synthesis, x-ray structural and vibrational analysis using...

CHAPTER III

SYNTHESIS, X-RAY STRUCTURAL AND VIBRATIONAL

ANALYSIS USING DFT STUDY OF 4-METHYL-N-

(NAPHTHALENE-1-YL)BENZENE SULFONAMIDE

3.1 INTRODUCTION

Sulfonamides, an important class of pharmaceutical compounds exhibit a

wide spectrum of biological activities [1-3]. Over 30 drugs containing this

functionality are inclinical use, including, antibacterials, diuretics, anticonvulsants,

hypoglycemics and HIV protease inhibitors[4 ]. More recently, sulfonamides have

been found to be potent cysteine protease inhibitors, which could possibly extend

their therapeutic applications to include conditions such as Alzheimer’s disease,

arthritis and cancer [5-6]. The vast majority of sulfonamides are prepared from the

reaction of a sulfonyl chloride with ammonia or primary or secondary amines or

via related transformations [7,8].

The structure of naphthalene is benzene like, having two-six membered

rings fused together. Naphthalene resembles benzene in many of its reaction

although it is somewhat less aromatic but more reactive than benzene. Naphthalene

and its derivatives are used as a parent compound to make many drugs, a precursor

for the synthesis of plastics and dyes, also used synthetic resins, in dye stuffs,

coatings and celluloid [9-11]. Especially, naphthalene was studied because of its

technological applications in a vast amount of industrial process [9].

Extensive experimental and theoretical investigations have focused

on elucidating the structure and normal vibrations of naphthalene and

its derivatives. Doroto et al [12] reported experimental and theoretical

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76

examination of intramolecular motions in N-(4–X–naphthalene–1–yl)–N–ethyl–4-

methylbenzenesulfonamides. Shoba et al[13] reported FT-IR and FT-Raman

vibrational analysis, ab initio HF and DFT simulations of isocyanic acid

1-naphthyl ester.

Srivastava has investigated the infrared and Raman spectrum of the

condensed and liquid phase naphthalene and its cation [14]. Extensive recent

studies of vibrational spectra of substituted naphthalene compounds have assigned

[13-16] complete vibrational mode and frequency analyses. Arivazhagan et al [10]

studied the molecular structure and vibrational spectra of 1,5-dinitronaphthalene.

The vibrational spectra and normal coordinate analysis of plant growth regulator

1-naphthalene acetamide was investigated by Ravikumar et al [15]. Kavitha et al

[16] have studied the molecular structure, vibrational frequencies and NBO

analysis of naphthalene acetic acid. Govindarajan et al. [11] investigated

vibrational analysis of 1-Methoxynaphthalene by experimental techniques (FT-IR

and FT-Raman) and DFT methods. The IR and Raman spectra of the 2,6-, 2,7-, and

2,3-diisopropylnaphthalene molecules were calculated at the B3PW91/6-311G*

level and interpreted in terms of the potential energy distribution (PED) analysis by

Jamroz et al [17]. The vibrational properties of 1-naphthaldehyde have been

investigated by FT IR and FT-Raman spectroscopies and quantum chemical

calculations which were performed on the basis of DFT(B3LYP) method by

Krishnakumar et al [18]. Green and Harrison investigated the vibrational spectra of

monosubtituted naphthalenes [19].

Pimental et al [20] reported a spectroscopic study of naphthalene with

vibrational analysis. Polarized spectra of single crystals were taken and the infrared

dichroic effects were interpreted by an oriented-gas model.


77

Sellers et al [21] reported theoretical prediction of vibrational spectra, force

field, refined geometry and reassignment of the vibrational spectrum of

naphthalene. The complete haromonic force field of naphthalene has been

calculated by ab initio at the 4-21 HF level.

A combined experimental and theoretical study on molecular and

vibrational structure of 2,3-dimethylnaphthalene has been presented by Prabhu

et al [22]. The FTIR and FT-Raman spectra were recorded in the region

4000-100 cm-1. The optimized geometries were calculated by HF and DFT

methods. The harmonic frequencies, IR intensity and Raman activities were

evaluated. From the vibrational analysis of the study it was concluded that the

substitution of methyl group in the naphthalene ring distorts the geometry and the

planarity of the molecule to some extent.

Several studies have been conducted on the vibrational spectra,electron

exchange, structural stability, lattice vibrations, antiresonance of naphthalene using

normal co-ordinate analysis and resonance Raman spectral analysis [23–35]. Das

et al. [36] studied the infrared spectra of dimethylnaphthalenes in the gas phase.

Librando and Alparone [37-39] investigated methyl naphthalene isomers on

quantum mechanical approach and the electronic polarizability of

dimethylnaphthalenes. Because of their spectroscopic properties and chemical

significance in particular, naphthalene and its derivatives have been studied

extensively by spectroscopic techniques and theoretical methods.

Since naphthalene and its derivatives have wide applications in the

biological, pharmaceutical and industrial processes 4-methyl-N-(naphthalene-1-yl)

benzene sulfonamide (abbreviated 4MNBS) has been taken for the present study.

And also, to the best of our knowledge, neither crystal structure nor DFT


78

calculation of 4MNBS has been reported. Therefore, synthesis, crystal structure,

spectral studies, NBO analysis, atomic charges, Homo-Lumo analysis and

Molecular electro static potential of 4MNBS are reported here. Triclinic structure

of the title compound has been deposited at the Cambridge Crystallographic Data

Center with the deposition number CCDC 765626 for [4MNBS]. The geometrical

parameters, fundamental frequencies in the ground state have been calculated by

using the DFT (B3LYP) method with 6-31G (d,p) basis set, and compared with

experimental data. Recently, computational methods based on density functional

theory are becoming widely used. These methods predict relatively accurate

molecular structure and vibrational spectra with moderate computational effort. In

particular, for polyatomic molecules (typically normal modes exceeding 50) the

DFT methods lead to the prediction of more accurate molecular structure and

vibrational wavenumbers than the conventional ab initio restricted Hartree-Fock

(RHF) and Moller-plesset second order perturbation theory (MP2) calculations.

3.2 SYNTHESIS

1-naphthyl amine (7.15gm), Diethylamine (4ml) were dissolved in acetone

(8 ml). To this solution, 4-methyl benzene sulfonyl chloride (9.53gm) in acetone

(12.5ml) was added in drops with continuous stirring of the solution. The resulting

solution was allowed to evaporate. The residue was washed several times with

water and then with petroleum ether. The crude product of the title compound was

recrystallized from ethanol. After one week colourless crystals suitable for x-ray

diffraction studies were obtained. The scheme of the synthesis is shown in

Figure 3.1.


Figure 3.1 Pathway of the synthesis of the title compound.

CH3

SO2Cl

NH2

+

NHSO2 CH3

ACETONE

︵C2H5 ︶2NH


79

3.3 COMPUTATIONAL DETAILS

The entire calculations conducted in the present work were performed at

B3LYP levels included in the Gaussian 03W package [33] program together with

6-31G (d,p) basis set function of the density functional theory (DFT) utilizing

gradient geometry optimization [34]. Initial geometry generated from standard

geometrical parameters was minimized without any constraint in the potential

energy surface at Hartree-Focklevel, adopting the standard 6-31G (d,p) basis set.

This geometry was reoptimized again at B3LYP level, using basis set 6-31G (d, p)

for better description. The optimized structural parameters were used in the

vibrational frequency calculations at the DFT levels to characterize all stationary

points as minima. At the optimized structure of the examined species, no

imaginary frequency modes were obtained proving that a true minimum on the

potential energy surface was found. We have utilized the gradient corrected density

functional theory[35] with the three parameter hybrid functional (B3) [36] for the

exchange part and the Lee- Yang –Parr (LYP) correlation function [37], accepted

as a cost effective approach for the computation of molecular structure, vibrational

frequencies and energies of optimized structures. By combining the results of the

Gauss view program [38] with symmetry considerations, vibrational frequency

assignments were made with a high degree of accuracy. The harmonic Vibrational

frequencies were calculated at the same level of theory for the optimized structures

and obtained frequencies were scaled by 0.961. 1H and 13C chemical shifts were

calculated with GIAO method using corresponding TMS shielding calculated at

the B3LYP (6-31G (d,p)) level. The natural bonding orbitals (NBO) calculations

[39] were performed using NBO 3.1 program as implemented in the Gaussian 03W

[33] package at the DFT/B3LYP/6-31G(d,p) level in order to understand various

second order interactions between the filled orbitals of one subsystem and vacant


80

orbitals of another subsystem, which is a measure of the intramolecular

delocalization or hyper conjugation. HOMO and LUMO analysis have been used

to elucidate the information regarding charge transfer within the molecule.

Molecular electrostatic potential analysis has been used to find the reactive sites of

the compound.

