Crystallization and Characterization of a New NonLinear Optical Crystal: L Proline Succinate (LPS)

doi:10.4236/jcpt.2012.21004

Paper Menu >>

Journal Menu >>

Journal of Crystallization Process and Technology, 2012, 2, 21-24

http://dx.doi.org/10.4236/jcpt.2012.21004 Published Online January 2012 (http://www.SciRP.org/journal/jcpt) 21

Crystallization and Characterization of a New Nonlinear

Optical Crystal: L-Proline Succinate (LPS)

P. Paramasivam1, C. Ramachandra Raja2*

1Anjalai Ammal Mahalingam Engineering College, Kovilvenni, India; 2Department of Physics, Govt Arts College (Autonomous),

Kumbakonam, India.

Email: *[email protected]

Received November 7th, 2011; revised December 9th, 2011; accepted December 18th, 2011

ABSTRACT

In this analysis, the single crystal of L-Proline Succinate (LPS) has been successfully synthesized and the purity of ma-

terial has been increased by repeated recrystallization process. Single crystal was grown by adopting the method of

growing in a slow evaporation solution using water as solvent at room temperature. The LPS single crystal has been

synthesized by taking equimolar quantity of L-Proline and succinic acid, by mixing them thoroughly using deionized

water. The prepared concentrated solution was placed in an undisturbed condition, and the solution was inspected regu-

larly. The single crystal has been harvested over a period of 1 month. The same crystal was characterized by different

techniques for finding its su itability fo r device fabrication s. Th e grown crystal was characterized by Single crystal XRD,

Powder XRD, FTIR, UV-vis-NIR, DTA/TGA and SHG analyses, respectively. The observed results from various char-

acterization show the suitability for NLO application. The second harmonic generation of this grown crystal was

checked using Kurtz Perry technique which showed po sitive results. The UV cut-o ff wavelength and the decompositio n

temperature of this grown crystal were found to be good when compared with the existing organ ic crystals.

Keywords: Slow Evaporation; Crystal Growth; X-Ray Diffraction; Fourier Transform Infrared Spectroscopy; Second

Harmonic Generat i on; LPS C rys t al

1. Introduction

One of the most important applications of NLO materials

is their use for fast data transfer, combined with a very high

Signal-to-Noise ratio, even over long distances. In recent

years, different applications of NLO and photorefractive

materials have been developed, for example, optical fre-

quency conversion, electro-optical modulation, dynamic

holography, optical writing and optical guiding of laser

beams [1]. It is seen that L-proline and (4R)-hydroxy-L-

proline derivatives, containing donor groups are chiral car-

ri ers [2]. The introduction of chirality by means of an asym-

metrically substituted carbon should in addition respect

the molecular features leading to a high nonlinear beha-

v iour [3]. Proline and its derivatives are often used as asym-

metric catalysts in organic reactions.

Only noncentrosymmetric alignment of the chromopho-

res in the crystal lattice leads to an observable bulk second-

order NLO response [4]. In order to obtain the adjustment

of the nonlinear efficiency/transparency, based on the mo-

lecular engineering and crystal engineering approach, it

is tried to develop a new method to design organic non-

linear optical second-harmonic generation materials such

as organic inclusion complex [5]. In this study, the crys-

tal growth of a new NLO crystal of L-Proline succinate by

slow evaporation technique and its characterization along

with its optical properties is reported.

2. Experimental Details

Equal proportions of L-Proline and succinic acid were ta-

ken and were dissolved separately in deioinized water. Then

the solution of L-Proline was poured into the dissolved suc-

cinic acid mixture. The so lution thus arrived was filtered

twice to remove dust particles and undissolved materials.

The reaction takes place between L-Proline and succinic

acid (acid-based) through hydrogen transfer. Thus formed

ionic compound of L-Proline succinate is represented in

the following equ ation:

The saturated solution was maintained in the undistur-

bed condition and the beaker was covered by polythene

paper. Few holes were made on the polythene cover for

slow evaporation. By adopting the solution growth method,

*Corresponding a uthor.

