.

Viana, T.Q.Silva, J.L.C. Souzaand and V.S.

Ferreira, Screening analysis of type C Brazilian

gasoline by gas chromatography Flame

ionization detector, Fuel, 418-423,(2009).

[13] G.James Speight and Ozum.Petroleum

refining processes, Marcel Dekker Inc, New

York (2002).

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(1990).

[15] B.K.Bhaskara Rao. Modern Petroleum

Refining Process Oxford & IBH Publishing

Co. Pvt Ltd New Delhi, 5th Ed (2008).

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Standards, NEW DELHI 110002, INDIA.IS–

1448(2002).

Journal of Applied Chemical Research, 19, 49-57 (2011)



The operating of the niccolite ore and nickel extraction of it by DMG in ammoniacal media

Anita Abedi

Department of Chemistry, North Tehran Branch, Islamic Azad University, Tehran, Iran (Received 05 May 2011; Final version received 10 August 2011)

AbstractIn this research, a niccolite mineral (NiAs) contained ore, which is mined in Iran, was studied using XRD method and reflection microscope. Nickel separation from this ore was performed by dimethylglyoxime DMG in methods “A”, “B” and “C” at two classes I and II. Method “A” is usual technique of nickel dimethylglyoxime complex formation and appears competive with two new methods, called “B” and “C”. In method “B”, DMG is consumed directly in solid state without dissolving. In method “C”, DMG is dissolved in ammonium hydroxide solution before used. If the value of iron in the sample is low, three methods in class I are researchable, otherwise Class II for methods is used which has a preliminary step of iron elimination. The advantages and disadvantages of the methods are discussed.Keywords: Dimethylglyoxime; Nickel; Niccolite; Ammonia.

Introduction

The total content of nickel is greater than

combined content of copper, zinc and lead, but

relatively few known nickel recovery available

that are common and economic [1]. The design

of new methods that reduce the extraction steps

and consum materials helps nickel extraction

industries, which can be economical [2].

Nickel occurs along with As, Cu, Fe, Co, Ba,

Si, S, Al, Ca, Mg and etc. Among complexing

agents that have been employed for nickel,

dimethylglyoxime (DMG) has gained wider

use for long time [3-7] and the reaction is

carried out in aqueous alkaline medium [8,9].

The mechanism of the reduction of Ni(II) in

the presence of DMG has been investigated

[10,11]. Other ions such as Cu2+, Co2+ and Fe2+

react also with DMG in alkaline media yielding

stable complexes thus leading to interferences

in the nickel determination [12,13].

In this research, an ore containing niccolite

mineral (NiAs) mined in Iran (Talmesi, Es-

fahan) has been studied and its elements and

minerals are determined using XRD and XRF

[14]. The purpose of this paper is the presen-

tation of this ore considering crystallography

* Corresponding author. Tel.: +98 2122262563; Fax: +98 2122222512, P. O. Box: 19585-936 E-mail address: [email protected] (A. Abedi).

Anita Abedi et al., J. Appl. Chem. Res., 19, 49-57 (2011) 51

and also nickel recovery. Three methods in 2 classes are used. We aimed to reach optimum results by changing the DMG usage condition. DMG is often used as selective complexing agent of nickel but the common procedure is very long method with high amount of con-sumed reagents. We tried to make it short and economical.

Experimental

Materials

The solution was prepared with freshly

deionized water and analytical reagent grade

chemicals. All chemicals including NH3, DMG

dimethylglyoxime, HCl, ethanol and ete were

purchase from Merck Company, Germany.

Methods

The X-ray studied were performed on a

Philips PW 1830 diffractometer (XRD) using

Cu Ka (λ = 0.15418 nm) and a Philips PW

1480 spectrometer (XRF). The picture of ore

was pictured on a transmission and reflection

polarizing microscopes (ZEISS Jenapol).

Atomic Absorption Spectrometry (AAS)

measurements were performed on Varian (Palo

Alto, CA, USA). Spectrometer was equipped

with Zeeman GTA-100 background correction

and a PSD-100 programmable sample dispenser.

All of the measurements were re-examined by

JY-170 (Jobin-Yvon, France) ULTRACE ICP-

AES. All values and percentage of element

were reported considering a maximum error of

±2% in the absorbance reading.


1- Identification of Ore

The identification of ore was performed by two

instruments:

1-1 X-ray diffraction

XRD, X-ray diffraction is used to identify

minerals, metals and any compounds that are

crystallized in crystalline system. Figure 1

shows X-ray diffraction spectrum of titled

ore that contains quartz SiO2, nickeline NiAs,

domeykite Cu3As, barite BaSO4, covellite CuS

minerals. X-ray fluoresce also identified the

presence of Fe, Co, Al, Mg, K, Ca, Sr and ete

(not included).

Fig. 1 X-ray diffraction spectrum Figure 1. X-ray diffraction spectrum.

1-2 Reflection microscope

Mineral identification by microscope was

done by microscope, depending on nature of

the ore. If the thin layer of ore is transparent,

light microscope was employed. Otherwise, if

ore contains metal minerals, it is examined by

reflection microscope. The titled ore contains

metal minerals, so it was identified by reflection

Anita Abedi et al., J. Appl. Chem. Res., 19, 49-57 (2011)52

microscope. Very strong anisotropy and high

reflection of nickeline (niccolite) mineral are

the specifications of this ore. The picture by

reflection microscope is shown in Fig. 2. The

black part in the middle of picture is related to

niccolite mineral.

Fig. 2 The picture of ore by reflection microscope in

fifty times as many at L.P light Figure 2. The picture of ore by reflection microscope in

fifty times as many at L.P light

2- Acid washing of ore

Nickel was separated from the ore by HCl and

HNO3 acid washing, which not only convert

the total nickel to liquid phase but also delete

arsenic as the volatile substrate AsCl3 [2,11].

The metal minerals are dissolved in these acids

and the nickel as wellas copper, cobalt, iron

arsenic and etc, and BaSO4 and SiO2 which

consistalmost 50% of ore, remain in solid phase

and separated by filtering. The procedure was

as follow:

100 g of ore is transferred to 1000-mL beaker

and 100 mL of concentrated hydrochloric acid is

added and is boiled until that the sample is dry.

In this stage arsenic as the volatile compound

AsCl3 exits [15]. Then 200 mL concentrated

nitric acid was added and heated gently until

brown fumes are emitted and the solution

volume reached to half. Then it was filtered and

the solution was diluted by water until 250 mL

(solution 1). The filtrate solid contained BaSO4

and SiO2 minerals.

The amount of Ni, Cu, Co and Fe in solution

1 (in 100 g of ore) were determined by atomic

absorption spectrometry and the percentages of

these elements in the ore is reported (Table 1).

Table 1. Elements percent in ore

Element Ni Cu Co Fe

g in 100 g ore or in solution 1 10.137 5.300 0.161 0.087

3- Nickel separation by precipitation with

dimethylglyoxime

The method “A” is a routine method for the

the determination of Nickel with the alcoholic

solution of dimethylglyoxime which is used for

comparison with methods “B” and “C”.

In class I, the sample is not filtered after

ammonium hydroxide addition, supposedly it

is diluted with water to ten time, but in class

II, the ammoniacal sample is filtered, as all of

iron is precipitated as rust solid Fe(OH)3. In this

manner, some nickel is also co-precipitated, but

washing by concentrated ammonium hydroxide

will pass nearly half of the precipitated nickel

to solution but not any iron.

3-1 Class I

In class I methods, to 10 mL solution 1, the


sufficient (60 mL) 1:10 ammonium hydroxide

solution is added to make alkaline solution

(pH =9) and this solution is dilute with

water by 10 times (solution 2), where the

ammoniacal precipitate becomes very fine

dispersed particles. The elements existed in

solution 2 are according to Table 2. Then the

nickel recovery of solution 2 is performed by

methods “A”, “B” and “C” as below.

Table 2. Values of elements in solution 2

Element Ni Cu Co 1. Fe

mg in solution 2 405.49 212.00 6.44 3.48

3-1-1 Method “A”

This method is the common method of DMG

using for nickel separation in liquid phase. Based

on this method, nickel separation from liquid

phase is done according to procedure below:

9 mL acetic acid solution (1:10) is added to

Solution 2 that makes it acidic (pH=4) and 250

mL 1% alcoholic DMG is used to precipitate

all the nickel in the sample. Then solution

becomes distinctly alkaline by ammonium

hydroxide solution and after 24-hour fine

nickel DMG complex is filtered.