3.4 SINGLE CRYSTAL X-RAY DIFFRACTION ANALYSIS

3.4.1 Crystal Structure Determination

A crystal with dimensions of 0.28 x 0.22 x 0.18 mm was used for

collection of intensity data on a “Bruker Apex II CCD” area detector

diffractometer with graphite monochromated MOKα radiation (0.71073), ω scan

technique. The programs used to solve and refine the structure were SHELXS-97,

SHELXL97 and PLATON [40-41]. The refinement was carried out by using the

Full matrix least square on F2. All non hydrogen atoms were refined

anisotropically. All hydrogen atoms were geometrically fixed and refined with

isotropic thermal parameters. Crystallographic details are shown in Table 3.1,

whereas selected bond lengths and bond angles are shown in Table 3.2.

3.4.2 Crystal Structure analysis

An ORTEP [49] view of the title compound is shown in Figure 3.2. In the

crystal structure of the title compound (C17H15NO2S), the dihedral angle between

the mean planes of the tolyl and naphthyl ring is 66.6(3)⁰. This shows their non

coplanar conformation. This is in contrast with the near coplanar conformation

reported for the crystal structure of 4-[(2-hydroxy-benzylidene)-amino]-N-(5-

methyl-isoxazol-3-yl)-benzenesulfonamide [50]. All the C-C and C-O bond


Table 3.1 Crystal data and structure refinement parameters for 4MNBS

Empirical formula C17 H15 N O2 S Formula weight 297.36 Temperature 298(2) K Wavelength 0.71073 Å Crystal system, space group Triclinic, p-1 Unit cell dimension a = 10.3873(7)Å α =75.735(3)⁰ b = 10.4090(7)Å ß=70.737(3)⁰ c = 15.7084(10)Å ᵞ= 68.120(3)⁰ Volume (Å3) 1472.98(17) Z, Calculated density 4, 1.341 Mg/m3

Absorption coefficient 0.223 mm-1

F(000) 624 Crystal size 0.28 x 0.22 x 0.18 (mm3) Theta range for data collection 1.39 to 28.63⁰ Limiting indices -13<=h<=13, -14<=k<=12, -20<=l<=16 Reflections collected / unique 18793 / 6687 [R(int) = 0.0565] Completeness to theta = 25.00 96.3 % Max. and min. transmission 0.9609 and 0.9402 Refinement method Full-matrix least-squares on F2

Data / restraints / parameters 6687 / 0 / 390 Goodness-of-fit on F^2 0.933 Final R indices [I>2sigma(I)] R1 = 0.0534, wR2 = 0.1057 R indices (all data) R1 = 0.1675, wR2 = 0.1460 Extinction coefficient 0.0106(15) Largest diff. peak and hole 0.210 and -0.253 e.Å-3


Table 3.2 Selected molecular structure parameters of 4MNBS Parameters Experimental B3LYP6‐31G(d,p)

Bond Lengths (Å) C1‐C2 1.372(4) 1.397 C1‐C6 1.376(4) 1.394 C3‐C4 1.369 1.401 C5‐C6 1.374 1.391 C2‐C3 1.384 1.394 C4‐C7 1.507(4) 1.509 C1‐S1 1.747(3) 1.789 S1‐O1 1.435(2) 1.467 S1‐O2 1.427(2) 1.467 S1‐N1 1.626 1.647 N1‐H1 0.77(3) 1.018 C7‐H(7A) 0.96 1.093 C8‐N1 1.419(4) 1.44 C8‐C17 1.432(4) 1.421 C8‐C9 1.359(4) 1.381 C10‐C11 1.35(4) 1.375 C13‐C14 1.348(5) 1.375 C9‐C10 1.394(4) 1.376 C8‐C17 1.432(4) 1.43 C11‐C12 1.411(4) 1.415 C12‐C13 1.417(4) 1.421 C12‐C17 1.423(4) 1.421 C14‐C15 1.391(4) 1.412 C9‐H9 0.93 1.084 Bond angles(⁰) C2‐C1‐S1 120.8(2) 119.6 C6‐C1‐S1 119.0(2) 119.3 C1‐C2‐C3 119.3(3) 120.2 C1‐C2‐H2 120.3 120.4 C3‐C2‐H2 120.3 121.1 C3‐C4‐C5 117.5(3) 118.5 O2‐S1‐N1 108.88(15) 109.5 O1‐S1‐C1 108.05(13) 109.1 O2‐S1‐O1 118.86(12) 121.2


O1‐S1‐N1 104.77(14) 105.5 N1‐S1‐C1 107.77(14) 108.6 C8‐N1‐S1 125.3(2) 124.1 C4‐C7‐H7(A) 109.5 111.5 C4‐C3‐C7 121.5(4) 120.6 C17‐C8‐N1 120.3(3) 118.12 C9‐C8‐C17 120(3) 120.61 C9‐C8‐N1 119.6(3) 121.24 C8‐N1‐H(1N) 115(2) 114.8


Figure (3.2a) An ORTEP drawing of 4MNBS, with the atom numbering Scheme. Displacement ellipsoids are drawn at the 30% Probability level.


81

lengths are comparable to the reported mean values of Caro-Caro =1.380Å and C-C

=1.530Å [51].

The atoms around the ‘S’ atom in the title compound exhibit a slightly

distorted tetrahedral configuration with the largest angle O (2)-S (1)-O (1) of

118.86(12) °, but it conforms to the non-tetrahedral arrangement commonly

observed in sulfonamides [52-58]. The bond angle N1-S1-C1 of 107.70 (14) ° is

correspondingly smaller than the tetrahedral value of 109° [59]. The S1-C1

distance of 1.7561(13) Å is normal single bond value and agrees well with those

observed in other sulfonamides [60-61]. The two torsion angles τ1(C-C-S-N) and

τ2(C-S-N-C) defining the conformation of the sulfonamide group were reported to

lie in the range 70-120⁰ and 60-90⁰ respectively [62]. In the present crystal

structure, the torsion angles τ1 (C6-C1-S1-N1) and τ2 (C8-N1-S1-C1) are

70.3 (3)⁰ and 66.6(3)⁰ respectively. The position of the methyl group C7 is defined

by the torsion angles τ1 (C7-C4-C5-C6) and τ2 (C2-C3-C4-C7) are -178.4(3) and

178.2 (3)° respectively. In each molecule the tolyl and naphthyl rings are nearly

perpendicular to each other. The tolyl ring is slightly twisted towards the naphthyl

ring which can be attributed to the compression of the tolyl ring as shown by the

C1-S1-N1 bond angle.

3.4.3 Hydrogen Bonding and Crystal Packing

The crystal packing is stabilized by intermolecular N-H…O interaction.

The crystal packing of molecules of the title compound viewed down the ‘a’ axis is

shown in Fig. 3.3. Atom N1 in the molecule at (x, y, z) donates one proton to atom

O1 in the molecule at (-x+1,-Y+1, -Z+2), similarly atom N1 in the molecule at

(-x+1,-Y+1, -Z+2) donates one proton to atom O1 in the molecule at (x, y, z). This


82

intermolecular hydrogen bond forms a R2 (6) ring motif. Hydrogen bonds for

4MNBS is shown in Table 3.3.

3.4.4 Geometrical Structure

The optimized structure parameters of the title compound were calculated

by DFT –B3LYP levels with the 6-31G (d, p) basis set. The selected bond lengths,

bond angles and torsion angles are compared with the experimental data of the title

compound (Table 3.2). All calculated geometrical parameters obtained at the DFT

level of theory are in good agreement with the experimental structural parameters.

No X-ray crystallographic data of the title compound have yet been

reported to best of our knowledge. However, the theoretical results (B3LYP)

obtained are almost comparable with the reported structural parameters of similar

derivatives. Unlike benzene, the carbon –carbon bands for naphthalene derivatives

are not of the same length [63, 64]. For the title compound, the bonds C8–C9,

C10–C11, C13–C14, C9–C10, and C14–C15 are 1.381, 1.3751, 1.3754, 1.3765,

1.412 Å in length, whereas the other C–C bonds lie in the range of 1.4158–1.4302

Å. This difference occurs due to that electronegative substituent (NH) on

naphthalene ring trend to shorten the C–C bonds adjacent to the substituent. The

same trend is observed for XRD data. In toluene ring, all the carbon- carbon bond

lengths are calculated in the range of 1.395-1.401 Å for B3LYP and observed in

the range of 1.369-1.378 Å for XRD data.

