Gamma Glycine Research Articles

Solution growth of γ-glycine from cadmium sulphate as solvent for frequency doubling applications

Monocrystal nonlinear optical material γ-glycine was synthesized from glycine and cadmium sulphate in 3:1 mol ratio at ambient temperature by using the slow solvent evaporation experiment. Monocrystal γ-glycine crystallized in trigonal crystal structure with non-centrosymmetric space group P32. The signature peak of γ-glycine was confirmed by x-ray powder diffraction examination. Chemical shift and Infrared studies exhibited the presence of chemical group species, resonance signal chemical shifts and functional groups present in the gamma glycine powdered samples. The existence of cadmium Cd element concentration in gamma glycine solution was quantified by inductively coupled plasma optical emission spectrometry (ICP-OES) instrument. Optical information and other parameters of γ-glycine such as crystal transparency, energy band gap, refractive index, electrical susceptibility, extinction coefficient, optical conductivity, electrical conductivity, optical reflectance, transmittance and absorbance was determined using UV–visible-NIR spectrophotometer. Thermal information such as weight-loss profile, thermal stability, decomposition temperature point, melting point and phase transition temperature were determined from TG-DTG and TG-DSC thermograms. The improved phase transition temperature in the TG-DSC thermogram established that suitability of the grown γ-glycine crystal for optoelectronic device fabrication applications. Green colour fluorescence emission was emitted from the crystal. The existence of frequency doubling in the grown γ-glycine crystal was examined.

Selective crystallization of gamma glycine for NLO applications using magnesium sulfate (MgSO4) as an additive

Abstract Crystallization of γ-glycine in the presence of selected concentration (9 g/mL) of tailor-made additive magnesium sulfate heptahydrate salt (MgSO4·7H2O) has been studied at ambient temperature by adopting slow solvent evaporation procedure. The morphological modifications of glycine crystals grown from pure aqueous solutions of glycine and from glycine solutions containing magnesium species in the amount of 0.1 g/mL to 16 g/mL have been investigated thoroughly. The crystalline nature and phase identification of the crystalline material were confirmed by X-ray powder diffraction and SXRD studies. NMR studies revealed the information about the molecular conformation in solution, phase changes, functional groups and chemical environment. FT-IR spectra revealed distinct difference between α and γ-glycine polymorphs in the region around 880 cm−1 to 930 cm−1. The grown γ-glycine crystal had a lower cut-off value at 200 nm and the bandgap value evaluated from the Tauc plot was found to be 5.83 eV. The marked differences between α and γ-polymorphs of glycine were also revealed by DSC thermograms. The mechanical strength of the γ-glycine crystal was studied with the help of Vickers microhardness instrument. Kurtz-powder NLO study proved the generation of second harmonics (i.e. green light emission) in the grown γ-glycine crystal and its efficiency was calculated as 1.44 times better than that of the reference material potassium dihydrogen phosphate.

Gamma glycine crystal for efficient second harmonic generation of 1064 nm Nd:YAG laser light

The organic crystals with abundance of donor-acceptor moieties readily facilitate the mechanism of charge transfer which aids for grooming the nonlinear optical (NLO) effects and hence core investigation on glycine crystal is deliberately needed for visualizing its compatibility for frequency conversion device applications. In this communication the gamma glycine (GG) crystal has been firstly grown in presence of salicylic acid and priority is given to explore its optical properties. The structural parameters and space group of GG crystal has been confirmed by single crystal X-ray diffraction analysis. The qualitative analysis of GG crystal has been performed by means of fourier transform infrared spectroscopy. The color centered luminescence emission profile of GG crystal has been assessed by means of photoluminescence study. The UV–visible spectral analysis has been employed within 200–1100 nm to examine the optical transparency of GG crystal. The linear optical parameters of GG crystal has been evaluated using the transmittance data. The large enhancement in second harmonic generation (SHG) efficiency of GG crystal with reference to KDP and ADP crystal has been confirmed by Kurtz-Perry test. The competency of GG crystal for NLO device application has been proposed in vision of obtained results.