The total elements of the filtrate are detected

and measured. The amount of separated and

wasted elements from solution 2 is shown in

Table 3.

Table 3. Values of separated elements at method "A" in class I

Element Ni Cu Co Fe 1) separated element2) wasted element (mg) 3) % Separated element in the ratio of its value in solution 2 4) % Separated element in the ratio of total separated elements in row 1

378.5127.0093.3

91.0

34.95177.04

16.5

8.4

0.026.410.3

0.00

2.281.2165.3

0.6

3-1-2 Method “B”2.5 g dimethylglyoxime is added to the solution 2, and after 24 hours nickel-DMG

complex is filtered. With this method, the amount of resolution elements of solution 2 is summurized in Table 4.

Table 4. Values of separated elements at method "B" in class I

Element Ni Cu Co Fe

1) separated element (mg) 2) % Separated element in the ratio of its value in solution 2 3) % Separated element in the ratio of total separated elements in row 1

358.5788.496.2

12.836.1 3.4

0.040.6

0.00

1.3538.70.4


3-1-3 Method “C” 2.5 g DMG was dissolved in 250 mL concentrated ammonium hydroxide and added

to solution 2. The precipitated complexes were filtered after 24 hours. The results are listed in Table 5.

3-2 Class IIIn class II methods, to 10 mL solution 1, sufficient (60 mL) 1:10 ammonium hydroxide solution is added to make it alkaline solution (pH =9) and the ammoniated precipitate is

But re-precipitation of ammoniated, precipitate

(0.5 g) by concentrated ammonium hydroxide

will pass is nearly half of the precipitated nickel to

filtrate solution (and not any iron). The quantities

of converted elements to filtrate are shown in

row 3 and the returned elements percentage ratio

is displayed at row 4 of the table.

This filtrate solution is added to the first filtrate

solution and the total values of elements in

class II (solution 3) are shown in row 5. It

means that the solution 3 (row 5) is the sum

of row 1 and 3.

3-2-1 Method “A”

8 mL acetic acid solution (1:10) was added

to solution 3, to made it acidic (pH=4) and

250 mL 1% alcoholic DMG was added to

precipitate all the nickel. Then the solution

was made distinctly ammoniated and after 24-

hour, the precipitate is filtered. The amount of

separated and wasted elements f rom solution

3 is shown in Table 7, rows 1 and 2.

Table 5. Values of separated elements at method "C" in class I

Element Ni Cu Co Fe 1) separated element (mg) 2) % Separated element in the ratio of its value in solution 2 3) % Separated element in the ratio of total separated elements in row 1

394.5297.3

98.5

5.61 2.6

1.4

0.02 0.3

0.00

0.5214.9

0.1

filtered (0.5 g). This method precipitates all of iron the and part of nickel. The remained amounts of elements in filtrate and ammoniated precipitate (0.5 g) are brought in Table 6 (rows

1 and 2).

Table 6. Values of elements for preparing solution 3

Element Ni Cu Co Fe 1) element in ammoniacal filtrate solution 2) element in ammoniacal precipitate (0.5 g) (mg) 3) returned element from precipitate (0.5 g) (mg) 4) % Returned element in the ratio of its value in precipitate (0.5 g) 5) element in solution 3 (mg)

284.78120.7152.0643.1

336.84

152.9259.1021.4136.2

174.33

0.026.400.8613.4

0.88

0.043.440.000.0

0.04


Table 7. Values of separated elements at method "A" in class II.

Element Ni Cu Co Fe 1) separated element (mg)2) wasted element (mg) 3) % Separated element in the ratio of its value in solution 2 4) % Separated element in the ratio of total separated elements in row 1

320.7716.0679.1

91.4

30.06144.27

14.2

8.6

0.010.860.2

0.0

0.030.010.9

0.0

3-2-2 Method “B”

Method “B” in class II is similar to method

“B” in class I and it is as follow:

2.5 g dimethylglyoxime is added to solution

3, after 24-hour nickel dimethylglyoxime

complex is filtered. Table 8 shows the results

in solution and precipitation.

Table 8. Values of separated elements at method "B" in class II

Element Ni Cu Co Fe 1) mg separated element 2) % Separated element in the ratio of its value in solution 2 3) % Separated element in the ratio of total separated elements in row 1

295.3372.8

96.3

11.295.3

3.7

0.020.3

0.0

0.010.3

0.0

3-2-3 Method “C”

2.5 G DMG was dissolved in 250 mL

concentrated ammonium hydroxide and added

to solution 3. The nickel- DMG complex is

formed and after 24-hour filtered (Table 9).

Table 9. Values of separated elements at method "C" in class II

Element Ni Cu Co Fe 1) separated element (mg)2) % Separated element in the ratio of its value in solution 2 3) % Separated element in the ratio of total separated elements in row 1

330.2681.4

99.0

3.25 1.5

1.0

0.03 0.5

0.0

0.000.0

0.0

Conclusion

All the measurements are based on using

AAS and are predetermined by ICP. In the

all methods for generation of the nickel

dimethylglyoxime complex formation, mixture

was left for 24 hours and then filtered. Since

the most significant interferences for the

nickel determination with DMG are Cu2+,

Co2+ and Fe2+ that produce stable complexes

with the organic reagent, (DMG) [12], these

ions are examined in all methods, with Ni2+.

The elements of the precipitated complexes

were measured by dissolving of the precipitate

in HCl2 2M and converting nickel and other

metal ions from solid to liquid phase and

filtrate solution were analyzed.


We looked for the method with least stages

and reagents consumption and high nickel

recovery yield. Method “A” consumes 20

mL acetic acid solution (1:10), 2.5 g DMG,

250 mL ethanol and 20 mL 1:10 ammonium

hydroxide solution (for solution 2 in class I

and solution 3 in class II).

In method “B”, only 2.5 g dimethylglyoxime

and in method “C”, 2.5 g dimethylglyoxime

and 250 mL concentrated ammonium

hydroxide solution is consumed. There for

methods “B” and “C” show preference to

If the content of iron is low similar to the

titled ore, method “C” is responsible in nickel

extraction operating with relatively iron

elimination of 85%. But if iron exists in high

quantity or if a slight amount of iron interferes

in nickel consumption, iron must be initially

eliminated from the solution. As it was

explained in term of class II, in which nickel-

contained solution needs to be made ready to

method “A”; “B concidering the consumed

materials and recovery steps and “C”

concidering the recovery steps, separated

nickel and elimination other ions, especially

copper. As it is shown in chart 1 and 2,

method “C” enables almost complete nickel

separation and copper elimination so that the

final solution by method “C” contains almost

99% Ni and 1% Cu (line 3 in Table 5 and 9).

This also is true for iron elimination. Each of

the three methods are successful for cobalt

elimination (chart 1).

Chart 1. Separated element percent relative to its value in solution 2 in class I series1: Method "A" ; series2: Method "B" ; series 3: Method "C"

Ni Cu Co FeS1

S30

20406080

100

Series1Series2Series3

employ methods “A”, “B” and “C”. In this

preliminary state, all the iron, 17% nickel, 18%

copper and 86% cobalt is eliminated (chart 2).

This means that in class II, 17% nickel was

rejected in preliminary state but the advantage

of this class is its high percentage of nickel

recovery compared to the other separated

elements (compare lowest line in class II with

lowest line in class I).


The selection of method “B” or “C” at two-

noted class es depends on our condition. If

the preference is the reduction of consumed

reagents and separation steps, method “B”

can be used. Method “B” provides another

advantage; half of the consumed DMG be

recovered after dissolving NiDMG in 2 M HCl

and filtering, and the filtered solid is useable

DMG. If the preparation of nickel solution

of higher purity is reguired, then method “C”

can be applied. So method “A” does not offer

special advantage compared with methods

“B” and “C”.

Acknowledgement

The author is grateful to Atomic Energy

Organization of Iran for preparation of

niccolite containing ore and Islamic Azad

University North Tehran Branch for financial

support.