Loughrey et al. [65] reported the bond lengths, S31–O32 = 1.4337, S31–

O33 = 1.4256, S31–N34 = 1.6051, S31–C28 = 1.7737 and C21–N20 = 1.4212 Å,

whereas the corresponding values for the title compound are, 1.467, 1.467, 1.647,

1.789, and 1.44 Å . The above said bond lengths, S1-O1, S1-O2, S1-N1, S1-C1and


Table 3.3 Hydrogen bond geoeometry(Å) D‐H‐A D‐H H‐A D…A <(DHA) N1‐H1…O1 0.77(3) 2.28(3) 3.018(4) 161(3)#1

C9‐H9…O2 0.93(3) 3.011(3) 2.404(3) 122.77#2

C16‐H16…O1 0.93(3) 3.548(4) 2.768(2) 142.02#3

Note: D: Donor, A: Acceptor

Symmetry transformations used to generate equivalent atoms: #1 ‐x+1,‐y+1,‐z+2 #2 X,Y,Z #3 –X+1, ‐Y+1,‐Z+2


Figure 3.3 Molecular Packing Diagram of 4MNBS crystal.


83

C8-N1 are in agreement with the experimental values (1.435, 1.427, 1.626, 1.747

and 1.419 Å). Petrov et al. [66] reported the molecular structure and

conformations of benzenesulfonamide by gas electron diffraction and quantum

chemical calculations and according to their results, the bond lengths, CS, SN, SO

vary in the range of 1.7756–1.7930, 1.6630–1.6925, 1.4284–1.4450 Å and the

bond angles, CSN, CSO, NSO, vary in the range, 103.9–107.1, 107.6–109.8,

105.5–107.7◦. These values are in agreement with the corresponding values for the

title compound. At C8 position, the bond angles C17–C8–N1, C9–C8–C17 and

C9–C8–N1 are 118.12, 120.619 and 121.249◦ respectively. This asymmetry in

angles reveals the interaction between NH group and naphthalene ring. The torsion

angles Ʈ1 (C6-C1-S1-N1) is calculated as 97.6° for B3LYP, which falls within the

expected range (70-120°). The torsion angles Ʈ1 (C7-C4-C5-C6) and Ʈ2 (C2-C3-

C4-C7) are -178.534 and 178.658° respectively for B3LYP. These torsion angles

are in agreement with the XRD data.

Further, the results of our calculations showed that S8- O9 and S8- O10

bonds show typical double bond characteristics and all other bond lengths fall

within the expected range. Some values deviates where comparing with the XRD

data and these differences are probably due to intramolecular interactions in the

solid state. In spite of the differences, calculated geometric parameters represent a

good approximation and they are the bases for calculating other parameters such as

vibrational frequencies and thermodynamic properties.

3.5 VIBRATIONAL ASSIGNMENTS

The FTIR spectrum of the sample was recorded in the KBr phase in the

frequency region of 450cm-1 – 4500cm-1 and the harmonic vibrational frequencies

calculated by using DFT/B3LYP with 6-31G (d, p) basic set are given in Table 3.4.


Table 3.4

Vibrational wavenumbers obtained for 4MNBS at B3LYP/6-31G(d,p)

[(harmonic frequency cm−1), IR intensities (Kmmol−1), Raman intensities

(arb. units)]

Experimental

(cm−1)

FT-IR

FT-Raman

DFT Calculated (cm−1) (scaled

IbIR Ic

Raman Vibrational assignments PED (%)

3294

3265

3065

2921

1513

3075

2921

1588

1524

1472

3415

3119

3097

3090

3078

3077

3064

3060

3059

3057

3053

3050

3006

2980

2921

1613

1587

1585

1562

1561

1498

1474

1444

1444

0.2

0.1

0.1

0.1

0.8

0.7

0.4

0.5

0.5

0.1

0.7

2.0

0.5

0.8

0.5

1.2

0.2

0.0

2.4

3.0

4.1

0.1

9.2

2.2

2.8

1.4

2.6

1.5

2.4

1.5

1.3

0.3

0.2

0.4

1.6

1.7

2.0

1.2

0.4

0.3

0.8

0.0

0.7

1.3

2.4

0.1

7.9

3.1

νNH(100)

νCH(97)

νCH(96)

νCH(95)

νCH(88)

νCH(78)

νCH(96)

νCH(96)

νCH(87)

νCH(87)

νCH(87)

νCH(84)

νCH(99)

νCH(99)

νCH(100)

νCC(38)+βNSC(13)

νCC(38)

νCC(54)

νCC(36)

νCC(14)+βHCC(11)+βSCC(10)

νNC(36)

βHCH(51)+ΒCCC(14)+ΒCNS(14)

ΒCCC(70)+ƮCCCC(14)


1413

1313

1142

1091

1019

914

1381

1319

1256

1223

1159

1100

1031

940

1442

1438

1383

1376

1370

1363

1350

1314

1295

1280

1258

1242

1209

1194

1186

1162

1151

1143

1129

1097

1096

1066

1046

1028

1022

1006

991

974

960

942

940

937

928

878

16.8

19.9

17.0

43.6

4.7

0.1

13.8

100.2

3.1

0.2

0.5

23.3

1.9

22.1

1.8

9.9

24.1

0.3

2.4

9.3

1.1

0.2

0.0

1.1

0.0

0.1

0.0

2.1

6.9

7.8

6.9

24.5

5.3

10.8

2.3

1.7

1.5

6.1

4.3

2.4

1.7

10.8

0.1

7.1

2.5

1.0

1.3

2.2

5.4

2.4

3.5

1.3

0.4

12.7

2.0

0.2

0.2

0.1

0.3

0.2

0.6

0.4

7.1

0.1

2.9

4.6

8.4

1.5

ΒHCC(28)

ΒCCC(75)

ΒHCC(12)+ΒHCH(29)

νCC(30)+βHCH(14)+βCCC(14)

ΒHCH(22)+ΒHCC(12)

ΒCCC(93)

νCC(30)+βHCC(11)

νCC(24)+βHCC(11)+βSCC(15)

νSN(17)+βCCC(17)

νCC(70)

βHCH(60)+ βCCC(19)

νSN(26)+βCCC(20)+βHCC(22)

βHCH(41)+ βSCC(13)

νCC(22)+νSO(16)+βHCC(31)

νCC(29)+βHCC(14)+βNSC(10)

νCC(10)+νSC(40)+βHCC(14)

νCC(14)+βCCC(18)+βHCH(53)

βHCC(44)

βHCC(42)+ βHCH(25)

νCC(16)+βHCH(48)

νSN(27)+βCCC(29)

νCC(29)+βHCH(39)+βCCC(12)

νCC(31)+βHCC(26)

νCC(38)+νSN(14)+βCCC(17)

νSO(13)+βHCC(19)+βCCC(13)

τCCCN(13)+ τCCCC(43)

νNC(45)

βCNS(19)+ βCCC(55)

νCC(11)+ τCCCN(12)+ τCCCC(37)

τCNSC(18)+ τHCCC(71)

τCCCC(72)+ τHCCC(19)

τHCCC(64)

τCCCC(61)+ τHCCC(17)+ τONOS(10)

τHCCC(77)


777

661

563

814

761

658

581

527

485

449

319

286

253

865

850

824

814

798

783

777

772

756

723

704

684

641

628

622

596

567

549

517

507

494

483

464

458

438

413

400

392

347

316

299

265

257

223

80.4

0.3

1.6

3.4

1.2

1.4

0.7

9.5

6.5

25.8

0.4

9.0

40.8

7.1

10.2

0.1

7.3

5.1

1.8

2.5

1.5

6.1

3.7

2.1

1.8

2.1

5.4

8.7

0.2

10.9

7.1

6.0

0.5

0.2

16.3

5.1

1.1

2.3

1.4

4.3

1.8

11.7

1.7

8.9

0.5

1.0

1.0

42.6

42.6

17.2

1.7

0.5

19.9

8.8

8.9

5.9

0.3

5.7

30.5

13.3

0.4

28.6

1.6

100.3

38.2

22.1

11.6

21.6

τHCCC(80)

νSO(10)+βHCC(11)+βCCC(24)

τHCCC(46)


βHNC(23)


νSC(13)+βCNS(25)

τHCCC(28)

νCC(11)+βCCC(17)+βOSO(29)

τHCCC(35)+ τCCCC(16)

τHCCC(39)

βHCC(15)

τONCS(18)+ τCCCC(47)

τONOS(25)

τCCNS(11)

βCCC(57)

τCCNS(15)

τCCCC(12)

τCCCC(12)

τONOS(17)

τHCCS(11)+ τCCCC(10)

βOSN(22)+ βOSO(12)

τHCCC(22)+ τONOS(16)

τCCCC(22)+ τCCNS(17)

τHCCS(23)

τSCCC(11)

τHCCC(12)+ τSCCC(16)+ τONCS(23)

τHCCC(14)+ τCCCC(13)+ τONOS(24)+ τONC

τSCCC(16)+ τONCS(23)

τHCCC(13)

τHCCC(44)+ τONCS(21)

τHCCS(15)

τHCCS(15)

τHNCC(10)+ τCCCC(11)