Crystallization, habit modification and control of nucleation of glycine polymorphs from aqueous solutions doped with magnesium sulfate impurity

Abstract The influence of magnesium sulfate as an additive in the nucleation of α and γ-polymorphs of glycine crystallized from aqueous solutions has been explored for the first time. Based on crystallization experiments, it was concluded that lower concentration of magnesium sulfate, say less than 2 g/mL, favors α-nucleation sites, whereas the optimized concentration of magnesium sulfate impurity to yield -nucleation sites is 2 g/mL and above. The nucleation time span (in days), solubility and pH were measured for α- and γ-nucleation sites in the aqueous solutions doped with magnesium sulfate. The glycine polymorphs α- and γ-single crystals were grown by slow solvent evaporation technique at ambient temperature. Crystal habit of glycine polymorphs was investigated and analyzed using goniometry. The unit cell dimensions and space group of the as-grown crystal were identified by single crystal XRD analysis. Both α- and γ-polymorphs of glycine were characterized structurally by powder XRD studies. The percentage of magnesium present in the grown glycine crystals was estimated by inductively coupled plasma optical emission spectrometry elemental analysis (ICP-OES). The nonlinear optical properties of the γ-glycine crystals were examined by Q-switched high energy Nd:YAG laser. The second harmonic generation output efficiency of the as-grown gamma glycine single crystals was computed to be 1.31 times superior than that of the reference material potassium dihydrogen phosphate (KDP).

Growth and characterization of nonlinear optical crystal Gamma glycine by the additive of lithium bromide

Single crystal of γ-glycine, a polymorphic form of glycine, was grown by slow solvent evaporation technique by the additive of lithium bromide. It was grown from the aqueous solution of glycine and lithium bromide in 2:1 M ratio respectively at room temperature. Good quality of γ-glycine single crystals was harvested up to the dimension of 25 × 22 × 20 mm3. In order to reveal its properties, the grown single crystals were subjected to various characterizations. Powder X-ray diffraction of the grown crystal was recorded and indexed. The unit cell parameters of the crystals were estimated by single crystal x-ray diffraction and they were compared with the literature values. The identification of the functional groups and hence the compound present in the crystalline sample by FTIR analysis confirms the polymorphic form of glycine. Optical transmittance studies were carried out by UV–Vis-NIR transmission spectrum in the range of 200–1100 nm wavelength. The powdered sample of the crystal was subjected to Kurtz Perry powder technique to find the coefficient of Second harmonic generation. The second harmonic generation (SHG) conversion efficiency of γ-glycine crystal is more than twice when compared with KDP crystal. The grown γ-glycine crystal was further characterized by Thermo gravimetric analysis (TGA) and Differential thermal analysis, to find its thermal stability and decomposition temperature. Dielectric constant and Dielectric loss were determined at different frequencies with respect to various temperatures. The mechanical properties such as microhardness and yield strength were evaluated by Vicker’s microhardness tester.

Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30–50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10−6 Sm−1 at 353K and 1.46 × 10−6 Sm−1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

Control of piezoelectricity in amino acids by supramolecular packing.

Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V-1, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V-1) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN-1, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.

Synthesis and characterization of γ-glycine – a nonlinear optical single crystal for optoelectronic and photonic applications

Abstract A single crystal of gamma-glycine (GG), a polymorph of glycine, was synthesized by crystallization. The single crystal of GG was grown from an aqueous solution. The morphology of GG was studied in order to assess its growth facets. The good quality single crystals were subjected to X-ray diffraction studies to reveal their structure. The FT-IR spectral analysis was carried out to confirm the presence of expected functional groups. The UV-Vis analysis was done for GG single crystals to determine the optical transparency and band gap. Simultaneous TG-DTA analysis was employed to understand the thermal and physicochemical stability of the title compound. The mechanical stability and laser stability of GG single crystal were studied using Vickers microhardness test and laser induced damage threshold on different planes of the crystal to reveal its anisotropic nature. The dielectric measurement was carried out as a function of frequency and the results were discussed. The existence of second harmonic generation (SHG) of the title compound was confirmed by Kurtz-Perry powder technique. The SHG effective nonlinearity and particle size dependence of GG powder sample were compared with a standard reference material: potassium dihydrogen phosphate (KDP).