References

[1] M. Korolczuk Talanta 53, 3, 679 (2000).

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Microchem. J. 63, 3, 365 (1999).

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15, 2035 (1999).

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Microchem. J. 63, 365 (1999).

[10] W. Jin, K. Liu, J. Electroanal. Chem.

216, 181 (1987).

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[13] M. Halmann, D. -W. Lee, Anal. Chim.

Acta 113, 383 (1980).

[14] M. Tarkian, W. D. Bock, M. Neumann,

Chart 2. Separated element percent relative to its value in solution 2 in class II Series1: Method "A", Series2: Method "B", Series 3: Method "C"

Ni Cu Co FeS1

S30

20406080

100

Series1Series2Series3


Tschermaks Min. Petr. Mit. 32, 111 (1988).

[15] S. N. Jabr, App. Optics, 24, 11, 1689

(1985).

[16] A. Majumdar Ann. Rev. Mat. Sci. 29, 505

(1999).

[17] D. W. Ward, K. A. Nelson, K. J. Webb,

New J. Phys. 7, 213 (2005).

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Julshamn, AOAC Int. 82, 5, 1217 (1999).

[19] P. Junnila, M. Latvala, R. Matilainen,

J. Tummavuori, J. Anal. Chem. 365, 4, 325

(1985).

[20] S. Ramirez, G. J. Gordillo, D. Posadas, J.

Electroanal. Chem. 431, 2, 171 (1997).




Density Functional Theory Study of Magnesium Hydride Nano Clusters

Roya Majidi*

Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran.

AbstractWe have performed the Density Functional Theory calculations to study the small clusters of magnesium hydride. The MgH2 clusters consisting of up to four magnesium atoms have been considered, (MgH2)n (n=1-4). Total energy, binding and desorption energies, dipole moment, and atomic charge have been reported. Our results indicate a decrease in binding energy and an increase in desorption energy with increasing the cluster size. From calculated energies, it is clear that as the cluster size increases, the structure becomes more stable. We have systematically investigated the electronic properties, and the energy band gap between the highest occupied and the lowest unoccupied molecular orbital.Keywords: Magnesium Hydride Nano Clusters, Density Functional Theory.

IntroductionThe applicability of metal hydrides as drying and reducing agents in solution chemistry, and hydrogen storage media in automotive industry, and etc. has been the focus of intensive research [1, 2]. Among the metal hydrides, magnesium hydride is one of the most attractive hydrogen storage substance, due to its high hydrogen storage capacity (7.6 wt.%), light weight, and low manufacturing cost [3, 4]. However, its practical applications for hydrogen storage are limited because of its slow hydrogen absorption/desorption kinetics, high dissociation temperature (nearly 300 ºC), low plateau pressure at ambient temperature,

and the high thermodynamic stability [5, 6, 7]. During the last two decades, many efforts have been employed to overcome those drawbacks, including mechanical ball milling, mechanical alloying, or surface modification of Mg [8, 9, 10]. Many of these techniques can only improve adsorption and not desorption kinetics, because even the smallest particle sizes obtained by these methods (20 nm) still primarily display bulk desorption characteristics [11-13]. Although some alloying or doping techniques can affect the desorption temperature, this is accompanied by a lower hydrogen storage capacity due to the added weight [14, 15]. Recently, theoretical calculations indicate a steep increase in heat of

* Corresponding author. Roya Majidi, Department of Physics, Shahid Rajaee Teacher Training University Young Researches Club, Karaj, Iran E-mail address: [email protected], Tel: (9821)29902770 Fax: (9821)22431666

Roya Majidi et al., J. Appl. Chem. Res., 19, 58-65 (2011)60

investigate the nano Mg/MgH2 systems, and a systematic study on the geometry, stability, and electronic properties of the small MgH2 clusters is clearly useful. In this paper, Density Functional Theory (DFT) method is used to study the stability and electronic properties of the small clusters of (MgH2)n with n=1-4.

MethodThe DFT calculations were performed using GAUSSIAN 03 [18]. We considered the small (MgH2)n clusters with n=1-4, where n is the number of magnesium atoms in the cluster. The used functional is B3LYP, which is the combination of Becke’s 3-parameter exchange functional with Lee-Yang-Parr correlation energy functional [18-21]. We chose the 6-31G(d) basis set in all calculations [18, 22, 23]. The HyperChem software has been used to create molecular structures and to draw Fig. 1 [24].

formation and decrease in structural stability as particle size drop below 1.0 nm [13, 16]. This finding agrees with ball milling experiments that suggest, there is little change in the heat of formation even when particle size is reduced to the 20-100 nm regime. Therefore, the particle size has to be reduced substantially below 20 nm range to see a significant drop in particle stability [13]. Li et al. showed experimentally that thinner Mg/MgH2 nanowires have much lower desorption energy than that of thicker nanowires or bulk Mg/MgH2, indicating that changes in kinetics and thermodynamics is expected if the diameters of the nanowires are lower than 30 nm [3]. The experimental results indicated that Mg nano/mesoscale (spheres, flakes, rods, and sea urchninlike) structures have shown promising properties for application in Mg/air batteries [17]. These promising results have stimulated many research groups to

Fig 1

Fig 2 Fig 3

Figure 1. Optimized geometries of (MgH2)n clusters, n=1-4. The values in parentheses are atomic charges. Boms lenghts are in A.

Roya Majidi et al., J. Appl. Chem. Res., 19, 58-65 (2011) 61


1- Geometries and Binding Energies

The geometry optimization has been done on

initial molecular structures to find configurations

with minimum of energy. Fully relaxed

geometries of magnesium (MgH2)n clusters for

n=1-4 are shown in Fig. 1. In this figure,

some of the isomers for each cluster size and

their point symmetry group are shown. The

chain C2v, hat-like C2v, and planar cyclic D3h

structures were considered for n=3. When

n=4, there are five different structures, chain

D2h, cubic transformation C1, string-like C2,

cubic Td, and ring-like C2v. In order to validate

the geometry optimization for our calculation

method, all the structures were compared with

Ref. 19. Our geometries are in good agreement

with the results of this reference. For example,

the bond length of the MgH2 with linear

D∞h structure is 1.707 Å in our study, while

QCISD/6-311G(dp) method yields 1.708 Å

[25]. The average bond length increases with

increasing size of the clusters, and varies from

1.7 to 1.9 Å. It is well known that MgH2 has

the rutile crystal structure in bulk form, and

the experimental bond length of crystalline

MgH2 is 1.95 Å [26].

The binding energy per Mg atom, Ebind is

defined as

Ebind = [E(MgnH2n) - E(MgH2)]/n (1)

for the following reaction

n(MgH2) (MgH2)n (2)

where, E(MgnH2n) is the total energy of the

(MgH2)n cluster. The total and binding energies

per magnesium atom, Etot and Ebind are given in

Table 1.

Table 1. Total energy (Etot), binding enrgy (Ebind), and desorption energy (Edes) per Mg atom, HOMO-LUMO gap energy (Eg) of (MgH2)n clusters derived by B3LYP/6-31G(d). Energies are in (eV).

n symmetry Etot Ebind Edes Eg

1 D∞h -5476.70 0.0 -0.175 6.212 D2h -5477.31 -0.616 0.608 5.423 D3h -5477.49 -0.796 0.580 5.17

chain C2v -5477.55 -0.856 0.895 5.01hat-like C2v -5477.47 -0.771 0.789 5.89

4 D2h -5477.67 -0.973 1.022 5.82C2v -5477.52 -0.824 0.639 5.01C1 -5477.64 -0.937 0.821 5.10C2 -5477.70 -1.007 0.952 5.00Td -5477.63 -0.929 0.616 5.85

The calculation of the energies shows that

(MgH2)3 with chain C2v point of symmetry is

the most stable structure for n=3. The C2 point

of symmetry is more stable than the others for

n=4. The binding energy as a function of the

cluster size is shown in Fig. 2. The results of our


calculations are compared with those derived by

different methods in Ref. 25. This comparison

shows that the B3LYP method leads to energies

that are in reasonable agreement with those

derived by Chen et al [25]. It is clear that the

binding energy depends on the cluster size, and

decreases with increasing the cluster size.