15

183

168

153

133

88

70

41

33

29

15

7.0

4.3

7.0

10.1

17.3

5.7

0.8

0.4

0.9

13.7

41.3

30.6

28.5

47.8

54.5

125.2

31.7

20.6

26.7

29.5

ΒCCN(15)+ΒNSC(10)

τHNCC(10)+ τCNSC(22)

τCCCC(29)+ τCNCC(17)

τNSCC(17)+ τSCCC(20)+ τHNCC(13)+ τHCC

τHCCC(10)+ τCCCC(25)

τNSCC(26)+ τSCCC(24)

τHNCC(22)+ τCCCC(24)+ τNSCC(10)

τCCCN(23)+ τCCCC(35)+ τNSCC(27)

τNSCC(17)+ τSCCC(20)+ τHNCC(13)+ τHCC

τNSCC(66)

τCCCC(12)+ τCCNS(79)


4000 3500 3000 2500 2000 1500 1000 500

Wavenumber(cm-1)

B3LYPTran

smis

sion

(arb

.uni

ts)

X Axis Title

Experimental

Figure 3.4(a) Experimental and Theoretical FTIR spectrum of 4MNBS


3500 3000 2500 2000 1500 1000 500

R

aman

Inte

nsity

(arb

.uni

t)

Wavenumber(cm-1)

B3LYP

Experiment

Figure 3.4(b) Experimental and Theoretical FT‐Raman Spectrum of 4MNBS.


84

The FTIR and FT Raman spectra of the 4MNBS compound are shown in

Fig.3.4. (a) and Fig 3.4 (b) The assignments of various bands in different

compounds, in general, have been reported in detail in the references [67-68].

3.5.1 N-H Vibration

As it is seen in Table 3.4, the N-H stretching mode, calculated as 3414 cm-1

is observed at 3294 cm-1. This difference between experimental and calculated

N-H stretching vibration (120 cm-1) can be due to N-H-O strong intermolecular

hydrogen bond which has not been taken into consideration in the calculation. As

expected, this is a pure stretching mode with a P.E.D contribution 100% and is

evident from P.E.D. table. In the literature, some N-H stretching modes observed

experimentally for the different substituent-sulfonamide are 3273 cm-1, 3343 and

3284 cm-1 [69]. Theoretical value for the N-H stretching vibration was reported as

3422 cm-1 by the method of B3LYP/6-31 G (d,p) level [70] .

3.5.2 C-H Vibration

The sulfonamide derivatives are gives rise to C–H stretching, C–H in-plane

and C–H out-of-plane bending vibrations. Aromatic compounds commonly

exhibit multiple weak bands in the region 3100–3000 cm−1 [71] due to aromatic

C–H stretching vibrations. In pure naphthalene has been occurred in the region

3080–3000 cm−1. They are not appreciably affected by the nature of the

substituents [72-–74]. All the C–H stretching vibrations are very weak in intensity.

In the present study, the 4MNBS has seven C–H vibrations for naphthyl ring and

four C-H vibrations for phenyl ring. All bands have very weak intensities and

were obtained in the expected region. As expected, these eleven modes (2–12

modes) are pure stretching modes with a PED contribution nearly 90%. as it is


85

evident from PED column. The C-H aromatic stretching modes are calculated as

3049–3118 cm-1 and they are observed at 3265, 3065 cm-1 in the IR spectrum and

the corresponding Raman band is observed at 3075 cm-1 (Table 3). The bands due

to C-H in-plane ring vibrations interacting with C-C stretching vibration which are

medium-weak intensity sharp bands in the region 1000-1300 cm-1. In general,

substitution patterns on the ring can be judged from the out-of-plane bending of the

ring C-H bond in the region 960-675 cm-1 and these bands are highly informative

[75]. C-H out-of-plane bending vibrations are strongly coupled vibrations and

occur in the region 900-667cm-1 [76]. Consequently, in this work, the peaks

appeared at 914, 777 cm-1 in FTIR and 940, 814, 761 cm-1 in FT Raman confirms

the C-H out of plane bending vibrations. Naphthalene CH stretching vibrations are

reported in the IR spectrum at 3259, 3171, 3067, 3057 and 3046 cm−1 as weak

bands and the corresponding Raman band is observed at 3058 cm−1 as strong band

as expected [69,70]. Krishnakumar et al. [71] reported 1055, 1037, 778, 742, 690,

675, 538, 488, 458, 355, 298, 257 cm−1 as in plane and out-of-plane ring

deformation bands of naphthalene ring. Ravikumar et al. [77] reported Raman

bands at 1440, 1420 and 1141 cm−1 and the IR bands at 1440, 1424, 1238, 1187,

1147 and 1140 cm−1 correspond to the naphthalene C–H in-plane bending modes,

which are mixed with other vibrational modes. In 1-substituted naphthalene

derivatives, the CH out-of-plane bending vibrations occur at 810–785 cm−1 due to

three adjacent hydrogen atoms on the ring, and at 780–760 cm−1 for four adjacent

hydrogen atoms [69]. The in-plane and out-of plane CH deformations are assigned

theoretically (B3LYP) at 1333, 1293, 1198, 1175, 1141, 1110 cm−1 and 999, 981,

978 884, 858 cm−1, respectively. For 4MNBS, these bands are observed at 1313,

777 in the IR and 1319, 1159, 1031, 814 cm−1 in the Raman spectrum.


86

3.5.3 C-C Vibration

The stretching C=C vibration gives rise to a band at 1513 cm-1 in the

infrared experimental spectrum, 1588 cm-1 in the Raman spectrum, while the

calculated values are at 1613, 1587, 1498 cm-1. The ring stretching vibrations are

expected within the region 1620–1390 cm−1 [67]. In the following discussion,

naphthalene ring and para substituted phenyl ring are designated as ring I and

ring II, respectively. The naphthalene ring modes are influenced more C–C bands.

Most of the ring modes are altered and missing by the substitutions to aromatic

ring of naphthalene. Generally the C–C stretching vibrations in aromatic

compounds form the strong bands. Govindarajan et al. [63] reported the C–C

stretching vibrations at 1564, 1490, 1417, 1340, 1261, 1212 and 1114 cm−1

experimentally and at 1570, 1496, 1424, 1354, 1269, 1213, 1120 cm−1 theoretically

for the naphthalene ring.

3.5.4 Methyl Group Vibrations

The C-H stretching in CH3 occurs at lower frequencies than those of

aromatic ring (3100-3000 cm-1). The vibrations of methyl group in this title

molecule are observed in the typical range reported in earlier literatures [75-77]. In

view with the literatures, the CH3 asymmetric stretching frequencies are

established at 3005 (FT-R), 2980 (FT-R), 2970 (FTIR) and 2950 cm-1 (FTIR)

whereas CH3 symmetric frequencies are assigned at 2950 (both) and 2920 cm-1

(FT-IR). For the compound 4MNBS, the weak band observed at 2931cm-1 in the

raman spectrum and 2921cm-1 in the IR spectrum are assigned to CH3 stretching

vibrations and calculated as 3006, 2979, 2920cm-1. The methyl group in-plane

bending vibrations comprises of in-plane asymmetric and symmetric bending

deformations. In this work, the strong bands appeared at 1472 cm-1 in Raman,


87

1413 cm-1 in FTIR and 1444cm-1 in B3LYP are assigned to CH3 in-plane bending

deformation vibrations which coincides with the values stated in the earlier

literatures [75-78], where the asymmetric deformation of CH3 group was observed

at around 1450 cm-1 for methyl substituted aromatic rings. The peak at 1381 cm-1

(FT-IR) is assigned to CH3 symmetrical methyl deformation vibrations, calculated

as 1369 cm-1.

3.5.5 Heavy Atoms Fundamentals Vibrations

The antisymmetric and symmetric stretching modes of SO2 group appear in

the region 1360–1310 and 1165–1135 cm−1, respectively [79]. The SO stretching

mode is not pure, but contains contributions from other modes also. The two bands

attributed to the SO stretching vibrations, appearing at 1313 and 1142 cm-1 in IR

spectrum, 1319, 1159 cm-1 in Raman spectrum are calculated as 1314 and

1096 cm-1 respectively (Table 3). The strong peak at 1313cm-1 is mainly because

of the asymmetric stretching vibration of SO2 group. The moderate band at

1142 cm-1 is assigned to the symmetric stretching vibration of SO2 group. CN

stretching vibration appears at 1091 cm-1 as a moderate intensity. The moderate

peak at 1019 cm-1 is due to the out of plane bending vibrations of CH and CN. The

band at 914 cm-1 shows SN and CH out of plane bending vibrations and 777 cm-1

is due to the in plane bending vibration of the aromatic rings. The strong peak at

661 cm-1 is due to the out of plane bending vibrations of CS and CN. The strong

Peak at 563 cm-1 in IR and medium band at 527cm-1 in the Raman spectrum are

mainly because of the wagging motion of SO2 group and out of plane bending

vibration of aromatic ring. The wagging motion of SO2 group calculated as

528 and 477 cm-1. The absorptions at the above mentioned frequencies suggest the

presence of functional groups corresponding to both -SO2 and N-H indicating the


88

formation of sulfonamide. The above conclusions are in good agreement with the

similar sulfonamide compounds [80].