Crystallization and Characterization of a New Nonlinear Optical Crystal: L-Proline Succinate (LPS)

single crystal of L-Proline succinate (LPS) was grown from

supersaturated solution at room temperature. Then this so-

lution was periodically inspected and from the 20th day on-

wards the crystal started growing and it was permitted to

grow for another 10 days in order to get a nominal size sui-

table for ch aracterization. The single crystal of LPS with

dimensions of 8 mm × 5 mm × 10 mm was thus obtained.

The L-Proline interacts with succinic acid through a sin-

gle N-H-O hydrogen bond. A single crystal of LPS which

has been grown by this process is show n in Figure 1.

Characterization

The lattice parameters and the crystal systems have been

determined using single crystal X-ray diffraction analysis

(Model: Bruker AXS Kapp a APEX II single cr ystal CCD

diffractometer). The functional groups presented in the LPS

compound have been identified by Bruker IFS 66V model

FTIR Spectrometer using KBr pellet technique in the re-

gion 400 - 4000 cm–1. Optical behaviour of LPS was mea-

sured by Perkin Elmer Lambda 35 UV-VIS-NIR Spectro-

photometer in the wavelength range of 190 - 1100 nm. The

thermal stability of LPS was studied by thermo gravimet-

ric analysis (TGA) and differential thermal analysis (DTA)

by using SDT Q600 V8.3 Build 101 thermal analyzer in-

strument ranging from room temperature to 1100˚C at a

heatin g rate of 20˚C per minute under nitrogen atmosphere.

3. Results and Discussion

3.1. Single Crystal X-Ray Diffraction Analysis

Single crystal X-ray diffraction studies were carried out

on the grown crystals. The X-ray data were collected using

X-ray diffractometer (Model: Bruker AXS Kappa APEX

II single crystal CCD). The observed results indicate that

the crystal belongs to monoclinic crystal system and the

determined unit cell parameters are a = 5.07 Å, b = 8.84

Å, c = 5.48 Å, α = 90˚, β = 91.60˚, γ = 90˚ and V = 246 Å3.

3.2. FTIR Spectroscopy

The functional groups presented in the LPS compound

have been identified by Bruker IFS 66V model FTIR Spec-

trometer using KBr pellet technique in the region 400 -

40 00 cm–1. The FTIR spectrum of title compound is shown

in Figur e 2 . The peaks obtained are 3419 cm–1 , due to stret-

ching vibration of CH and the peak at 1600 cm–1 is due to

the stretching vibration of C=O. The bands appeared at

793 cm–1 is assigned unambiguously to the wagging of NH2

modes. The OH stretching vibrations is assigned in the

range of 2565 cm–1. The peak at 1398 cm–1 is due to the

symmetric stretching of COO–. These assignments are also

supported in the literature [6 -10]. The ob serv ed b ands along

with their vibrational assignments are given in Table 1.

Figure 1. Photograph of LPS crystal.

Figure 2. FTIR spectrum of LPS crystal.

Table 1. The observed frequencies and corresponding as-

signments.

Observed FTIR frequencies Assignments

3419 CH stretching

1600 C=O stretching

1398 Symmetric stretching of COO–

793 NH2 wagging

2565 O-H stretching

3.3. UV-Visible Spectroscopy

Good o ptical transmittance and lower cu t-off wavelengths

are very important properties for NLO cryst a ls. Opt i c al be-

haviour of LPS was measured by Perkin Elmer Lambda

35 UV-VIS-NIR spectrophotometer in the wavelength

range of 190 - 1100 nm. The recorded spectrum is shown

in Figure 3. The crystals are broadly transparent possess-

ing a transmission of greater than 90% for light with in-

cident wavelengths from 236 - 1100 nm. The UV trans-

parency cut-off wavelength of LPS crystal occurs at 204

nm which is better than L-Prolinium tartrate and 4-

phenylpridinium hydrogen squarate [11,12]. It is observ ed

Crystallization and Characterization of a New Nonlinear Optical Crystal: L-Proline Succinate (LPS) 23

Figure 3. Transmission spectrum of LPS crystal.

that in the LPS crystal, there is high transmittance in the

fa r u lt r av io l et , v isible and infra red reg ion. Hence, the title

compound may be used for the nonlinear optical applica-

tions in the above mentioned wavelength range.