Fig 1

Fig 2 Fig 3

Figure 2. Binding energies as a function of cluster size. For comparison the binding energies computed by the MP2 and QCISD methods in Ref. 19 are shown.

This is what can be expected from first-

principles of physical properties. The surface/

volume ratio increases upon decreasing the

cluster size and below a critical cluster size,

all Mg and H atoms were exposed to the

surface. Since the surface atoms have a lower

coordination, the average number of bonds is

lower for smaller clusters [12, 25].

2- Desorption Energies

Although improvements in the kinetics of

magnesium have been achieved by nanostructing

of particles down to the 20-100 nm regimes, the

conclusions in the changes in the thermodynamics

of these particles with respect to the bulk

magnesium hydride still remain open-ended

[13]. To determine whether size enlarging could

sufficiently destabilize the MgH2 nanoparticles,

we have investigated desorption energy of the

small MgH2 clusters. The desorption energy,

Edes of the following reaction

(MgH2)n Mgn + nH2 (3)

can be written as

Edes = [E(Mgn) + nE(H2) – E(MgnH2n)]/n (4)

Where E(Mgn) and E(MgnH2n) are the total

energies of Mg and MgH2 clusters, respectively

[12]. The calculated desorption energies

are given in Table I. The desorption energy

reduces as the cluster becomes smaller, which

indicates a destabilization of small clusters.

Hence, the small MgH2 clusters can exhibit a

desorption behavior very different from that

of bulk MgH2 [27]. The reduction in Edes for

small clusters indicates a lower equilibrium

desorption temperature for MgH2. This useful

change in physical properties might enable

the use of the Mg for hydrogen storage [12].

We note that the calculated desorption energy

for the smallest possible cluster, MgH2,

is a negative value, which means that the

magnesium hydride molecule is not stable.

3- Atomic Charges

The atomic charges, Q, calculated by Mulliken

population analysis [28], are given in Fig. 1. The

hydrogen atoms in hydride clusters always have negative charges. This implies that the hydrogen


atom always behaves as the electronegative species toward the magnesium atom [25].

4- Dipole Moments The dipole moments of magnesium hydride clusters are also calculated and shown in Fig. 3 as a function of the number of magnesium atoms. Nonzero dipole moments indicate that the electron charge distribution does not always match the ionic charge distribution and can be shifted with respect to the cluster center of mass [29].

Fig 1

Fig 2 Fig 3

Figure 3. Dipole moments for (MgH2)n clusters as a function of cluster size. Dipole moments are in Debye.

5- Electronic Structures Density of states (DOSs) in combination with molecular orbitals (MOs), especially frontier MOs, gives the overall electronic structure and reactivity of a system. The output of the Gaussian has been analyzed by GaussSum 2.4.3 to extract MO information and calculate

DOS [30]. The total DOS and frontier MOs of the MgH2 clusters are shown in Fig. 4. Fig 4


The band gap, Eg, is defined as the difference in energies between the highest occupied (HOMO) and the lowest unoccupied (LUMO) Molecular orbital. Many electrical and optical properties of clusters are directly related to the band gap, thus we have calculated these values. As indicated from Table I, the HOMO-LUMO gap depends on the cluster size and varies from 6.21 to 5 eV. Our results confirm that the MgH2 clusters containing up to four magnesium atoms exhibit insulating behavior. It is well known that MgH2 is an insulator. The experimental and theoretical studies confirmed that α phase of MgH2 (TiO2-rutile-type) exhibit insulating behavior with the band gap of 5.6 and 3.9 eV, respectively [31, 32]. As shown in Fig. 4, the number of states increases with increasing of atoms.

SummaryIn summary, we have used DFT to investigate the magnesium hydride nano clusters, (MgH2)n (n=1-4) to understand their stability and electronic properties. The geometry, binding and desorption energies, atomic charge, and energy band gap were calculated. When n=3, we have studied three kinds of structures. The (MgH2)3 with chain C2v point of symmetry is more stable than others. For n=4, five kinds of structures were considered. The C2 symmetry is the most stable structures. The calculated energies indicate that stability of the clusters decreases as the clusters become smaller. The small MgH2 clusters have a

much lower desorption energy than bulk MgH2 hence enabling hydrogen desorption at lower temperatures. Our results indicate that the MgH2 clusters containing up to four magnesium atoms exhibit insulating behavior and Eg depends on the cluster size.

References[1] T. Vegge, L.S. Hedegaard-Jensen, J. Bonda, T.R. Munter, J.K. NØrskov, J. Alloys. Compd. 386, 1 (2005).[2] L. Schlapbach, A. Züttel, Nature. 414, 353 (2001).[3] W. Li, C. Li, H. Ma, and J. Chen, J. Am. Chem. Soc. 129, 9710 (2007).[4] G. Liang, J. Huot, S. Boily, A. Van Neste, and R. Schulz, J. Alloys. Compd. 292, 247 (1999).[5] J.F. Stampfer, C.E. Holley, and J.F. Suttle, J. Am Chem. Soc. 82, 3540 (1960).[6] W. Grochala, and P.P. Edward, Chem. Rev. 104, 1283 (2004).[7] A.J. Du, S.C Smith, X.D. Yao, and G.Q. Lu, Surf. Sci. 600, 1854 (2006).[8] G. Liang, J. Alloys. Compd. 370, 123 (2004).[9] A. Zaluska, L. Zaluski, and J.O. Ström-Olsen, J. Alloys. Compd. 288, 217 (1999).[10] J. Huot, J.F. Pelletier, L.B. Lurio, M. Sutton, and R. Schultz, J. Alloys. Compd. 384, 319 (2003).[11] G. Liang, J. Huot, S. Boily, A.V. Neste, and R. Schulz, J. Alloys. Compd. 292, 247 (1999).


[12] R.W.P. Wagemans, J.H. van Lenthe, P.E. de Jongh, A.J. van Dillen and K.P. de Jong, J. Am. Chem. Soc. 127, 16675 (2005). [13] S. Cheung, W.Q. Deng, A.C.T. van Duin, and W.A. Goddard III, J. Phys. Chem. A. 109, 851 (2005).[14] K. Higuchi, H. Kajiokam, K. Toiyama, H. Fujii, S. Orimo, Y. Kikuchi, J. Alloys. Compd. 293, 484 (1999).[15] A. Zaluska, L. Zaluski, and J.O. Ström-Olsen, Appl. Phys. A. 72, 157 (2001).[16] W.P. Rudy, R.W.P. Wagemans, J.H. van Lenthe, P.E. de Longh, A.J. van Dillen, and K.P. de Jong, J. Am, Chem. Soc. 127, 16675 (2005). [17] Y.G. Sun, Z.L. Tao, J. Chen, T. Herricks, and Y.N. Xia, J. Am. Chem. Soc. 126, 5940 (2004). [18] Gaussian 03, Revision B.03, M. J. Frisch, G. W. Trucks, et al., Gaussian, Inc., Pittsburgh PA, 2003.[19] A.d. Becke, J. Chem. Phys. 98, 5648 (1993).[20] C. Lee, W. Yang, and R.G. Parr, Phys. Rev. B 37, 1758 (1988).[21] B. Miehlich, A. Sarvin, H. Stoll, and H. Preuss, Chem. Phys. Lett. 157, 200 (1989).[22] G.A. Petersson, and M.A. Al-Laham, J. Chem. Phys. 4, 6081 (1991)..[23] G.A. Petersson, and M. Bennelt, T;G. Tensfeldt, M.A. Al-Lahan, W.A. Shirley, and J. Mantzaris, J. Chem. Phys. 89, 2193 (1988).[24] http://www.hyperchem.com.[25] Y.L. Chen. C.H. Huang, and W.P. Hu, J.

Phys. Chem. A. 109, 9627 (2005).[26] K. Raghavachari, G.W. Trucks, J.A. Pople, and M. Head-Gorden, Chem. Phys. Lett. 157, 479 (1989).[27] L. Zaluski, J. Am. Chem. Soc. 82, 3504 (1960).[28] M. D. Segall, R. Shah, C. J. Pickard, and M. C. Payne, Phys. Rev. B. 54, 16317 (1996). [29] I. A. Solov’you, A.V. Solov’you, and W. Greiner, Phys. Rev. A. 65, 53203 (2002).[30] http://gaussum.sourceforge.net.[31] J. Isidorsson, I.A.M.E. Giebels, H. Arwin, and R. Griessen, Phys. Rev. B. 68, 115112 (2003).[32] C. Moysés Araújo, and R. Ahuja, J. Alloys. Compd. 404, 220 (2005).