3.6 FT NMR SPECTRAL ANALYSIS

1H NMR spectrum provides information about the number of different

types of protons and also the nature of immediate environment to each of them. 13C

NMR spectrum also provides the structural information with regard to different

carbon atoms present in the molecules. The experimental 13C and 1H spectra are

presented in Fig.3.5 (a) and Fig. 3.5 (b) respectively. The theoretical 13C and 1H

chemical shift values (with respect to TMS) of the title compound are generally

compared to the experimental13C and 1H chemical shift values. The results in

Table 3.5, show that the range 13C NMR chemical shift of typical organic molecule

is usually >100ppm [81]; the accuracy ensures reliable interpretation of

spectroscopic parameters. It is true from the above literature value, in our present

study, the title molecule also falls with the above literature data.

In the 1H NMR spectrum, a singlet at 2.3δ indicates the three protons of

methyl group. The above said, methyl group protons are calculated in the range of

1.7 δ-2.07 δ for B3LYP. The eleven aromatic protons of naphthyl and tolyl group

are appeared as multiplet in the range of 7-8 δ and are found to be in the range of

7.52-8.29 δ for B3LYP. The NH group of the naphthyl is responsible for the

appearance of broad singlet at 7.25δ and calculated as 4.7 δ for B3LYP.

In the 13C NMR spectrum, the methyl carbon of the tolyl group give signal

at 20δ, calculated as 10.89 δ. The sixteen aromatic carbons of napthyl and tolyl

group are appeared as multiplet in the range of 121.59-143.79δ and are found to be

in the range of 109.99-132.71 δ for B3LYP. The signal at143.79 δ is assigned to


Table 3.5

The chemical shift in 1H NMR and 13C NMR spectrum of 4MNBS

Spectrum Experimental (CDCl3)

Signal at δ(PPM)

B3LYP

Calculated chemical shift at

δ(PPM)

Group Identification

1H NMR

2.3 (singlet) 1.7 - 2.07 3 protons of methyl group

7- 8 ( multiplet) 7.52 -8.29 10 aromatic protons

7.25( broad singlet) 4.706 For N-H proton 13C NMR

20 10.899 methyl carbon of the tolyl group

143.79 132.71 C8 carbon of the naphthyl ring attached with NH group

136.35 128.03 C4 carbon of the tolyl ring attached with methyl group

134.23 121.94 C1 carbon of the tolyl ring attached with SO2 group

129.57 115.88 C3,C5 (meta) carbons of the tolyl ring

125.38 112.67 C2,C6 (ortho) carbons of the tolyl ring

125.43 112.91 C16 carbon of the naphthyl ring





126.64 114.71 C15 Carbon of the naphthyl ring




76-78 79.86 Carbon of the solvent CDCl3


Figure 3.5 (b) 13C NMR spectrum of 4MNBS.


Figure 3.5(a) 1H NMR spectrum of 4MNBS.


89

the C8 carbon of naphthyl ring which is bonded with NH group, calculated as

132.71 δ. The signal at 136.35δ is assigned to the C4 carbon of tolyl ring which is

bonded with methyl group, calculated as 128.03 δ. The signal at 134.23δ is

assigned to the C1 carbon of tolyl ring which is bonded with sulfonyl group,

calculated as 121.94 δ. The Meta carbons (C3, C5) of the tolyl ring are responsible

for the signal at 129.57δ, calculated as 115.88 δ. The ortho carbons (C2, C6) of the

tolyl ring are responsible for the signal at 128.38 δ, calculated as 112.67 δ. The

signals at 131.51δ, 128.9δ, 127.16δ and 126.64 δ, are assigned to the (C12-C15)

carbons of the naphthyl ring. The above said carbons of the naphthyl ring are

calculated as, 118.43 δ, 114.9 δ, 114.81 δ and 114.71 δ for B3LYP. The C16 and

C17 carbons of the naphthyl ring are responsible for the signals at 125.43δ and

126.28 δ respectively. The signals at 121.59 δ, 127.37 δ and 122.65 δ are assigned

to the carbons C9, C10 and C11 of the naphthyl ring. The above said relevant

calculated 13C chemical shifts are listed in the table. (See ortep diagram for

numbering of atoms). A Signal at 76-78 δ indicates the carbon atom of the CDCl3

(solvent), calculated as 79 δ. As it is seen from Table, calculated 1H and 13C

chemical shifts values of the title compound are generally agreement with the

experimental 1H and 13C chemical shifts data.

3.7 NBO ANALYSIS

NBO analysis provides a possible ‘natural Lewis structure’ picture of ø,

because all orbital details are mathematically chosen to include the highest possible

percentage of the electron density. A useful aspect of the NBO method is that it

gives information about interactions in both filled and virtual orbital spaces that

could enhance the analysis of intra- and intermolecular interactions.


90

The second order Fock matrix was carried out to evaluate the donor–

acceptor interactions in the NBO analysis [82]. The interactions result is a loss of

occupancy from the localized NBO of the idealized Lewis structure into an empty

non-Lewis orbital. For each donor (i) and acceptor (j), the stabilization energy E

(2) associated with the delocalization i→j is estimated as

E(2) = ∆Eij = qi ⎟⎟⎠

⎞⎜⎜⎝

⎛

− )(),( 2

ij

jiFεε (3.1)

where qi is the donor orbital occupancy, are εi and εj diagonal elements and F(i, j)

is the off diagonal NBO Fock matrix element.Natural bond orbital analysis

provides an efficient method for studying intra and intermolecular bonding and

interaction among bonds, and also provides a convenient basis for investigating

charge transfer or conjugative interaction in molecular systems. Some electron

donor orbital, acceptor orbital and the interacting stabilization energy resulted from

the second-order micro-disturbance theory are reported [83,84]. The larger the E(2)

value, the more intensive is the interaction between electron donors and electron

acceptors, i.e. the more donating tendency from electron donors to electron

acceptors and the greater the extent of conjugation of the whole system.

Delocalization of electron density between occupied Lewis type (bond or lone pair)

NBO orbitals and formally unoccupied (antibond or Rydgberg) non-Lewis NBO

orbitals correspond to a stabilizing donor–acceptor interaction.

NBO analysis has been performed on the molecule at the DFT/B3LYP/

6-31G (d,p) level in order to elucidate the intra molecular, rehybridization and

delocalization of electron density within the molecule. The intra molecular

interaction are formed by the orbital overlap between (σ and π (C–C, C-H and

C-N) and σ* and π* of C-C, C-H and C-N)) bond orbital which results intra


Table 3.6


91

molecular charge transfer (ICT) causing stabilization of the system. These

interactions are observed as increase in electron density (ED) in C–C anti bonding

orbital that weakens the respective bonds [85]. The electron density of conjugated

double as well as single bond of the aromatic ring (~1.9e) clearly demonstrates

strong delocalization inside the molecule.

The strong intramolecular hyperconjugation interaction of the σ and π

electrons of C–C to the anti C–C bond in the ring leads to stabilization of some

part of the ring as evident from Table 3.6. For example, the intra molecular hyper

conjugative interaction of σ (C1–C2) distribute to σ* (C3–C10) and (C1–C2)

leading to stabilization of ~3.0 kJ/mol. This enhanced further conjugate with anti-

bonding orbital of π* (C3–C4) and (C5–C6), leads to strong delocalization of

17.36 and 19.11 kJ/mol respectively. The magnitude of charges transferred from

lone pair nitrogen LP (1) N18 shows that stabilization energy of about ~ 7 KJ/Mol.

Where as in the case of LP (2) O35 the stabilization energy of about ~ 19 KJ/Mol

which clearly manifests the evidence for the elongation of the bond S20-C21. The

delocalization of electron π*(C1-C2) to π*(C3-C4) with enormous stabilization

energy of about ~ 299 KJ/Mol. (see Fig.3.2 for numbering of atom).

3.8 HYPERPOLARIZABILITY CALCULATIONS

The first order hyperpolarizability (βtotal) along with related properties (μ,

⟨α⟩ and Δα) are calculated by using DFT-B3LYP method with 6-31G(d,p) basis

set, based on the finite-field approach. In the presence of an applied electric field,

the energy of a system is a function of the electric field. First order

hyperpolarizability is a third rank tensor that can be described by a 3 × 3 × 3 array.

The 27 components of the 3D matrix can be reduced to 10 components due to the

Kleinman symmetry [67]. It can be given in the lower tetrahedral format.


