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Journal of Crystal Growth 312 (2010) 301–304

Contents lists available at ScienceDirect

Journal of Crystal Growth

0022-02

doi:10.1

n Corr

E-m

journal homepage: www.elsevier.com/locate/jcrysgro

Growth and characterization of a nonlinear optical crystal 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)—benzaldehyde-imine

Shivani Singh n, Bansi Lal

Centre for Laser Technology, Indian Institute of Technology Kanpur, Kanpur 208016, India

a r t i c l e i n f o

Article history:

Received 30 September 2009

Received in revised form

7 October 2009

Accepted 18 October 2009

Communicated by M. Schieberexhibits second harmonic generation property.

Available online 23 October 2009

PACS:

42.70.Mp

78.40.�q

65.40.�b

61.66.Hq

81.10.Dn

Keywords:

A1.Characterization

A2.Growth from solutions

B1.Organic compounds

B2.Nonlinear optic materials

48/$ - see front matter & 2009 Elsevier B.V. A

016/j.jcrysgro.2009.10.037

esponding author. Tel.: +91 5122 597463; fa

ail address: shivani@iitk.ac.in (S. Singh).

a b s t r a c t

Organic nonlinear optical crystals of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine

has been successfully grown by low temperature solution growth technique. The grown crystals were

characterized by single crystal XRD, FTIR, TGA/DTA and UV–vis-NIR techniques. Nonlinear optical

property of the crystal was studied by Kurtz powder technique using Nd: YAG laser and the crystal

& 2009 Elsevier B.V. All rights reserved.

1. Introduction

Organic crystals with large order nonlinear optical (NLO)susceptibilities attract great interest because of their potentialapplication in second harmonic generation. Organic crystalsexhibit extremely large nonlinear optical response, in many casesorders of magnitude larger than the most inorganic materials.Now-a-days organic crystals are highly recognized as thematerials of the future because their molecular nature combinedwith versatility of synthetic chemistry can be used to alter theirstructure in order to maximize the nonlinear properties [1–6].Molecular organic compounds with one or more aromatic systemsin conjugated position leading to charge transfer systems havebeen intensely studied for the past two decades. These com-pounds must crystallize in noncentrosymmetric class for theapplication of quadratic nonlinear optical effects [7]. Thesubstituted benzyl derivatives with high optical nonlinearitiesare very promising materials for future optoelectronic andnonlinear optical applications.

ll rights reserved.

x: +91 5122 597766.

Here we report the growth of a promising nonlinear organicsingle crystal 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzal-dehyde-imine that is grown by low temperature solution growthtechnique. The crystals were characterized using powder X-raydiffraction and single crystal XRD, Fourier transform infrared (FT-IR) analysis, thermogravimetric analysis (TGA), differential ther-mal analysis (DTA) and UV–vis spectroscopy studies have beencarried out. The second-harmonic generation property of thecrystal has been tested.

2. Experimental procedure

2.1. Synthesis and crystal growth

2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-iminewas grown by low temperature solution growth technique.Commercially available 2-chlorobenzylamine (Lancaster 98%)2-hydroxy-3-methoxyaldehyde 99% (ACROS ORGANICS 99%) andethanol (99%) were used without further purification to synthe-size the compound. Fig. 1 gives a schematic flow chart forthe synthesis of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine crystals. The title compound was prepared

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Fig. 1. Flow chart illustrating the procedure for the preparation of 2-hydroxy-3-

methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine by low temperature solution

growth technique.

Fig. 2. Photograph of the as-grown single crystal of 2-hydroxy-3-methoxy-N-(2-

chloro-benzyl)-benzaldehyde-imine.

Fig. 3. Powder X-ray diffraction pattern of 2-hydroxy-3-methoxy-N-(2-chloro-

benzyl)-benzaldehyde-imine.

