R. Thirumurugan

Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: an organic NLO crystal.

8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P2(1). FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV-vis-NIR transmission spectrum shows the cutoff wavelength around 357 nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145°C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

Synthesis, crystal growth and physiochemical characterization of organic NLO crystal: L-ornithinium dipicrate (LODP).

L-ornithinium dipicrate (LODP) has been synthesized and good quality single crystals were grown by slow evaporation method at room temperature. Single crystal XRD confirms that the grown crystal belongs to the monoclinic system with the noncentrosymmetric space group P21. Powder X-ray diffraction study confirms the crystalline nature of the compound. FTIR spectral analysis confirms the functional group in the synthesized compound. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. The optical absorption spectrum shows the absence of absorption between 475 nm and 800 nm. The dielectric measurements were carried out to estimate the dielectric parameters of the grown crystal in the frequency range from 50 Hz to 5 MHz at various temperatures. The second harmonic property has been investigated by Kurtz-Perry powder technique. The relative SHG efficiency of LODP is found to be 14.57 times greater than that of the reference material KDP.