92

The components of βtotal are defined as the coefficients in the Taylor series

expansion of the energy in the external electric field. When the external electric

field is weak and homogeneous, this expansion becomes:

E = E0 - μαFα - 1/2ααβFαFβ - 1/6βαβγFαFβFγ + … (3.2)

where E0 is the energy of unperturbed molecule, Fα the field at the origin, μα, ααβ ,

and βαβγ are the components of dipole moment, polarizability and the first order

hyperpolarizabilities, respectively. The total static dipole moment μ, the mean

dipole polarizability (α), the anisotropyof the polarizability Δα and the total first

order hyperpolarizability βtotal, using x, y, z components they are defined as

μ = (μx2+ μy2+ μz2)1/2, (3.3)

3zzyyxx ααα

α++

= (3.4)

Δα = 2-1/2 [(αxx - αyy)2 + (αyy - αzz)2 + (αzz - αxx)2 + 6 ]1/2 (3.5)

( ) 2/1222zyxtotal ββββ ++= (3.6)

And

β x = β xxx + β xyy + β xzz, (3.7)

β y = β yyy + β xxy + β yzz, (3.8)

β z = β zzz + β xxz + β yyz (3.9)


93

The calculated dipole moment, polarizability and first order

hyperpolarizability values obtained from B3LYP/6-31G(d,p) method are collected

in Table 3.7. The total molecular dipole moment of 4MNBS from B3LYP with 6-

31G(d,p) basic set is 1.543D, which is nearer to the value for urea (µ = 1.3732 D).

Similarly the first order hyperpolarizability of 4MNBS is 3.3336 x 10-30

which is nearly 4 times greater than the value of urea

(β = 6.09×10−30 esu). From the computation the high values of the

hyperpolarizabilities of 4MNBS are probably attributed to the charge-transfer

existing between the phenyl rings within the molecular skeleton. So we conclude

that the title compound is an attractive object for future studies of nonlinear optical

properties.

3.9 MULLIKEN ATOMIC CHARGES

Mulliken atomic charge calculation plays an important role in the

application of quantum mechanical calculations to molecular systems [87]. The

calculated Mulliken charge values of 4MNBS are listed in Table 3.8. The charge

distribution structure is shown in Fig 3.6. The Mulliken atomic charge analysis of

4MNBS shows that the presence of two oxygen atoms in the sulphonamide moiety

(O21 = −0.5453); (O22 =−0.5251) imposes positive charge on the sulfur atom S8 =

1.1821. However, the carbon atoms C1, C2, C6, C10, C11, C14, C15, C23, C24,

C25, C26, and C28 posses small negative charges, whereas carbon atoms C3, C4,

and C5 posses positive charge due to large negative charge (-0.6858) of N18.

Moreover, there is no difference in charge distribution observed on all hydrogen

atoms except the H19 and methyl group hydrogens (H32, H33 and H34). The large

positive charges on H19 (0.2894) and H33 (0.1419) is due to large negative charge

accumulated on the N18 atom and C31 (methyl carbon) atom respectively.


Table 3.7

The electric dipolemoment(D), Polarizability and first hyperpolarizability of 4MNBS

a.u esu(x10-24) a.u (esux10-33)

αxx 249.72 1685.011 Βxxx 24.28 209.7622

αxy -5.58 -37.6516 Βxxy -9.49 -81.987

αyy 127.74 861.9384 Βxyy 96.93 837.4073

αxz -53.68 -362.211 Βyyy 33.21 286.9112

αyz 9.57 64.57453 Βxxz -72.07 -622.634

αzz 252.63 1704.646 Βxyz 35.41 305.9176

αtotal 210.3 1419.02 Βyyz -47.24 -408.121

µx 1.895 Βxzz 5.76 49.76237

µy .906 Βyzz -41.41 -357.753

µz -0.237 Βzzz -163.61 -1413.48

µ 2.109 Βtotal 310.6 2683.44


Table 3.8

Mulliken Atomic Charges of 4MNBS

Atoms Charges C1 C2 C3 C4 C5 C6 H7 H8 H9 C10 C11 H12 C13 C14 H15 H16 H17 N18 H19 S20 O21 O22 C23 C24 C25 C26 H27 C28 H29 C30 H31 H32 C33 H34 H35 H36

0.120541-0.125960.1074330.1217610.10216

-0.069990.0855090.0902680.081804-0.14064-0.131950.180254-0.09055-0.089470.0947690.0825240.082553

-0.68590.28947

1.182135-0.54531-0.52511-0.16389-0.08147-0.08852-0.102740.143426

-0.10380.1069290.1038810.099536

0.0964-0.375230.1250750.1419810.123185


94

3.10 MOLECULAR ELECTROSTATIC POTENTIAL

Molecular Electrostatic potential at the B3LYP/6-31G (d,p) optimized

geometry was calculated. The molecular electrostatic potential (MEP) is related to

the electronic density and a very useful descriptor for determining sites for

electrophilic attack and nucleophilic reactions as well as hydrogen–bonding

interactions (88-91). As it is seen in Figure 3.7, the red region is localized on the

oxygens of the sulfonyl group has value of -.0994a.u. and the maximum blue

region localized on the N1-H1 bond has value of +.0993 a.u, indicating the

possible sites for electrophilic attack and nucleophilic reaction respectively. These

sites give the information about the region, from where the compound can have

intermolecular interactions. Hence, the molecular electrostatic potential map

confirms the existence of intermolecular N-H…O interactions.

3.11 ELECTRONIC ABSORPTION SPECTRA

To provide better insights into the nature of the UV-Vis absorptions spectra

observed experimentally, the low energy electronic excited states of EPAB have

been calculated at the B3LYP/6-31G(d,p) level using the TD-DFT approach on the

previously optimized groundstate geometry of the molecule. Position and

absorbance of the experimental peaks shown in (Figure-3.8). TD-DFT calculations

predict three transitions in the near ultraviolet region for 4MNBS molecule. The

strong transitions at 215 nm with an oscillator strength f=0.2910 in gas phase are

assigned to an n to π*. The experimental absorption spectrum shows broad

absorption peaks around at 285 nm is observed owing to n to π*.


Figure 7 Molecular Electrostatic potential (MEP) of 4MNBS


200 250 300 350 400 450 500 550 600-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

285

223A

bsor

banc

e

Wavenumber(cm-1)

Figure 3. 8 UV‐Vis absorption spectrum of 4MNBS


95

3.12 FRONTIER MOLECULAR ORBITALS (FMOs)

Both the highest occupied molecular orbitals (HOMOs) and lowest

unoccupied molecular orbitals (LUMOs) are the main orbitals taking part in

chemical stability. The HOMO represents the ability to donate an electron, LUMO

as an electron acceptor representing the ability to obtain an electron.

This electronic absorption corresponds to the transition from the ground to

the first excited state and is mainly described by one electron excitation from the

highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular

orbital (LUMO). The HOMO is located over the naphthalene ring, NH and SO2

group. Lumo is delocalized on the entire compound except the CH2 of the methyl

group. The HOMO to LUMO transition implies an electron density transfer from

the naphthyl amino moiety to toluene sulfonyl moiety. Figure 3.8 shows the

surfaces of HOMO and LUMO. The HOMO - LUMO energy gap explains the

eventual charge transfer interactions taking place within the molecule. The HOMO

and LUMO energy are 5.5547 eV and 1.3154 eV at the DFT level (Table 3.3). The

DFT level calculated energy gaps 4.2392 eV shows the lowering of energy gap and

reflect the NLO activity of the molecule.

3.13 GLOBAL REACTIVITY DESCRIPTORS

Conceptual density functional theory and reactivity indices Parr et al and

other researchers [92-94] suggested that DFT methods and reactivity indices are

conceptually insightful and practically convenient to predict the chemical reactivity

of molecules. It was anticipated that some reactivity indices are equally important

for understanding structural changes. Electronic chemical potential (μ), one of the

reactivity indices, refers to the escaping tendency of electrons from equilibrium


Figure 3.9 HOMO‐LUMO Surfaces of 4MNBS.

Energy Gap = 4.23 eV

LUMO Energy =1.31eV eV

LUMO Plot

HOMO Energy = 5.55 eV

HOMO Plot

l


96

and is identified as the negative of electronegativity (χ = −μ). Chemical hardness

(η) measures the resistance of μ to change in total number of electrons. Several

studies have employed these parameters to describe the molecular reactivity by

obtaining η and χ values from semi-empirical data, the frontier molecular orbital

(FMO) energies.