Molecular Mechanics Based Study On Molecular And Atomic Orbital Of Nickelocene

G. Khan

Department of Physics, K. S. Saket Post Graduate College, Ayodhya-Faizabad, U.P., India

AbstractThe relative energy levels and magnitude of contribution of atomic orbitals in the formation of molecular orbital (MO) of nickelocene have been studied. The 3D modeling and geometry optimization of nickelocene have been done by CAChe software using molecular mechanics method with EHT option. The nine atomic orbitals which are involved in bonding are one 4s, three 4p and five 3d. The MOs involving d orbital have eigenvalues in the range 0.5462 – 0.2296 eV, i.e. in bonding range whereas 4s and 4p orbitals are in range 0.0713 – 4.2942 eV which antibonding range. The 2pz orbitals of ten carbon atoms of two C5H5¯ are involved in bonding with nine nickel orbitals. The coefficient of eigenvector of 2pz of carbon is in the range 0.3096 – 2.2112 eV. Key words: Nickelocene, molecular orbitals, atomic orbitals, eigenvalues, eigenvector, energy level, population analysis.

* Corresponding Address: Dr. Gayasuddin Khan, Near Hanumangarhi Temple, Chowk Bazar, Balrampur-271201 (U.P.), INDIA Email: [email protected]

Introduction

M (C5H5)2 [M (ep) M = Fe, Co, Ni] are the

derivatives of cyclopentadiene and have a

sandwich structure. They are often called

metallocenes. The structures of metallocene

have been extensively studied and are reported

in most of the organometallic chemistry books

[1, 2]. However the calculations of relative

energy levels and magnitude of contribution of

atomic orbitals in the formation of molecular

orbital (MO) is still a subject of study [2]. In

a recent publication [3] I have evaluated the

contribution of atomic orbitals in cobaltocene

on quantitative basis with the help of

computational chemistry [4]. In this paper a

study on nickelocene has been presented. The

main focus will be on the study of eigenvalues,

eigenvector values and population analysis of

nickelocene.

Exprimental

The study material of this paper is nickelocene.

The 3D modeling and geometry optimization

of nickelocene have been done by CAChe

G. Khan et al., J. Appl. Chem. Res., 19, 66-84 (2011) 67

software [5, 6] using molecular mechanics

method with EHT option [7]. The 3D structure

is shown in the Figure 1. Eigenvalues and

eigenvectors values have been obtained with

the same software, using the same option. The

method adopted for various calculations is

based on following principles.

Figure 1. 3D Structure of Nickelocene

The molecular orbitals are formed by the

linear combination of basis functions. Most

molecular quantum-mechanical methods

(such as- SCF, CI etc.) begin the calculation

with the choice of a basis functions χr, which

are used to express the MOs ϕi as ϕi = Σi cri

χr (c = coefficient of χ, r is the number of

atomic orbital, i = molecular orbital number).

The application of an adequate basis set is an

essential requirement for the calculation. The

basis functions are usually taken as AOs. Each

AO can be represented as a linear combination

of one or more Slater-type orbitals (STOs) [8-

10]. Each molecular orbital ϕi is expressed as

ϕi = Σi cri χr, where, the χr ’s are the STO basis

functions. Here we use the STO–6G basis set

(which is contracted Gaussian) [11-14] for the

SCF calculation.

The coefficients in linear combination for each

molecular orbital being found by solution of

the Roothaan equation [15]. By the above

calculation, the values of orbital energies

(eigenvalues) and eigenvectors (coefficients)

have been calculated.

A widely used method to analyze SCF wave

function the population analysis, introduced

by Mulliken [16, 17]. He proposed a method

that apportions the electrons of an n-electron

molecule into net population nr in the basis

functions χr and overlap populations nr–s for

all possible pairs of basis functions. With the

help of these values magnitude of contribution

of atomic orbital in MO formation, and

population analysis have been made and

discussed.


The molecular orbitals of nickelocene shown

in Figure 1 are formed by linear combination

of 50 atomic orbitals of two C5H5¯ anion and 9

orbital of nickel as detailed in Table 1.

G. Khan et al., J. Appl. Chem. Res., 19, 66-84 (2011)68

Table 1. Atomic orbitals (c) of nickelocene.c Atom AO1 1C 2s

2 1C 2 xp

3 1C 2 yp

4 1C 2 zp

5 2C 2s

6 2C 2 xp

7 2C 2 yp

8 2C 2 zp

9 3C 2s

10 3C 2 xp

11 3C 2 yp

12 3C 2 zp

13 4C 2s

14 4C 2 xp

15 4C 2 yp

16 4C 2 zp

17 5C 2s

18 5C 2 xp

19 5C 2 yp

20 5C 2 zp

21 6C 2s

22 6C 2 xp

23 6C 2 yp

24 6C 2 zp


25 7C 2s

26 7C 2 xp

27 7C 2 yp

28 7C 2 zp

29 8C 2s

30 8C 2 xp

31 8C 2 yp

32 8C 2 zp

33 9C 2s

34 9C 2 xp

35 9C 2 yp

36 9C 2 zp

37 10C 2s

38 10C 2 xp

39 10C 2 yp

40 10C 2 zp

41 11Ni 2s

42 11 Ni 2 xp

43 11 Ni 2 yp

44 11 Ni 2 zp

45 11 Ni 2 23dx y−

46 11 Ni 23dz

47 11 Ni 3dxy

48 11 Ni 3dxz

49 11 Ni 3dyz


50 12H 1s

51 13H 1s

52 14H 1s

53 15H 1s

54 16H 1s

55 17H 1s

56 18H 1s

57 19H 1s

58 20H 1s

59 21H 1s

The 59 atomic orbitals give LCAO

approximation to 59 molecular orbitals.

The eigenvalues of MOs are included in

Table 2.

Table 2. Eigenvalues and MO (f) of nickelocene.

MO(f) Eigenvalues (eV)1 -1.19022 -1.09283 -0.91184 -0.90435 -0.87866 -0.86817 -0.69208 -0.69019 -0.679910 -0.679211 -0.610112 -0.604313 -0.554714 -0.547715 -0.546216 -0.528717 -0.526018 0.521219 -0.5163

20 -0.5139


21 -0.512422 -0.509523 -0.502124 -0.500525 -0.480126 -0.475327 -0.471828 -0.447129 -0.440530 -0.376431 -0.330732 -0.274233 -0.246034 -0.232235 -0.229636 0.071337 0.092238 0.111439 0.138740 0.159641 0.171542 0.191343 0.260144 0.279145 0.280246 0.407247 0.408048 0.430549 0.431150 0.537251 0.742452 0.807853 0.910654 1.111055 1.935756 2.023057 2.245958 2.253959 4.2942


The atomic orbitals (AOs) are represented by χ

and molecular orbitals (MOs) by ϕ . 1-40 χ are

atomic orbitals of carbon, 41-49χ of nickel and

50-59 χ of hydrogen. The orbitals involved in

χ bonding are not interest, hence shall remain

out of the discussion. The 2PZ orbitals of ten

carbons [7] and nine orbital of nickel, i.e. in

total 19 orbitals, are relevant to the discussion

in respect to bonding between nickel orbital

and 2PZ orbitals of C5H5¯. These atomic

orbitals are χ4, χ8, χ12, χ16, χ20, χ24, χ28, χ36, χ40 of

Table 3. Eigenvector values of orbitals of nickel in nickelocene and their summation values.