Studies Of Gamma Glycine Crystlas Grown In The Aqueous Solution Of Zinc Chloride

Solution method was adopted to grow single crystals of gamma glycine from the aqueous solution of zinc chloride (GGZC). The harvested crystals were observed to be colourless, transparent and non-hygroscopic. The solubility studies were carried out by gravimetrical method at different temperatures and nucleation kinetic studies were done on the sample to understand the nucleation phenomena. The grown crystals were characterized by various studies like XRD studies, optical studies, dielectric studies, microhardness studies, LDT studies, SHG studies and measurement of density etc and the obtained results were analyzed and discussed. The results show that the grown GGZC crystal emits green laser light when the infrared laser light from Nd:YAG laser is passed onto the crystal. The grown GGZC crystal is found to be transparent in the visible region and it has high optical band gap.

Effect of ammonium acetate addition on crystal growth, spectral, thermal and optical properties of glycine single crystals

Gamma glycine single crystal is a potential organic nonlinear optical (NLO) material. It has been grown from a mixture of aqueous solutions of glycine and ammonium acetate by slow evaporation solution growth technique at room temperature for the first time. Powder X-ray diffraction studies are carried out and the results are compared. CHN analysis confirms the non-inclusion of ammonium acetate species in to the solution. FTIR studies are performed to identify the presence of various functional groups in the grown crystal. Differential scanning calorimetry analysis (DSC) was carried out to study the thermal stability and phase transition of the grown crystal. The optical analysis shows that UV cut-off of γ-glycine is at 190nm and it has a wide transparency window. The second harmonic generation relative efficiency of the grown crystals was observed to be 1.72 times that of potassium dihydrogen orthophosphate (KDP).

Structural, dielectric and piezoelectric properties of nonlinear optical γ-glycine single crystals

Gamma glycine was synthesized and the single crystals were grown by the slow evaporation method in the presence of lithium nitrate. Structure and crystalline nature of the grown γ-glycine crystal was confirmed by X-ray diffraction technique. It was found to crystallize in the trigonal system with space group P31. The chemical composition was determined by NMR. Fourier transform infrared studies revealed the functional groups present in the grown crystal and UV–vis–NIR spectra revealed the transmission properties of the crystal specimen. Surface morphology of the grown crystal was studied by scanning electron microscopy (SEM) and elemental composition was confirmed by energy-dispersive spectrometry (EDS). The second-order nonlinear optical property of the material was investigated by Kurtz powder technique and the relative second harmonic efficiency of γ-glycine was estimated to be higher than that of KDP. The dielectric measurement was carried out as a function of frequencies at room temperature and the results were discussed. The samples have shown piezoelectric behavior with a fairly good piezoelectric charge coefficient (d33) of 7.37pC/N. Photoluminescence studies showed emission peak around 350nm. Thermo gravimetric and differential thermal analyses were employed to understand the thermal and physio-chemical stability of the synthesized compound.

Growth and Characterization of Gamma Glycine Single Crystals Grown from Alpha Glycine in the Presence of Sodium Acetate

A nonlinear optical crystal of gamma glycine was grown by slow evaporation solution growth technique using deionized water and sodium acetate. The functional groups and vibrational frequencies were identified using FTIR spectral analysis. The cell parameters were determined from single crystal X-ray diffraction analysis. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. The optical transmittance window and lower cutoff wavelength have been identified by UV-absorption spectrum analysis. Second harmonic generation (SHG) efficiency measurement was carried out by powder Kurtz method.