The theoretical definitions of μ and η are provided by the DFT as the first

and second derivatives of the electronic energy with respect to the number of

electrons (N) for a constant external potential V(r):

External potential V(r);

µ = -χ = ην

,⎟⎠⎞

⎜⎝⎛

∂∂NE = ⎟

⎠⎞

⎜⎝⎛

∂∂

=⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

NNE μ

2

2

(3.1)

The electrophilicity index (ω) derived by Parr et al [94] takes the following

form:

⎟⎟⎠

⎞⎜⎜⎝

⎛=⎟⎟

⎠

⎞⎜⎜⎝

⎛=

ηχ

ημω

22

22

(3.2)

Based on the finite difference approach method, the working equations for

calculating μ and η are given by

2AI +

−=μ (3.3)

and

AI −=η (3.4)


97

where I and A are the first ionization potential and the electron affinity,

respectively. Under Koopmans’ theorem, the above equations can be expressed as

2LUMOHOMO EE +

−=μ (3.5)

and

HOMOLUMO EE −=η (3.6)

where E HOMO and E LUMO designate the energies of the highest occupied and

lowest unoccupied molecular orbits, respectively. In addition, two new reactivity

indices related to electrophilicity and nucleophilicity, as well as electrofugality and

nucleofugality in terms of the reactant’s first ionization potential (I) and electron

affinity (A), have recently been introduced by Ayers et al. [95]. Electrofugality ΔEe

is defined as

( )ηημω

2

2−=+=Δ IEe (3.7)

Nucleofugality ΔEn is defined as

( )ηημω

2

2+=+−=Δ AEn (3.8)

These equations assess the quality of electron-fleeing and electron-

accepting, respectively.

Using the above equations, the chemical potential, hardness and

electrophilicity index have been calculated for 4MNBS and their values are shown


98

in Table 3.9. The ionization potential calculated by B3LYP/6-31G(d,p) method

for 4MNBS is -5.5 eV

3.14 THERMAL ANALYSIS

Thermal analysis of 4MNBS was carried out using a Perkin Elmer model,

simultaneous thermo gravimetric / differential thermal (TG/DT) analyser. The

sample was scanned in the temperature range 30-600oC at a rate of 20oC for

0.5 sec. The TG/DT curve is shown in Figure 3.9. The first endothermic peak

observed at 152.1oC is attributed to the melting point of the 4MNBS crystal. At the

melting point, no weight loss was observed in the TG curve. The weight loss starts

around 295oC and the major weight loss (92.2%) takes place over a large

temperature range (295-400oC), where almost all the compounds decomposed as

gaseous products. The endothermic peak corresponding to major weight loss was

observed at 400oC in the DT curve. The 4MNBS is chemically stable up to 295oC,

above which temperature the sample gradually decomposes. No exothermic or

endothermic peak was observed below the melting point endotherm, indicating the

absence of any isomorphic phase transition in the sample.

3.15 CONCLUSION

4 methyl-N-(naphthalene-1-yl) benzene Sulfonamide has been synthesized

and characterized by FTIR, NMR and X-ray single-crystal diffraction. The crystal

structure is stabilized by N-H---O type hydrogen bonds. X-ray, FTIR and NMR

spectral data of the title compound indicate that the compound formed is

sulfonamide. The optimized geometrical parameters (B3LYP) are in agreement

with that of reported similar derivatives. The influences of the electronegative NH

group and naphthalene ring to the structural parameters of the title compound were


Figure 3.10 TGA and DTA plot of 4MNBS


99

discussed. And also, optimized geometrical parameters were compared with the

experimental values. Theoretical (B3LYP) structural parameters and scaled

vibrational frequencies are in agreement with the experimental values. Any

discrepancy noted between the observed and the calculated values may be due to

the fact that the calculations were actually done on a single molecule in the

gaseous phase contrary to the experimental values recorded in the solid state where

the presence of intermolecular Coulombic interactions. The considerable

differences between experimental and calculated results of FTIR can be attributed

to the existence of N-H--O type intermolecular hydrogen bonds in the crystal

structure. Theoretical 1H and 13C chemical shift values (with respect to TMS) were

reported and compared with experimental data, showing good agreement for both 1H and 13C. The comparison between experimental results and theoretical data

presents that the calculation level preferred is powerful approach for understanding

the identification of all the molecules studied in this work. NBO result reflects the

charge transfer mainly due to C-C group. Atomic charges are also determined for

the identification of the molecule. Moreover, frontier molecular orbitals and

molecular electrostatic potential were visualized. Electronic transition and energy

band gap of the title molecule were investigated and interpreted. HOMO–LUMO

gap with 4.23 eV indicates that the title compound has a good chemical stability.

The tile compound is chemically stable up to 295°C. In conclusion, all the

calculated data and experimental results not only show the way to the

characterization of the molecule but also useful in the application in industry and

fundamental researches in chemistry and biology in the future.


100

REFERENCES

1. Hansch, C.; Sammes, P. G.; Taylor, J. B. In Comprehensive Medicinal

Chemistry; Pergamon Press: Oxford, 1990; Vol. 2;

2. Connor, E. E. Sulfonamide Antibiotics Prim. Care Update Ob. Gyn. 1998,

5, 32–35;

3. Hanson, P. R.; Probst, D. A.; Robinson, R. E.; Yau, M. Tetrahedron Lett.

1999, 40, 4761–4764.

4. Pharmaceutical Substances, Syntheses, Patents, Applications; Kleemann,

A., Engel, J., Kutscher, B., Reichert, D.,Eds.; Thieme: Stuttgart, 1999.

5. Roush, W. R.; Gwaltney, S. L.; Cheng, J.; Scheidt, K. A.; McKerrow, J. H.;

Hansell, E. J. Am. Chem. Soc. 1998, 120, 10994–10995

6. Roush, W. R.; Cheng, J.; Knapp-Reed, B.; Alvarez-Hernandez, A.;

McKerrow, J. H.;Hansell, E.; Engel, J. C. Bioorg. Med. Chem. Lett. 2001,

11, 2759–2765.

7. Cremlyn, R. Organosulfur Chemistry: An Introduction; John Wiley and

Sons: New York, 1996.

8. Anderson, K. K. In Sulfonic Acids and Their Derivatives in

Comprehensive Organic Chemistry; Barton, D. H. R., Ollis, W. D., Jones,

D. N., Eds.; Pergamon Press: Oxford, 1979;Vol. 3.

9. V. Krishnakumar, N. Prabavathi, S. Muthunatesan, Spectrochim. Acta 70

(2008) 991–996.

10. M. Arivazhagan, V. Krishnakumar, R.J. Xavier, G. Ilango, V.

Balachandran, Spectrochim. Acta A 72 (2009) 941–946.

11. M. Govindarajan, K. Ganasan, S.M. Periandy, M. Karabacak, Spectrochim.

Acta A 79 (2011) 646–653.


101

12. Dorota Maciejewsk, Jerzy Kleps, Journal of Molecular Structure 471

(1998) 67-71.

13. D. Shoba, M. Karabacak, S. Periandy, S. Ramalingam, Spectrochim. Acta

A 81 (2011) 504–518.

14. Srivastava, V.B. Singh, Indian J. Pure Appl. Phys. 45 (2007) 714–720.

15. Ravikumar, L. Padmaja, I. Hubert Joe, Spectrochim. Acta A 75 (2010)

859–866.

16. E. Kavitha, N. Sundaraganesan, S. Sebastian, M. Kurt, Spectrochim. Acta

A 77 (2010) 612–619.

17. M.H. Jamroz, J.Cz. Dobrowolski, R. Brzozowski, J. Mol. Struct. 787

(2006) 172–183.

18. V. Krishnakumar, N. Prabavathi, S. Muthunatesan, Spectrochim. Acta A 69

(2008) 528–533.

19. J.H.S. Green, D.J. Hurison, Spectrochim. Acta 26 (1970) 1925–1937.

20. G.C. Pimental, Abstracts of OSU International symposium on Molecular

Spectroscopy D7 (1951) 1946-1959.

21. Harrell Sellers, Peter Pulay, James E. Boggs, J. Am. Chem. Soc., 107

(1985) 6487-6494

22. T.Prabhu, S. Periandy, S. Mohan, Spectrochimica Acta Part A 78 (2011)

566-574.

23. R.L. Ward, Abstracts of OSU International Symposium on Molecular

Spectroscopy, vol. B4, 1956, pp. 1946–1959.

24. D.E. Freeman, I.G. Ross, Abstracts of OSU International symposium on

Molecular Spectroscopy, vol. C10, 1959, pp. 1946–1959.


102

25. R. Shanker, R.A. Yadav, I.S. Singh, O.N. Singh, Pramana 24 (1985) 749–

755.

26. M.V. Zhigalko, O.V. Shishkin, L. Gorb, Jerzy, J. Mol. Struct. 693 (2004)

153–159.

27. S.D. Christesen, C.S. Johnson Jr., J. Raman Spectrosc. 14 (2005) 53–58.

28. G. Cardini, V. Schettino, J. Raman Spectrosc. 15 (2005) 237–240.

29. A.V. Szeghalmi, V. Engel, M.Z. Zgierski, J. Popp, M. Schmitt, J. Raman

Spectrosc. 37 (2006) 148–160.