MOs4s

( 41χ )

4px

( 42χ )

4py

( 43χ )

4pz

( 44χ )

3dx2-y2

( 45χ )

3dz2

( 46χ )

3dxy

( 47χ )

3dxz

( 48χ )

3dyz

( 49χ )ϕ15 0.3209 0.3365ϕ16 0.2294ϕ18 0.3605ϕ19 0.3128ϕ20 0.5297ϕ21 0.3029ϕ23 0.4179ϕ24 0.3849 0.4986 0.2011ϕ25 0.5232 0.3369 0.2396 0.2782ϕ26 0.7408 0.4949ϕ27 0.6697 0.2358ϕ30 0.2979 0.4786 0.3521ϕ31 0.4183 0.4178ϕ35 0.2624ϕ36 0.5037 0.5563 0.2729ϕ37 0.4088 0.3254 0.2960ϕ38 0.6732 0.2423 0.3695ϕ39 0.7569 0.3868 0.3261f40 0.2473 0.2201 0.3706f41 0.4584f42 0.3487 0.3318f43 0.6971 0.7470f50 1.0725

χ41, χ49 carbon and of nickel. The coefficients

of these orbitals are the eigenvector values of

χ which have been evaluated by molecular

mechanics method using CAChe software

[18-19]. They express the forms of molecular

orbital, i.e. the extent of involvement of χ in

the formation of ϕ. These values are included

in Table 3, for metal orbitals and Table 4, for

2pZ orbitals of carbon. The zero or near zero

values have been excluded from the tables.


f52 0.3086 0.2441f53 0.3020 0.2283f54 0.6421 0.4372 0.5633f55 0.2253f56 0.3321f59 0.4436 1.0762 3.1256

Sum

mat

ion

Valu

es

3.376 4.5856 4.9416 4.6366 2.0361 1.3756 1.7279 2.1854 2.3164

N.B.: Orbitals having eigenvector values above 0.20 have only been considered.

Table 4. Eigenvector values of 2pz orbitals of carbon atoms both the C5H5¯ and their summation values:MOs 1C

( 4χ )2C

( 8χ )3C

( 12χ )4C

( 16χ )5C

( 20χ )6C

( 42χ )7C

( 82χ )8C

( 32χ )9C

( 36χ )10C

( 40χ )

ϕ15

ϕ16

ϕ18

ϕ19

ϕ20

ϕ21 0.2019ϕ23 0.2182ϕ24

ϕ25 0.2018ϕ26

ϕ27

ϕ30 0.3293 0.3232 0.3096 0.3219 0.2300ϕ31 0.2778 0.3589 0.3213 0.3565 0.2941 0.3259 0.2070ϕ35 0.4661 0.4010 0.2519 0.3856 0.3854 0.4635 0.4048 0.2893ϕ36 0.2106 0.2172 0.3003ϕ37 0.2124 0.2023 0.2255 0.2123ϕ38

ϕ39 0.2029 0.2264f40 0.4239f41

f42 0.2725


f43

f50 0.4095 0.3640f52 0.2129f53 0.2723f54

f55 0.2227f56

f59

Sum

mat

ion

Valu

es .2856 0.9622 0.5361 2.2112 1.2047 0.3096 1.1714 1.2824 0.9571 1.5924

N.B.: Orbitals having eigenvector values above 0.20 have only been considered.

The first fourteen molecular orbitals, i.e. ϕ15-

16, ϕ18-21, ϕ23-27, ϕ30-31 and ϕ35 have contributions

from 3d orbitals of the metal and the remaining

fifteen molecular orbitals i.e. ϕ36-43, ϕ50-52, ϕ52-56

and ϕ59 have contribution from vacant 4s, 4px,

4py and 4pz orbitals of the metal in Table 3. To

examine the extent of involvement of 3d, 4s

and 4p orbitals in the formation of molecular

orbitals, the values of coefficient of each orbital

have been added to see the total involvement in

all the 29 molecular orbitals. The summation

values are placed at the bottom of the Table 3.

Figure 2. Trend of summation value of eigenvector of nickel orbital

0

1

2

3

4

5

6

4py 4pz 4px 4s 3dyz 3dxz 3dx2-y2 3dxz 3dz2

nickel orbital

summation value of eigenvector of nickel orbital

The graphical representation of involvement

of 3d, 4s and 4p orbitals of nickel are shown in

Figure 2 and the total involvement of orbitals

of 2pz carbon atoms of both the C5H5¯ and their


summation values are placed at the bottom of

the Table 4 and graphical representation of

the involvement of 2pz of ten carbon atom is

showing in Figure 3. Figure 2 clearly indicated

that 4py orbital has the maximum involvement

out of 4s and 4p orbitals and 3dyz orbital

has the maximum involvement from the 3d

orbitals. These sequences from the two series

are:

2 2 2

4 4 4 4 ,

3 3 3 3 3

y z xp p p s

dyz dxz dx y dxy dz

>> >

> > - > >

Figure 3 clearly indicates that eigenvector

value of 2pz orbital 4C has the maximum

involvement out of ten carbon atoms of both

the C5H5¯.

Figure 3. Trend of summation value of eigenvector of carbon orbital.

0

0.5

1

1.5

2

2.5

4C 10C 1C 8C 5C 7C 2C 9C 3C 6C

summation values of eigenvector values of 2pz orbital of carbon

1- Eigenvalues

The eigenvalues of 59 molecular orbitals of

nickelocene are listed in Table 2, out of which

we shall discuss only 29 molecular orbitals in

Table 3 and Table 4. The first fourteen MOs

are formed by various 3d orbitals and 2pz

orbitals of C5H5¯ ion. These orbitals are the

most molecular orbitals between nickel and

2pz orbitals of C5H5¯. They have their energies

in the range -0.5462 to -0.2296 eV. The

contribution of 3d nickel and 2pz of carbon in

the formation of ϕ15-ϕ35 MOs is described as

below:

( ) ( )15 49 48 3 , 3 .Ni dyz Ni dxzf c c- - -

( )16 48 3 .Ni dxzf c- -

( )18 47 3 .Ni dxyf c- -

( )19 47 3 .Ni dxyf c- -

( )2 220 45 3 - y .Ni dxf c- -

( ) ( )2 221 45 163 - y , 4 2 .zNi dx C pf c c- - -

( ) ( )2 223 45 163 - y , 4 2 .zNi dx C pf c c- - -

( ) ( ) ( )24 48 47 493 , 3 , 3 .Ni dxz Ni dxy Ni dyzf c c c- - - -

( ) ( ) ( )( ) ( )

2 2 225 45 46

48 40

3 , 3 , 3 , 49

3 , 10 2 . z

Ni dx y Ni dz Ni dyz

Ni dxz C p

f c c c

c c

- - - - -

- -

( ) ( )226 46 49 3 , 3 .Ni dz Ni dyzf c c- - -

( ) ( )27 47 49 3 , 3 .Ni dxy Ni dyzf c c- - -

( ) ( ) ( )( ) ( ) ( )( ) ( )2

30 48 49 4

12 32 24

46 40

3 , 3 , 1 2 ,

3 2 , 8 2 , 6 2 ,

3 , 10 2 .

z

z z z

z

Ni dxz Ni dyz C p

C p C p C p

Ni dz C p

f c c c

c c c

c c

- - - -

- - -

- -


( ) ( ) ( )( ) ( ) ( )( ) ( ) ( )

31 48 49 8

28 36 20

32 4 40

3 , 3 , 2 2 ,

7 2 , 9 2 , 5 2 ,

8 2 , 1 2 , 10 2 .

z

z z z

z z z

Ni dxz Ni dyz C p

C p C p C p

C p C p C p

f c c c

c c c

c c c

- - - -

- - -

- - -

( ) ( ) ( )( ) ( ) ( )( ) ( ) ( )2 2

35 4 32 36

8 20 28

40 45 16

1 2 , 8 2 , 9 2 ,

2 2 , 5 2 , 7 2 ,

10 2 , 3 , 4 2 .

z z z

z z z

z z

C p C p C p

C p C p C p

C p Ni dx y C p

f c c c

c c c

c c c

- - - -

- - -

- - - -

The next fifteen molecular orbitals are formed

by interaction of 4s, 4px, 4py and 4pz orbitals of

metal and 2pz orbitals of carbon. These MOs

are comparatively less stable and have their

energies between 0.0713 and 4.2942 eV. The

contribution of various atomic orbitals in the

formation of molecular orbitals is presented

below.