S. Singh, B. Lal / Journal of Crystal Growth 312 (2010) 301–304302

by the addition of 0.01 mol of 2-chlorobenzylamine in 50 ml ofhot ethanol to 0.01 mol of 2-hydroxy-3-methoxyaldehyde in75 ml boiling ethanol. This mixture is stirred for �3 h at 40 1C,followed by heating to reflux for �15 h at the same temperature.The temperature of the growth solution was controlled with anaccuracy of 70.01 1C by using a constant temperature bath. Thesingle crystal of good optical quality of size 9.75�3.18�7.18 mm3 was obtained as shown in Fig. 2.

3. Characterization studies

The grown crystals of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine were confirmed by single crystaland powder X-ray diffraction analysis. The functional groups wereidentified by Fourier transform infrared studies using Brukersvector 22 IR spectrometer in the range 4000–400 cm�1. Differ-ential thermal analysis (DTA) and thermogravimetric analysis(TGA) of the crystalline fibers were carried out using the instru-

ment Pyris diamond TG/DTA Analyzer (perkin), respectively, inthe temperature range of 50–400 1C at a heating rate of 10 1C/minin inert nitrogen atmosphere. The absorbance and transmittanceproperties of the crystal were analysed by using Shimadzu Model1601 spectrometer between range 250–1200 nm. The secondharmonic generation property of the grown crystal was using Nd:YAG laser. The detailed results are presented in the followingsections.

3.1. Single crystal and powder X-ray diffraction studies

The X-ray powder diffraction studies were carried out todemonstrate the crystallinity of title compound crystal using ISODEBYEFLEX 2000 diffractometer employing CuKa of 1.531841 Ain the range 101–501 with 20 mA and 30 kV.The powder X-rayspectrum is shown in Fig. 3. The as-grown crystals of the titlematerial have been subjected to single crystal XRD employing aBruker Smart Apex CCD diffractometer using M0 Ka(l=0.71073 A).The single crystal XRD study reveals that the titlematerial belongs to orthorhombic crystal system and space groupPbca the lattice parameters are a=7.068(6) A, b=13.727(8) A andc=27.600(9) A; a=89.88(3) A and b=g=90.14(6) A. Volume of thematerial is found to be 2678.0(3) A3. The crystallographic data ofthe crystal are compared with that of H. Unver et al.[8] and are inaccordance with the literature.

3.2. FT-IR analysis

The Fourier transform infrared (FT-IR) analysis of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)—benzaldehyde-imine was carriedout between 400–4000 cm�1.The spectrum is shown inFig. 4. Infrared spectroscopy is effectively used to identify thefunctional groups to determine the molecular structure of thesynthesized compounds. The various functional groups presentin the compound, 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)—benzaldehyde-imine was identified and chemical structure wasconfirmed by recording the IR spectrum. The characteristic IRabsorption bands observed are consistent with the functionalgroups present in the compound and the assigned values are asrecorded in Table 1.

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Fig. 4. FTIR spectra of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-

imine.

Table 1Observed spectral data and their assignment in 4000–400 cm-1 range.

IR (cm-1) Mode assignments

3448 m(O–H)3068 (mC–H.Ar–H)3006 CH2asymmetric stretching2917 CH3stretching2852 CH2symmetric stretching1633 C=N stretching1470 CH2asymmetric bending1444 C=C stretching1168 NH3

+rocking1045 C–O stretching971 C–Cl760 C–H stretch524 C–C=O in plane deformation

Fig. 5. UV–vis-NIR transmission spectra of 2-hydroxy-3-methoxy-N-(2-chloro-

benzyl)-benzaldehyde-imine.

Fig. 6. TGA/DTA curve of the sample.