30. F. Ehland, S. Hassing, W. Dreybrodt, J. Raman Spectrosc. 30 (1999)

573–579.

31. H. Torii, Y. Ueno, A. Sakamoto, M. Tasumi, Can. J. Chem. 82 (2004)

951–963.

32. I.A. Zavodov, V.V. Zverev, L.I. Maklakov, J. Struct. Chem. 44 (2003)

388–396.

33. O. Scheneep, D.S. McClure, J. Chem. Phys. 20 (1952) 1375.

34. G.S. Jas, K. Kuczera, Chem. Phys. 214 (1997) 229–241.

35. P.B. Nagabalasubramanian, M. Karabacak, S. Periandy, Spectrochim. Acta

A 82 (2011) 169–180.

36. P. Das, E. Arunan, P.K. Das, Vib. Spectrosc. 47 (2008) 1–9.

37. V. Librando, A. Alparone, Environ. Sci. Technol. (2007).

38. V. Librando, A. Alparone, Polycycl. Aromat. Compd. 27 (1) (2007) 65–94.

39. P.B. Nagabalasubramanian, S. Periandy, Spectrochim. Acta A 77 (2010)

1099–1107.


103

40. G.M Sheldrick, SHELXS97 and SHELXL97, Programme for solution and

refinement of crystal structure, University of Gottingen, Germany, 1997.

41. A.L Spek, J Appl Cryst Sect, 36 (2003) 7-13.

42. M.J. Frisch et al, Gaussian 03W, Revision C.02. Gaussian Inc, Wallingford,

2004.

43. H.B. Schlegel, J.Comput.Chem 3(1982) 214-218.

44. P.Hohenberg, W. Kohn, Phys. Rev 136 (1964) B864-B871.

45. A.D.Becker, J.Chem.Phys 98 (1993) 5648-5652.

46. C. Lee, et al, Phys Rev B 37 (1988) 785-789.

47. Frisch, et al, Gauss view user manual, Gaussian Inc, Pittsburgh, PA, 2000.

48. E.D.Glendening, A.E.Reed, J.E.Carpenter, F.Weinhold, NBO version 3.1,

TCI, University of Wisconsin, Madison, 1998.

49. C.K.Johnson, ORTEPII. Report ORNL, 5138. Oak Ridge, National

Laboratory, Tennessee, USA, 1976.

50. Subhashini, M. Hemamalini, P. T. Muthiah, G. Bocelli, A. Cantoni, J.

Chem. Crystallogr 39 (2009) 112-116.

51. F.H. Allen, O. Kennard, D.G Watson, L. Brammer, A.G. Orpen, R. Taylor,

J. Chem. Soc 2 (1987)1-12.

52. C. Chatterjee, J.K. Dattagupta, N.N Saha, Acta Crystallogr Sect B 38

(1982) 1845-1847.

53. M. Haridas, R.K. Tiwari, T.P Singh, Acta Crystallogr Sect C 40 (1984)

658-660.

54. M. Ghosh, A.K. Basak, S.K Mazumdar, Acta Crystallogr Sect C 47 (1991)

577-580.


104

55. E. Kendi, S. Ozbey, O. Bozdogan, R. Ertan, Acta Crystallogr Sect C 56

(2000) 457-458.

56. M. Takasuka, H. Nakai, Vib Spectrosc 25 (2001) 197-204.

57. S. Ozbey, A. Akbas, G.Ayhan-Kilcigil, R.Ertan, Acta Crystallogr Sect C 61

(2005) 559-561.

58. T.P Singh, U. Patel, M. Haridas, Acta Crystallogr Sect C 40 (1984) 2088-

2091.

59. Glidewell, John N. Low, Janet M.S. Skakle and James L. Wardell,

Acta.Cryst. C 60 (2004) o33-o34.

60. V.L Abramenko, V.S Sergienko, Russ. J. Inert. Chem 47 (2002) 905-911.

61. Kalman, M. Czugler, G. Argay, Acta Crystallogr Sect B, 37 (1981) 868-

877.

62. C.A Hunter, Chem. Soc Rev, 23 (1994) 101-109.

63. M.Govindarajan, M.Karabacak, Spectrochim.Acta A 85(2012) 251-260.

64. Asha Chandran, Hema Tresa Varghese, Y. Sheena Mary, C.Yohannan

Panicker, T.K.Manojkumar, Christian Van Alsenoy, G. Rajendran,

Spectrochim.acta A 87 (2012) 29-39.

65. B.T. Loughrey, M.L. Williams, P.C. Healy, Acta Cryst. E65 (2009) o2087–

o2096.

66. V. Petrov, G.V. Girichev, H. Oberhammer, N.I. Giricheva, S. Ivanor,

J.Org. Chem. 71 (2006) 2952–2956.

67. R.M. Silverstein, G.C. Basle, and T.C. Morrill, Spectrometric Identification

of organic compounds, John Wiley and Sons, New York, 1991.

68. W. Kemp, Organic Spectroscopy, MacMillan, London, 1996.


105

69. G.E Came, Ramírez de Arellano, C. M.del, S.Fustero, J.C. Pedregosa, An.

Asoc. Quím. Argent 94(2006) 4-6.

70. M. Karabacak, M. Cinar, M.Kurt, J.Mol. Struct 984 (2010) 137-145.

71. V. Krishnakumar, R.J. Xavier, Indian J. Pure Appl. Phys. 41 (2003) 597.

72. N.B. Colthup, L.H. Daly, S.E. Wiberley, Introduction to Infrared and

Raman Spectroscopy, Academic Press, New York, 1990.

73. F.R. Dollish, W.G. Fateley, F.F. Bentley, Characteristic Raman

Frequencies of Organic Compounds, Wiley, New York, 1997.

74. G. Varsanyi, Vibrational Spectra of Benzene Derivatives, Academic Press,

NewYork, 1969.(from govind 43-46 for ch)

75. M. Pagannone, B. Formari, G.Mattel, Spectrochim. Acta A 43 (1986) 621.

76. P.S. Kalsi, Spectroscopy of Organic Compounds, Wiley Eastern Limited,

New Delhi, 1993.

77. M. Snehalatha, C. Ravikumar, I. Hubert Joe and V.S. Jayakumar, J. Raman

Spectrosc.40 (2009) 1121 – 1126.

78. D. Lin-Vien, N.B. Colthup, W.G. Fateley, J.G. Grasselli, The Hand Book

of Infrared and Raman Characteristic Frequencies of Organic Molecules,

Academic Press, Boston, 1991.

79. M. Dien, Introduction to Modern Vibrational Spectroscopy, Wiley, New

York, 1993.

80. H.A. Dabbagh, A. Teimouri, R. Shiasi, A. Najafi Chermahini, J. Iran.

Chem. Soc 5 (2008) 74-82.

81. B. T Gowda, K. Mythoi, J.D. D’ Souza, Z. Naturforsch. 57a (2002) 967–

973.


106

82. M. Szafran, A. Komasa, E.B. Adamska, J. Mol. Struct: Theochem 827

(2007) 101-107.

83. C. James, A. Amal Raj, R. Reghunathan, I.H. Joe, V.S. Jayakumar, J.

RamanSpectrosc. 37 (2006) 1381-1392.

84. J.-n. Liu, Z.-r. chen, S.-f. yuan, J. Zhejing, Univ. Sci. 6B (2005) 584-589.

85. S. Sebastian, N. Sundaraganesan, Spectrochim. Acta A 75 (2010) 941-952.

86. D.A. Kleinman, Phys. Rev. 126 (1962) 1977-1979.

87. R. Meenakshi, Mol. Simulat. 36 (6) (2010) 425-433.

88. E. Scrocco, J. Tomasi, Adv. Quantum Chem. 11 (1978) 115–121.

89. F.J. Luque, J.M. Lopez, M. Orozco, Theor. Chem. Acc. 103 (2000)

343–345.

90. N. Okulik, A.H. Jubert, Int. Electron. J. Mol. Des. 4 (2005) 17–30.

91. J.S. Murray, Z. Peralta-Inga, P. Politzer, Int. J. Quant. Chem. 75 (3) (1999)

267–273.

92. R.G Parr, R.A.Donnelly, M.Levy, W.E.Palke (1978) J. Chem Phys 68:

3801–3807.

93. R.G. Parr, R.G. Pearson, J Am Chem Soc 105 (1983) 7512–7516.

94. R.G. Parr, L.V. Szentpaly, S.B.Liu, Electrophilicity index. J.Am Chem

Soc 121(1999)1922–1924.

95. Ayers PW, Anderson JSM, Rodriguez JI, Jawed Z Indices for predicting

the quality of leaving groups. Phys.Chem.Chem.Phys 7 (2005)

1918–1925.


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