Growth and characterization of semiorganic crystal

Single crystals of urea thiourea sodium chloride (UTNC) were grown from aqueous solution by slow evaporation technique. FTIR spectra were recorded to identify the functional groups. The crystals were characterized by recording the powder X-ray diffraction that revealed the crystalline nature of the crystal. The UV?CVis spectral study was carried out to test the optical transmitting property. The second harmonic generation test (SHG) was carried out, and it shows the non-linear nature of the crystal. The thermal stability of the crystal was analyzed by thermogravimetric and differential thermal analysis (TG-DTA).     

Crystal growth and vibrational spectroscopic studies of the semiorganic non-linear optical crystal--bisthiourea zinc chloride

The semiorganic non-linear optical crystal bisthiourea zinc chloride (BTZC) was grown by mixed solvent slow evaporation technique. The solubilities under various solvents in different proportions have been studied. Vibrational spectra were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands were also assigned and discussed. The optical transmission spectral study was also carried out. The property of second harmonic generation of BTZC was also verified.     

EPR of gamma-irradiated single crystals of 2-amino-5-nitro pyridinium L-tartrate: a NLO material

Single crystals of a non-linear optical (NLO) material 2-amino-5-nitropyridinum L-tartrate (ANPLT) were grown by solvent evaporation technique and characterized by the measurement of density, FT-IR, FT-Raman and X-ray diffraction techniques. Microhardness study and SHG test were also carried out. The EPR spectra were recorded for gamma-irradiated single crystal of ANPLT. The angular variation studies of the spectra were carried out and the principal values of g- and A-tensors were determined. The site symmetry of the radical formed is axial.     

Synthesis, spectroscopic characterizations and quantum chemical computational studies of (Z)-4-[(E)-(4-fluorophenyl)diazenyl]-6-[(3-hydroxypropylamino)methylene]-2-methoxycyclohexa-2,4-dienone

In this study, the molecular structure and spectroscopic properties of the title compound were characterized by X-ray diffraction, FT-IR and UV-vis spectroscopies. These properties were also investigated using DFT method. The most convenient conformation of title compound was firstly determined. The geometry optimizations in gas phase and solvent media were performed by DFT methods with B3LYP adding 6-31G(d) basis set. The differences between crystal and computational structures are due to crystal packing in which hydrogen bonds play an important role. UV-vis spectra were recorded in different organic solvents. The results show that title compound exists in both keto and enol forms in DMSO, EtOH but it tends to shift towards enol form in benzene. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for Transition State. The formation of both keto and enol forms in DMSO and EtOH is due to decrease in the activation energy. TD-DFT calculations starting from optimized geometry were carried out in both gas and solution phases to calculate excitation energies of the title compound. The non-linear optical properties were computed at the theory level and the title compound showed a good second order non-linear optical property. In addition, thermodynamic properties were obtained in the range of 100-500K.     

Growth of ninhydrin single crystal and its characterization

A novel organic nonlinear optical crystal ninhydrin having good optical quality was grown by solution technique using aqua solution. The quality of the crystal was also examined by high-resolution X-ray diffraction study. Solubility studies were made at different temperatures. Functional groups present in the grown material were identified from the vibrational frequencies of recorded FTIR spectrum. Transmittance of the crystal was recorded using the UV-vis-NIR spectrophotometer. From the thermal analysis it was observed that the material exhibits single sharp melting point. The fluorescence spectrum of ninhydrin was recorded. The Vicker's microhardness values were measured for the grown crystal. Second harmonic generation conversion efficiency estimated using Kurtz and Perry method is about five times that of KDP.     

Synthesis, growth and characterization of 4-bromo-4'chloro benzylidene aniline--a third order non linear optical material

The organic nonlinear optical material of 4-bromo-4'chloro benzylidene aniline (BCBA) was synthesized and single crystal of BCBA was grown from acetone solution by solvent evaporation method at room temperature. Its three dimensional structure was elucidated from single crystal X-ray diffraction analysis at 173 K. Synthesized compound of BCBA was subjected to FTIR and (1)H and (13)C NMR spectral analyses. The range and percentage of optical transmission of BCBA was determined by UV-vis-NIR spectrum and its fluorescence spectrum was recorded using spectrofluorometer. The mechanical strength of the crystal was estimated using Vickers microhardness test on the (001) plane. Dielectric constant of the grown crystal was measured for various frequencies along (001) plane. The third order nonlinear optical properties of BCBA were investigated by Z-scan technique with He-Ne laser radiation of wavelength at 632.8 nm and the corresponding nonlinear refractive index, absorption coefficient and optical susceptibility were calculated.     