Growth of gamma glycine crystal and its characterisation

Single crystal of gamma-glycine, an organic nonlinear optical material, has been grown by solvent evaporation technique from a mixture of aqueous solutions of glycine and potassium nitrate, lithium nitrate at room temperature. Gamma glycine crystals have been grown up to the dimension of 20mmx15mmx12mm. Powder X-ray diffraction of the grown crystal was recorded and indexed. Single crystal X-ray diffraction studies were carried out and the unit cell parameters were compared with the literature values. The gamma-phase of glycine is confirmed by single crystal XRD and FTIR spectral analysis. The crystals were characterised by UV-vis-NIR transmission spectrum in the range 200-1100nm. The second harmonic generation conversion efficiency of gamma-glycine crystal was twice the efficiency of KDP crystal. Thermal characteristics of gamma-glycine crystals were determined by thermogravimetric analysis (TGA) and differential thermal analysis, which shows the thermal stability of the grown crystals. Dielectric constant and dielectric loss measurements were carried out at different temperatures and frequencies. The microhardness of the grown crystals has been studied using Vicker's microhardness tester.

Comment on the paper by M. Lenin, G. Bhavannarayana, P. Ramasamy “Synthesis, growth, and characterization of a non-linear optical crystal – glycine lithium chloride” Opt. Commun. 282 (2009) 1202

We argue that the “glycine lithium chloride” crystal grown and characterized in the title paper actually is gamma glycine.

Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV–vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications.

Measuring Free-Energy Difference between Crystal Polymorphs through Eutectic Melting

We describe a method to measure the free-energy difference, DeltaG, between crystal polymorphs from their calorimetric data of eutectic melting with a common additive. The use of different additives yields DeltaG as a function of temperature. The method is suitable for crystals that chemically decompose or physically transform before melting. It applies to not only true polymorphs but also pairs of racemate and conglomerate of resolvable enantiomers. We illustrate the method with the polymorphs of glycine, d-mannitol, and tazofelone and report a new value (123 degrees C) for the enantiotropic transition temperature of alpha and gamma glycine. We show how different additives (including a liquid additive, water) can be used for different compounds. The DeltaG data thus obtained are important for structure-stability studies and controlling crystallization in polymorphic systems.

A scaled quantum mechanical force field and vibrational analysis for the gamma glycine crystal polymorph: Hydrogen bond stretching modes observed

A scaled quantum mechanical force field has been obtained from periodic solid state density functional theory calculations on the glycine crystal γ polymorph unit cell at the DNP/GGA/PBE level. The assignments here differ in some respects from those obtained earlier, primarily where a broad weak band observed in both Raman and IR spectra at 285 cm −1, previously assigned to an overtone of a lattice mode, is assigned here as a mix of Hydrogen bond stretching and CC torsion. The standard deviation of the error between experimentally observed and calculated frequencies, for calculations performed on both the optimized and neutron diffraction crystal structures, is 6 cm −1 for a total of 118 vibrational modes.

Postnatal development of GABA- and glycine-like immunoreactivity in the cochlear nucleus of the Mongolian gerbil (Meriones unguiculatus).

The maturation of the morphological substrate for inhibitory interactions was investigated in the cochlear nucleus of the gerbil with immunocytochemistry for gamma aminobutyric acid (GABA) and glycine on alternating vibratome sections. The patterns of immunostaining obtained with both antibodies in the adult closely conformed to the general mammalian scheme. Qualitative analyses revealed an age-related increase in staining intensity and in the relative numbers of immunolabelled cells after birth up to the age of 3-4 weeks. As early as birth and in all subdivisions of the cochlear nucleus, a few labelled cells and puncta in the sections were stained either with the GABA or the glycine antibody. Immunoreactive puncta and cells were, however, far less abundant than in the adult, and the staining intensity of cells was only weak. The most strikingly GABA-immunolabelled cells at birth were the Golgi cells of the granule-cell domains. The numbers of weakly GABA- and glycine-immunostained cells of the dorsal cochlear nucleus clearly increased between birth and the third postnatal week. At approximately the onset of hearing (postnatal day 12-14), some cells of the dorsal cochlear nucleus and small cells of the ventral cochlear nucleus gained adult-like GABA-staining properties. Almost adult-like labelling intensity was observed in glycine-immunoreactive cells of the deep dorsal cochlear nucleus and in some small cells of the ventral cochlear nucleus. Puncta staining to both antibodies appeared adult-like throughout the cochlear nucleus. About 2 weeks after the onset of hearing (at the latest), adult-like staining of all subsets of immunoreactive cells occurred throughout the cochlear nucleus in all specimens.