3.4. Second Harmonic Generation

The SHG of the crystal was checked using the powder

SHG technique developed by Kurtz and Perry [13]. A Q-

switched Nd:YAG laser beam of wavelength 1064 nm,

wit h b e am energy of 4.5 mJ/pulse, and pulse width of 8 ns

with a repetition rate of 10 Hz were used. The grown single

crystal was crushed to fine powder and then packed in a

micro capillary of uniform bore and exposed to laser ra-

diations. The 532 nm radiation was collected by a mono-

chromater after separating the 1064 nm pump beam with

an infra-red blocking filter. The second harmonic radia-

tion generated by the randomly oriented micro crystals

was focused by a lens and detected by a photo multiplier

tube (Hamamatsu R2059). The second harmonic genera-

tion is confirmed by the emission of green light and its

efficiency is found t o be 23% of that of KDP crystal.

3.5. Thermal Analysis

The thermal behaviour of LPS had been studied by ther-

mo gravimetric analysis (TGA) and differential thermal

analysis (DTA) using SDT Q6 00 V8.3 Build 101 ther mal

analyzer instrument, ranging from room temperature to

1100˚C at a heating rate of 20˚C per minute under nitro-

gen atmosphere. TGA-DTA curve of L-Proline succinate

is shown in Figure 4. From the TGA curve, the material

starts to decompose around 160˚C, which is also confir-

med by the peak which appears at 154˚C in the DTA curve.

The ther mal stabil ity of LPS i s low compar ed to L-Pro line

(205˚C) and succinic acid (240˚C). The TGA curve shows

a major loss of weight and two losses of smaller weight.

The major weight loss of 86.58% is observed between

Figure 4. TGA/DTA curve of LPS crystal.

169.91˚C and 243.16˚C. The decomposition of L-Proline

su ccinate (87.53%) leads to th e major loss of weig ht in the

above mentioned temperature region. Further, a small loss

of weight of 10.24% is observed, which may be due to the

decomposition of C2H2 (11.16%). During the next stage

of decomposition, fraction amount of hydrogen may be

decomposed. A residue of 0.9018% which may be due to

presence of some fraction of carbon molecule is observed.

The thermal stability of the LPS single crystal is more than

glycine nitrate [14] and is lower than gamma glycine and

glycine acetamide [13,15].

4. Conclusion

We have synthesized a new non-linear optical crystal with

an interesting hydrogen bonding network that holds to-

gether the L-Proline and succinic acid molecules. The

grown crystals are characterized by different instrumen-

tal techniques. The single crystal XRD studies prove that

the grown LPS crystals belong to monoclinic crystal sys-

tem. The particle size of the grown crystal is character-

ized by Powder XRD ana lysis. The pr esence of th e func-

tional groups of the grown crystal has been confirmed by

FTIR analysis. From the optical transmittance spectrum,

it is observed that there is high transmittance in the far

u ltraviolet, vis ible and near infra red regions. The UV trans-

parency cut-off wavelength of LPS crystal occurs at 204

nm. The Kurtz Perry technique for second harmonic ge-

neration has showed positive r esults. It is well known that

the DTA and TGA studies reveal that the crystal is ther-

mally stable up to 160˚C.

5. Acknowledgements

The authors are thankful to Prof. P.K. Das, IISc, Banga-

lore, India for the SHG test. They also express their gra-

titude to the authorities of SAIF, IIT, Chennai, India and

CECRI, Karaikudi, India for providing spectral facilities,

Crystallization and Characterization of a New Nonlinear Optical Crystal: L-Proline Succinate (LPS)

to undertake this study.

REFERENCES

[1] T. M. Kolev, D. Y. Yancheva and S. I. Stoyanov, “Syn-

thesis and Spectral Elucidation of Some Pyridinium Be-

taines of Squaric Acid: Potential Materials for Nonlinear

Optical Applications,” Advanced Functional Materials,

Vol. 14, No. 8, 2004, pp. 799-805.