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.     

聚合物分散液晶(PDLC)材料的光聚合反应

以Ar+激光器为光源, 采用虎红、 N-苯基甘氨酸、二季戊四醇羟基五丙烯酸酯和乙烯基吡咯烷酮分别作为光引发剂、共引发剂、预聚物和稀释剂, 与液晶材料TEB30A结合, 通过光聚合反应, 制备了聚合物分散液晶(PDLC), 用紫外光谱和荧光光谱对其反应机理进行了分析. 实验结果表明, PDLC是通过光引发剂吸收光子能量后与共引发剂相互作用, 形成自由基中间体并引发聚合反应, 使预聚物与液晶产生相分离形成的.     

FTIR, FT Raman and thermal studies of bisthiourea manganese chloride--an organo metallic crystal

The organometallic crystal bisthiourea manganese chloride (BTMC) was grown by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectra were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands were also assigned and discussed. The optical transmission spectral study revealed the transmitting ability of the crystal in the entire visible region. The TGA/DTA analysis explains the thermal stability of the investigated crystal.     

Growth and studies of thiourea urea magnesium chloride (TUMC) single crystals

A new semi organic Non-linear optical (NLO) crystal thiourea urea magnesium chloride (TUMC) was grown by slow evaporation technique at room temperature. Good quality single crystals were grown within 20?days. The FTIR spectrum of title compound was recorded and vibrational assignments were made. The recorded UV?Cvis spectrum shows the optical transmission property of the crystal. The Second harmonic generation (SHG) of TUMC crystal was tested by Kurtz?CPerry method using Nd:YAG laser and the result confirms that the grown crystal exhibits NLO property. To analyse the thermal stability of the crystal TG/DTA analysis were made. Detailed structural analysis of the compound is under progress.     

含金属高聚物材料

综述含金属高聚物及其复合材料的制备方法，并简介这些材料所具有的导电，液晶，非线性光学等特殊性能及其应用前景。     

Polarised Raman and infrared spectral analysis of L-alanine oxalate (C5H9NO6)--a non-linear optical single crystal

L-alanine oxalate (C5H9NO6), a promising material for effective frequency conversion, was grown by standard slow evaporation technique. Solubility studies were carried out at different temperatures. Unambiguous assignments of fundamental modes of various molecular groups were made from the recorded infrared and polarised Raman spectra. The non-linear optical property has been confirmed from the optical transmission and fluorescence spectra.     

The growth and characterization of a metal organic crystal, potassium thiourea thiocyanide

The growth and characterization of a new non-linear organometallic crystal, potassium thiourea thiocyanide (PTT) is reported. The growth of single crystals was accomplished by the slow evaporation solution growth method. The grown crystals were characterized by XRD, TG–DTA, UV, and FTIR spectral analyses. PTT has good optical transmission in the entire visible region which is an essential requirement for a non-linear crystal. TG curve of PTT undergoes complete decomposition between 176 and 1,000 °C in three steps with corresponding three DTA peaks. The high thermal stability of organometallic crystals are due to strong bonding existing between the conjugation layers of thiourea molecule and the potassium ions.     

Stress-optical properties of bimodal polymer networks

The optical properties of bimodal poly(dimethylsiloxane) (PDMS) networks were studied with special emphasis on the non-linear stress optical properties exhibited by these materials. In particular the effect of chain length, and junction functionality on the strain induced birefringence was investigated. It is shown that for the non-linear properties to clearly manifest themselves a critical concentration of short chains is essential and that the junctions are tetra-functional. However, all bimodal compositions studied were found to exhibit a non-linear variation of birefringence with strain irrespective of the junction functionality. The optical properties of the unimodal networks were found to vary linearly with stress and strain as expected. The transition from non-linear to linear optical behavior on increasing the molecular weight of the short chains is also established.     