( ) ( ) ( )( ) ( )

36 43 42 44

28 16

4 , 4 , 4 ,

7 2 , 4 2 .

y x z

z z

Ni p Ni p Ni p

C p C p

f c c c

c c

- - - -

- -

( ) ( ) ( )( ) ( ) ( )

( )

37 41 42 43

20 4 28

8

4 , 4 , 4 ,

5 2 , 1 2 , 7 2 ,

2 2 .

x y

z z z

z

Ni s Ni p Ni p

C p C p C p

C p

f c c c

c c c

c

- - - -

- - -

-

( ) ( ) ( )38 41 43 424 , 4 , 4 .y xNi s Ni p Ni pf c c c- - - -

( ) ( ) ( )( ) ( )

39 42 43 44

36 32

4 , 4 , 4 ,

9 2 , 8 2 .

x y z

z z

Ni p Ni p Ni p

C p C p

f c c c

c c

- - - -

- -

( ) ( ) ( )( )

40 16 43 41

42

4 2 , 4 , 4 ,

4 .

z y

x

C p Ni p Ni s

Ni p

f c c c

c

- - - -

-

( )41 44 4 .zNi pf c- -

( ) ( ) ( )42 42 43 16 4 , 4 , 4 2 .x y zNi p Ni p C pf c c c- - - -

( ) ( )43 43 42 4 , 4 .y xNi p Ni pf c c- - -

( ) ( ) ( )50 41 16 40 4 , 4 4 , 10 2 .z zNi s C p C pf c c c- - - -

( ) ( ) ( )( )

52 40 42 43

12

10 2 , 4 , 4 ,

3 2 .

z x y

z

C p Ni p Ni p

C p

f c c c

c

- - - -

-

( ) ( ) ( )53 42 20 444 , 5 2 , 4 .x z zNi p C p Ni pf c c c- - - -

( ) ( ) ( )54 41 43 424 , 4 , 4 .y xNi s Ni p Ni pf c c c- - - -

( ) ( )55 44 164 , 4 2 .z zNi p C pf c c- - -

( )56 41 4 .Ni sf c- -

( ) ( ) ( )59 44 43 424 , 4 , 4 .z y xNi p Ni p Ni pf c c c- - - -


Figure 4: Energy level diagram of nickelocene

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

15 16 18 19 20 21 23 24 25 26 27 30 31 35 36 37 38 39 40 41 42 43 50 52 53 54 55 56 59

ener

gyva

lues

(eV

)

Molecular orbital

The energy level diagram has been draw

for representing MOs and their eigenvalues

which is shown in Figure 4. In this Figure the

stable MOs (ϕ15-ϕ35) i.e. 3d orbitals and less

stable MOs (ϕ36-ϕ59) i.e. 4s and 4p orbitals of

nickelocene. The energy ranges of 3d orbitals

are -0.5462 to -0.2296 eV whereas the energy

ranges of 4s, 4p orbitals are 0.0713 to 4.2942 eV.

2- Population analysis

The contribution of electrons in each occupied

MO is calculated by using the population

analysis method, introduced by Mulliken. This

method apportions the electrons of n-electron

molecular into net population nr in the basis

function χr. Let there be ni electrons in the

MO ϕi (ni =0,1,2) and let nr,i symbolize the

contribution of electrons in the MO ϕi to the

net population in χr we have

(1)

where, cri is the coefficient of atomic orbitals

for ith MO (r=1-30) . Equation 1, has been

solved for 59 electrons of 30 molecular orbitals

in nickelocene, each MO has two electrons.

The coefficient [19-23] of atomic orbitals i.e.

cri is the eigenvector value. Since our interest

is only in MO-15-30, we have tabulated the

results of these MOs in tables 5-20.

Table 5: Contribution of electrons in MO-15.

c Atomic orbital Eigenvector( ric ) No. of electrons ( in ) ,2

r i i rin = n c

15 4C – 2py 0.1684 2 0.05671712118 5C – 2px 0.1912 2 0.0731148827 7C – 2py 0.1618 2 0.0523584835 9C – 2py 0.1507 2 0.04542098


36 9C – 2pz 0.1678 2 0.0563136838 10C – 2px 0.1815 2 0.0658845048 11Ni – 3dxz 0.3209 2 0.205936249 11Ni – 3dyz 0.3365 2 0.226464554 16H – 1s 0.2039 2 0.0831504258 20H – 1s 0.1952 2 0.07620608



r i i rin = n c

3 1C – 2py 0.1963 2 0.077067387 2C – 2py 0.1585 2 0.0502445010 3C – 2px 0.1800 2 0.0648000011 3C – 2py 0.1626 2 0.0528775222 6C – 2px 0.1654 2 0.0547143223 6C – 2py 0.1656 2 0.0548467226 7C – 2px 0.1675 2 0.0561125030 8C – 2px 0.2485 2 0.1235045048 11Ni – 3dxz 0.2294 2 0.1052487249 11Ni – 3dyz 0.1991 2 0.0792816250 12H – 1s 0.2143 2 0.0918489852 14H – 1s 0.2114 2 0.0893799255 17H – 1s 0.1998 2 0.0798400857 19H – 1s 0.2357 2 0.11110898


χ Atomic orbital Eigenvector( ric ) No. of electrons ( in ) ,2

r i i rin = n c

4 1C – 2pz 0.2524 2 0.127411528 2C – 2pz 0.2648 2 0.1402380812 3C – 2pz 0.2359 2 0.1112976216 4C – 2pz 0.1694 2 0.0573927220 5C – 2pz 0.2100 2 0.0882000024 6C – 2pz 0.2578 2 0.1329216828 7C – 2pz 0.2709 2 0.1467736232 8C – 2pz 0.2389 2 0.1141464236 9C – 2pz 0.2224 2 0.0989235240 10C – 2pz 0.1972 2 0.07777568




r i i rin = n c

2 1C – 2px 0.1613 2 0.052035386 2C – 2px 0.2257 2 0.101880987 2C – 2py 0.1658 2 0.0549792811 3C – 2py 0.1614 2 0.0520999227 7C – 2py 0.2370 2 0.1123380031 8C – 2py 0.1627 2 0.0529425847 11Ni – 3dxy 0.3605 2 0.259920551 13H – 1s 0.2753 2 0.1515801856 18H – 1s 0.2647 2 0.14013218



r i i rin = n c

2 1C – 2px 0.1660 2 0.055120003 1C – 2py 0.2338 2 0.1093248815 4C – 2py 0.1573 2 0.0494865816 4C – 2pz 0.1590 2 0.0505620019 5C – 2py 0.3017 2 0.1820457830 8C – 2px 0.1644 2 0.0540547234 9C – 2px 0.2715 2 0.1474245038 10C – 2px 0.1898 2 0.0720480847 11Ni – 3dxy 0.3128 2 0.1956876850 12H – 1s 0.1716 2 0.0938931253 15H – 1s 0.1817 2 0.0660297859 21H – 1s 0.1818 2 0.06610248



r i i rin = n c

7 2C – 2py 0.1648 2 0.0543180811 3C – 2py 0.1679 2 0.0563808214 4C – 2px 0.1936 2 0.0749619222 6C – 2px 0.2181 2 0.0951352223 6C – 2py 0.2016 2 0.0812851226 7C – 2px 0.2357 2 0.1111089839 10C – 2py 0.2501 2 0.1251000245 11Ni – 3dx2-y2 0.5297 2 0.5611461853 15H – 1s 0.1782 2 0.0635104859 21H – 1s 0.1675 2 0.0561125




r i i rin = n c

2 1C – 2px 0.1835 2 0.06734453 1C – 2py 0.1652 2 0.054582087 2C – 2py 0.1694 2 0.0573927216 4C – 2pz 0.2019 2 0.0815272219 5C – 2py 0.2562 2 0.1312768830 8C – 2px 0.1765 2 0.0623045031 8C – 2py 0.1712 2 0.0586188834 9C – 2px 0.3283 2 0.2155617838 10C – 2px 0.1622 2 0.0526176840 10C – 2pz 0.1986 2 0.0788839245 11Ni – 3dx2-y2 0.3029 2 0.18349682



r i i rin = n c

2 1C – 2px 0.1975 2 0.07801256 2C – 2px 0.1940 2 0.07527207 2C – 2py 0.2670 2 0.142578011 3C – 2py 0.2285 2 0.104424514 4C – 2px 0.2041 2 0.083313622 6C – 2px 0.2059 2 0.084789626 7C – 2px 0.2529 2 0.127916827 7C – 2py 0.2025 2 0.082012531 8C – 2py 0.2114 2 0.089379950 12H – 1s 0.2083 2 0.0867777



r i i rin = n c

2 1C – 2px 0.1878 2 0.070537686 2C – 2px 0.1708 2 0.0583452810 3C – 2px 0.1855 2 0.0688205014 4C – 2px 0.1622 2 0.0526176815 4C – 2pz 0.2182 2 0.0952224822 6C – 2px 0.1654 2 0.0547143223 6C – 2py 0.1538 2 0.0473088828 7C – 2pz 0.1815 2 0.0658845031 8C – 2py 0.1784 2 0.0636531235 9C – 2py 0.1866 2 0.06963912


