Organic single crystals of 2-picolinictrichloroacetate (PTCA) have been successfully grown by slow evaporation technique. The structural and optical characterization of the PTCA is analysed experimentally by Fouriertransform infrared and UV–visible spectroscopic technique and theoretical studies, by density functional theory method. The charge transfer interactions leading to nonlinear properties taking place in the molecule have been studied by highest energy occupied molecular orbital and lowest energy unoccupied molecular orbital analysis and natural bond orbital analysis. Open-aperture Z-scan results on evaluating the nonlinear optical properties experimentally, confirm these materials as good optical limiters. In addition, the PTCA exhibits a blue luminescence emission which shows that it is a potential material for OLED device applications.

The semi-organic nonlinear optical materials, L-histidinium trichloroacetate (LHTCA) single crystals are prepared by using solvent evaporation method. The prepared LHTCA crystal structures were analysed by X-ray examination.The UV–visible optical transparency of the grown crystal was accessed in the range of 200–1200 nm and it shows the LHTCA has high optical transparency in the UV region. From the Kurtz and Perry powder SHG method shows the NLO assets of the crystal, also laser damage threshold studies are analysed, and the grown crystals show the suitability for NLO applications. The quantum chemical computations have been carried out through DFT. It recognizes the geometricaland electronic structural properties, such as FMO, MEP and hyperpolarizability of the crystal and it suggests various intermolecular interactions especially hydrogen bonding. The various functional groups were analysed using FTIR andRaman spectra and the vibrational frequencies from experimental and theoretical values were evaluated. From the above analyses, the solution grown LHTCA crystal is suitable for NLO applications.