非线性光学材料──水草酸铵

一水草酸铵（简称ＡＯＭ）是一种优良的电光晶体￣［１］。文献￣［１，２］报道了该晶体的晶体结构，化学式为（ＮＨ＿４）＿２Ｃ＿２Ｏ＿２·Ｈ＿２Ｏ，属正交晶系，Ｐ２２２空间群，晶胞参数ａ＝０．８０３５ｎｍ，ｂ＝１。０３１ｎｍ，ｃ＝０．３８０１ｎｍ，ｚ＝２。本文拟报道ＡＯＭ单晶生长，热化学分析，透过波段以及非线性光学性质的初步研究。     

Biaxial smectic phases in non-linear optical properties and phase behaviour of an oxdiazole liquid crystal

A symmetric, low-molecular-mass liquid crystal based on the oxadiazole ring was synthesized and characterized. The symmetric position of the heterocyclic group in the centre of the liquid crystal, bis(4-hexyloxyphenyl)4,4-(1,3,4-oxadiazole-2,5-diyl)dicarboxylate, yields a very rigid and non-linear mesogenic core. Despite this non-linear structure, a broad liquid crystalline range with a smectic C and a smectic A phase was found. Conoscopic experiments on freely suspended films revealed the existence of two optical axes in the smectic A phase, indicating a phase symmetry anticipated for either a 'McMillan' biaxial smectic phase or a biaxial (achiral) ferroelectric smectic phase.     

Synthesis, growth and characterization of a new nonlinear optical material: 4-phenylpyridinium hydrogen squarate (4PHS)

A novel organic non-linear optical organic single crystal of 4-phenylpyridinium hydrogen squarate (4PHS) has been synthesized and successfully grown from aqueous solutions by slow evaporation solution growth method. In the present investigation the title compound has been synthesized by taking equimolar quantity of 4-phenylpyridine and squaric acid and mixed thoroughly using double distilled water as the solvent. The prepared concentrated solution was placed in an undisturbed condition, and then the solution was periodically inspected. The good quality single crystals have been harvested in a time span of 3 weeks. Then the grown crystal was characterized as single crystal XRD, differential thermal analysis, thermogravimetric analysis, FTIR, UV-vis-NIR, SHG, (1)H NMR and (13)C NMR analyses, respectively. The observed results from the characterization analyses show its suitability for NLO applications when compared with some of the existing organic crystals. The relative second harmonic generation of this grown crystal was found to be five times higher than that of KDP crystal. The UV cut-off wavelength and decomposition temperature of this grown crystal were also comparatively better. (1)H NMR and (13)C NMR spectroscopic studies were employed to elucidate the structure of the grown specimen.     

Structure and Nonliear Optical Properties of a Fluoroalkyl Chain Containing Biphenylester Liquid Crystal Molecules

Density functional theory and finite field FF method were employed to investigate the fluoroalkyl chain containing biphenylester liquid crystal molecules,and the results showed that the lowest-energy excitation was obtained from HOMO to LUMO with π→π* transition,and the absorption wavelength was obtained at around 390 nm,belonging to the near UV absorption area.It is found that the title compound molecules display good nonlinear optical properties,and the values of the second-and third-non-linear optical properties are 35 × 10-30 and 32 × 10-35 esu,respectively.     

Growth and characterization of cinnamic acid–urea single crystal

A single crystal of cinnamic acid–urea was grown by slow evaporation of methanol solution at room temperature. In this research, many analytical methods such as FTIR, second harmonic generation, NMR, and TG–DTA were used. The presence of title compound in the crystal lattice has been qualitatively determined by FTIR analysis. Thermal stability of the grown crystals was evaluated by TG-DTA. Incorporation of urea increases the thermal stability insuring the suitability of material for possible non-linear optical application up to 180 °C.     

Vibrational spectra and non linear optical proprieties of L-histidine oxalate: DFT studies

This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a nonlinear optical material L-histidine oxalate. Due to the lack of sufficiently precise information on geometric structure in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of L-histidine oxalate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2(1)2(1)2(1) of orthorhombic system. The FT-IR and Raman spectra of L-histidine oxalate were recorded and analyzed. The vibrational wave numbers were examined theoretical with the aid of Gaussian98 package of programs using the DFT//B3LYP/6-31G(d) level of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied compound. The geometrical parameters of the title compound are in agreement with the values of similar structures. To investigate microscopic second order non-linear optical NLO behaviour of the examined complex, the electric dipole μ(tot), the polarizability α(tot) and the hyperpolarizability β(tot) were computed using DFT//B3LYP/6-31G(d) method. According to our calculation, the title compound exhibits non-zero β(tot) value revealing microscopic second order NLO behaviour.