Delayed decrease of excitatory amino acid neurotransmitters in parietotemporal cortex and hippocampus after complete cerebral ischemia in aged rats

A 15-min period of complete cerebral ischemia (CCI) was used in aged rats to investigate changes in tissue contents of the amino acid neurotransmitters (AANT) glutamate (glu), aspartate (asp), gamma aminobutyric acid (gaba) and glycine (gly) in parietotemporal cortex and hippocampus during ischemia and up to 96 h of postischemic recirculation. The AANT were determined by HPLC. The excitatory AANT glu and asp showed a first decrease at the end of CCI in hippocampus and after 1 h of postischemic recirculation in parietotemporal cortex, reflecting a release of these AANT into the extracellular space with a further loss into the blood. A second decrease in glu and asp was seen after 24 h of postischemic recirculation in hippocampus and after 48 h in parietotemporal cortex. This coincides with previously described disturbances in energy metabolism from 24 h to 96 h in hippocampus and from 48 h to 72 h in parietotemporal cortex in the same experimental model in aged rats. This might be a causal factor in delayed postischemic neuronal damage. A comparison with investigations in young animals reveals an enhanced decrease of glutamate and aspartate tissue contents during the postischemic recirculation period in old rats indicating an enhanced release of these amino acid neurotransmitters. A significant decrease of gaba tissue content seen in hippocampus at 48 h and 72 h of postischemic recirculation with subsequent disproportion of inhibitory AANT (lower) to excitatory AANT (higher) might reflect a greater vulnerability of hippocampus than of parietotemporal cortex to ischemia. A significant decrease in the NMDA-receptor coactivator gly in parietotemporal cortex at the end of CCI and at 48 h, 72 h, and 96 h of postischemic recirculation, which was not seen in hippocampus, might be another reason for higher vulnerability of hippocampus to ischemia.

A possible role of AA2 excitatory amino acid receptors in the expression of stimulant drug effects

GDEE, an antagonist of the AA2 or quisqualic acid category of excitatory amino acid receptor, decreases behavioral activity and locomotor stimulation induced by cocaine and amphetamine when locally injected into the nucleus accumbens. The present experiment was intended to examine the effects of systemic GDEE and other excitatory amino acid antagonists on stimulant-induced locomotor activity. GDEE markedly attenuated the stimulant effect of amphetamine, and partially blocked the effects of phencyclidine (PCP). Apomorphine-induced cage climbing behavior was partially decreased by lower dosages of GDEE, but was almost completely blocked by the highest dosage tested. Amphetamine-induced stimulation of locomotor activity was not decreased by any of the other excitatory amino acid antagonists that were tested, including MK-801, 2-amino-7-phosphonoheptanoic acid (APH), or CNQX. APH decreased stereotypy only at a high dosage (250 mg/kg), which also produces ataxia. Several other compounds, including L-glutamic acid gamma ethyl ester (GMEE), L-glutamic acid, glycine, and L-glutamine did not block amphetamine-induced stimulation in molar dosages equivalent to the highest dosage of GDEE (8 mmol/kg). It is concluded that the AA2 excitatory amino acid receptor is important in the expression of activating effects of stimulant drugs.