39 10C – 2py 0.1592 2 0.0506892845 11Ni – 3dx2-y2 0.4179 2 0.3492808249 11Ni – 3dyz 0.1838 2 0.0675648851 13H – 1s 0.1668 2 0.0556444856 18H – 1s 0.1937 2 0.07503938



r i i rin = n c

3 1C – 2py 0.1820 2 0.066248004 1C – 2pz 0.1568 2 0.0491724818 5C – 2px 0.1794 2 0.0643687220 5C – 2pz 0.1692 2 0.0572572832 8C – 2pz 0.1544 2 0.0476787240 10C – 2pz 0.1707 2 0.0582769847 11Ni – 3dxy 0.3849 2 0.2962960248 11Ni – 3dxz 0.4986 2 0.4972039249 11Ni – 3dyz 0.2011 2 0.08088242



r i i rin = n c

2 1C – 2px 0.1650 2 0.054450006 2C – 2px 0.1564 2 0.0489219212 3C – 2pz 0.1641 2 0.0538576231 8C – 2py 0.1813 2 0.0657393834 9C – 2px 0.1670 2 0.0557780040 10C – 2pz 0.2018 2 0.0814464845 11Ni – 3dx2-y2 0.5232 2 0.5474764846 11Ni – 3dz2 0.3369 2 0.2270032248 11Ni – 3dxz 0.2396 2 0.1148163249 11Ni – 3dyz 0.2782 2 0.15479048



r i i rin = n c

19 5C – 2py 0.1617 2 0.0522937846 11Ni – 3dz2 0.7408 2 1.0975692849 11Ni – 3dyz 0.4949 2 0.48985202



r i i rin = n c

10 3C – 2px 0.2142 2 0.09176328


14 4C – 2px 0.2444 2 0.1194627223 6C – 2py 0.1830 2 0.0669780024 6C – 2pz 0.1666 2 0.0555111231 8C – 2py 0.1508 2 0.0454812839 10C – 2py 0.2367 2 0.1120537847 11Ni – 3dxy 0.6697 2 0.8969961849 11Ni – 3dyz 0.2358 2 0.11120328



r i i rin = n c

4 1C – 2pz 0.2818 2 0.1588224812 3C – 2pz 0.3050 2 0.1860500019 5C – 2py 0.1790 2 0.0640820020 5C – 2pz 0.2252 2 0.1014300824 6C – 2pz 0.4088 2 0.3342348828 7C – 2pz 0.2304 2 0.1061683234 9C – 2px 0.1649 2 0.0543840235 9C – 2py 0.1981 2 0.0784872236 9C – 2pz 0.3089 2 0.1908384245 11Ni – 3dx2-y2 0.1702 2 0.05793608



r i i rin = n c

8 2C – 2pz 0.4179 2 0.3492808212 3C – 2pz 0.2037 2 0.0829873815 4C – 2py 0.2099 2 0.0881160216 4C – 2pz 0.2561 2 0.1311744220 5C – 2pz 0.2707 2 0.1465569828 7C – 2pz 0.3600 2 0.2592000036 9C – 2pz 0.2006 2 0.0804807238 10C – 2px 0.1600 2 0.0512000040 10C – 2pz 0.3209 2 0.2059536246 11Ni – 3dz2 0.2012 2 0.08096288



r i i rin = n c

4 1C – 2pz 0.3293 2 0.2168769812 3C – 2pz 0.3232 2 0.2089164816 4C – 2pz 0.1812 2 0.0656668820 5C – 2pz 0.1505 2 0.04530050


24 6C – 2pz 0.3096 2 0.1917043231 8C – 2py 0.1593 2 0.0507529832 8C – 2pz 0.3219 2 0.2072392236 9C – 2pz 0.1864 2 0.0694899240 10C – 2pz 0.2300 2 0.1058000046 11Ni – 3dz2 0.2979 2 0.1774888247 11Ni – 3dxy 0.1819 2 0.0661752248 11Ni – 3dxz 0.4786 2 0.4581159249 11Ni – 3dyz 0.3521 2 0.24794882

The results of solution of equation-1 for

MOs of 15-30 clearly indicates that main

contribution of electrons in MO-15 is from 2px

orbitals of 5C, 10C and from nickel it is from

3dyz, 3dxz. In MO-16 it is from 2px orbitals of

5C, 3C and 2py of 1C and 3dyz, 3dxz of nickel.

Briefly the contribution of electrons in other

MOs can be presented as below:

MO- 17 7C – 2pz, 2C – 2pz, 6C – 2pz, 1C – 2pz, 3C – 2pz, 8C – 2pz, 3C – 2pz,9C – 2pz, 5C – 2pz.

MO- 18 7C – 2py, 2C – 2px, Ni – 3dxy.

MO- 19 5C – 2py, 9C – 2px, 1C – 2py, 10C – 2px, Ni – 3dxy.

MO- 20 10C – 2py, 7C – 2px, 6C – 2px, 6C – 2py, Ni – 3dx2-y2.

MO- 21 9C – 2px, 5C – 2py, 4C – 2pz, 1C – 2pz, Ni – 3dx2-y2.

MO- 22 2C – 2py, 7C – 2px, 3C – 2py, 8C – 2py, 6C – 2px, 4C – 2px, 7C – 2py,1C – 2px, 2C – 2px.

MO- 23 4C – 2pz, 1C – 2px, 9C – 2py, 3C – 2px, 7C – 2pz, Ni – 3dx2-y2, 3dyz.

MO- 24 1C – 2py, 5C – 2px, 10C – 2pz, Ni – 3dxz, 3dxy.

MO- 25 10C – 2pz, 8C – 2py, Ni – 3dx2-y2, 3dz2, 3dyz, 3dxz.

MO- 26 Ni – 3dz2, 3dyz.

MO- 27 4C – 2px, 10C – 2py, 3C – 2px, 6C – 2py, Ni – 3dxy, 3dyz.

MO- 28 6C – 2pz, 9C – 2pz, 3C – 2pz, 1C – 2pz, 7C – 2pz, 5C – 2pz, 9C – 2pz,Ni – 3dx2-y2.

MO- 29 2C – 2pz, 7C – 2pz, 10C – 2pz, 5C – 2pz, 4C – 2pz, 4C – 2py, 3C – 2pz, 9C – 2pz, Ni – 3dz2.

MO- 30 1C – 2pz, 3C – 2pz, 8C – 2pz, 6C – 2pz, 10C – 2pz, 9C – 2pz, 4C – 2pz, Ni – 3dxz, 3dyz, 3dz2, 3dxy.

ConclusionThe nine atomic orbitals which are involved in bonding are one 4s, three 4p and five 3d. The coefficient of eigenvector are in range 1.3756 – 4.9416 eV, the lowest value of 3dz2 and

highest of 4py. The involvements of d orbitals are in MOs 15 – 35 and of 4s and 4p in the MOs 36 – 59. The MOs involving d orbital have eigenvalues in the range 0.5462 – 0.2296 eV, i.e. in bonding range whereas 4s and 4p orbitals


are in range 0.0713 – 4.2942 eV which anti bonding range. The 2pz orbitals of ten carbon atoms of two C5H5¯ are involved in bonding with nine nickel orbitals. The coefficient of eigenvector of 2pz of carbon is in the range 0.3096 – 2.2112 eV. The major involvements are in molecular orbitals 30 – 55.

AcknowledgementsThis paper is dedicated to my mother Smt Esqual Khan. I am thankful to Dr. R. N. Verma, Department of Physics, K. S. Saket Post Graduate College, Ayodhya-Faizabad, U.P., INDIA. for valuable suggestions.

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