[2] B. Gutierrez, N. Rubio and C. Minguillon, “Evaluation of

L-Proline Derivatives as Chiral Carriers in the Separation

of Enantiomers by Membrane Techniques,” Journal of

Desalination, Vol. 200, No. 1-3, 2006, pp. 117-119.

[3] R. Hierle, J. Badan and J. Zyss, “Growth and Characteri-

zation of a New Material for Nonlinear Optics: Methy

l-3-Nitro-4-Pyridine-1-Oxide (POM),” Journal of Crystal

growth, Vol. 69, No. 2-3, 1984, pp. 545-554.

doi:10.1016/0022-0248(84)90366-X

[4] T. kolev, B. Stamboliyska and D. Yancheva, “Spectral

and Structural Study of Two Acceptor-Substituted Pyri-

dinium-Betaines of Squaric Acid: Promising Chromo-

phores for Nonlinear Optical App lications,” Chemical Phy-

sics, Vol. 324, No. 2-3, 2006, pp. 489-496.

doi:10.1016/j.chemphys.2005.11.014

[5] F. Q. Meng, M. K. Lu, J. Chen, S. J. Zhang and H. Zeng,

“Characterization of Linear and Nonlinear Optical Prop-

erties of a New Single Crystal,” Solid State Communica-

tions, Vol. 101, No. 12, 1997, pp. 925-928.

doi:10.1016/S0038-1098(96)00702-8

[6] K. V. Krishna and M. Arivazhagan, “Vibrational and Nor-

mal Coordinate Analysis of Xanthine and Hypoxanthine,”

Indian Journal of Pure & Applied Physics, Vol. 42, No.

12, 2004, pp. 411-418.

[7] G. Socrates, “Infrared and Raman Characteristic Group

Frequencies,” 3rd Edition, Wiley, Chichester, 2001.

[8] G. Varaasyi, “Assignments for Vibrational Spectra of

Seven Hundred Benzene Derivatives,” Wiley, New York,

1974.

[9] S. Gunasekaran and D. Uthra, “Fourier Transform Infra-

red and Fourier Transform Raman Spectra and Normal

Coordinate Analysis of Ethyleneimine,” Indian Journal of

Pure & Applied Physics, Vol. 46, No. 2, 2008, pp. 100-

105.

[10] S. Krishnan, C. J. Raj, R. Robert, A. Ramanand and S. J.

Das, “Growth and Charac terization of Succinic Acid Sin-

gle Crystals,” Crystal Research Technology, Vol. 42, No.

11, 2007, pp. 1087-1090. doi:10.1002/crat.200710981

[11] S. A. M. Britto Dhas and S. Natarajan, “Growth and Cha-

racterization of L-Prolinium Tartrate—A New Organic

NLO Material,” Crystal Research Technology, Vol. 42,

No. 5, 2007, pp. 471-476. doi:10.1002/crat.200610850

[12] C. R. Raja, P. Paramasivam and N. Vijayan, “Synthesis,

Growth and Characterization of a New Nonlinear Optical

Material: 4-Phenylpyridinium Hydrogen Squarate (4PHS),”

Spectrochimica Acta Part A, Vol. 69, No. 4, 2008, pp.

1146-1149. doi:10.1016/j.saa.2007.06.014

[13] V. Krishnakumar, L. G. Prasad, R. Nagalakshmi and P.

Muthusamy, “Ph ysicochemical Properties of Organic Non -

linear Optical Crystal for Frequency Doubling: Glycine

Acetamide,” Materials Letters, Vol. 63, No. 15, 2009, pp.

1255-1257. doi:10.1016/j.matlet.2009.02.052

[14] S. A. M. Britto Dhas and S. Natarajan, “Growth and

Characterization of a New Organic NLO Material: Gly-

cine Nitrate,” Optics Communications, Vol. 278, No. 2,

2007, pp. 434-438. doi:10.1016/j.optcom.2007.06.052

[15] T. Balakrishnan, R. R. Babu and K. Ramamurthi, “Grow-

th, Structural, Optical and Thermal Properties of γ-Gly-

cine Crystal,” Spectrochimica Acta Part A, Vol. 69, No. 4,

2008, pp. 1114-1118. doi:10.1016/j.saa.2007.06.025