S. Singh, B. Lal / Journal of Crystal Growth 312 (2010) 301–304 303

3.3. UV–vis-NIR spectral studies

To, determine the transmission range and hence to know thesuitability of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzal-dehyde-imine single crystals for optical applications, UV–vis-NIRanalysis was made in the wavelength range from 200 to 1000 nmusing Shimadzu Model 1601 spectro-photometer. The UV–visspectra were recorded for an ethanol solution of 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine in a quartzcell of 10 mm length. The plot of absorption vs wavelength (nm)is shown in Fig. 5. For optical application, especially for SHG, thecrystal must be transparent in the wavelength region of interest.It has a good transparency in between 540 and 1020 nm, thecutoff wavelength of the grown crystal is around 570 nm.

3.4. Kurtz powder SHG test

The first and the most widely used technique for confirmingthe SHG from prospective second order NLO materials is theKurtz-powder technique [9].The fundamental beam of 1064 nmfrom Q-switched Nd: YAG laser is used to test the secondharmonic generation property of the 2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-imine crystal by using Kurtz tech-nique. It was mounted on a crystal holder and IR radiation

(l=1064 nm) was inputted from a Nd: YAG laser with a pulseenergy of 400 mJ and a 8 ns pulse width. The beam was wellfocused before it was incident on the crystal. The second-harmonic green signal (l=532 nm) was generated by thematerial. A strong bright green emission emerging from themounted crystal shows that the sample exhibits good NLOproperty.

3.5. Thermal studies

The Thermal properties of the as-grown crystals were studiedusing a Pyris diamond TG/DTA Analyzer (perkin) with a heat rateof 10 1C/min in the nitrogen atmospheres. The results obtainedfrom TGA and DTA thermal studies are shown in Fig. 6. In the TGAtrace, there is a single major weight loss starting at 210 1C. Thematerial is moisture-free and is stable upto 200 1C. Thedecomposition completes at about 850 1C, leaving no residue.However, in the DTA trace an endothermic peak is clearly seen at87.5 1C, which corresponds to the melting point of the sample andthe same has been verified by us using the capillary melting pointapparatus (Table 2).

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Table 2Comparison of SHG efficiencies of promising organic NLO crystals.

Compound SHGefficiency

m-Nitroacetanilide 1.2

Benzophenone 1.9

3,4 Diaminobenzophenone 2.7

4-Bromo-2-methylanilline 3.2

2-hydroxy-3-methoxy-N-(2-chloro-benzyl)-benzaldehyde-

imine

4.3

S. Singh, B. Lal / Journal of Crystal Growth 312 (2010) 301–304304

4. Conclusion

2-hydroxy-3-methoxy-N-(2-chloro-benzyl) benzaldehydeimine single crystals are grown from ethanol solvents by thelow temperature solution growth technique. Transparent yellowsingle crystals of size 9.75�3.18�7.18 mm3 were obtained.Single crystal X-ray diffraction analysis was carried out to findcell parameters and volume of the system. The functional groupswere confirmed by FT-IR analysis. The thermal behavior of thecrystal has been confirmed by TGA analysis. The SHG in the growncrystals was confirmed by the emission of green radiation usingNd: YAG laser as the source. 2-hydroxy-3-methoxy-N-(2-chloro-benzyl) benzaldehyde imine crystal has good transparency range

with UV cutoff wavelength at 570 nm. With the presence of widetransparency range and higher second harmonic efficiency, the 2-hydroxy-3-methoxy-N-(2-chloro-benzyl) benzaldehyde iminecrystal may be used for NLO application.

Acknowledgements

Financial support provided to one of the authors, ShivaniSingh, by CSIR, New Delhi, India is gratefully acknowledged.

References

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[4] K. Kagawa, M. Sagawa, A. Kakuta, M. Saji, H. Nakayama, K. Ishii, J. Cryst.Growth 139 (1994) 309.

[5] S.X. Dou, D. Josse, J. Zyss, J. Opt. Soc. Am. B, vol. 10, pp. 1708.[6] N. Vijayan, R. Ramesh Babu, R. Gopalakrishnan, P. Ramasamy, W.T.A Harrison,

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