Synthesis growth characterization and theoretical studies of novel organic crystals in the isoniazid and pyrazinamide systems

Abstract

New organic cocrystals of isoniazid and pyrazinamide have been prepared using one-pot slow evaporation method. These cocrystals have been characterized extensively to understand the structural, functional, physical and chemical properties. Density functional theoretical analysis has been carried out to further characterize these compounds and corroborate the results obtained from single crystal x-ray diffraction studies. The non-linear optical and the dielectric properties of the cocrystals have been determined to find its applicability in opto-electronic devices. newlineThe cocrystal Pyridinium-4-carbohydrazide (2R,3R)-2,3- newlinedihydroxybutanedioate (PCDHB), crystallizes in the non-centrosymmetric orthorhombic space group P212121 with lattice parameters of a = 7.8791(5) A, b = 15.163(1) A, c = 19.8952(13) A. PCDHB has been further characterized by FTIR and powder X- ray diffraction studies. The dielectric and thermal studies as well as the UV-Vis-NIR spectral studies have been carried out. The optical band gap has been estimated to be 3.0 eV. Thermal analysis revealed that the cocrystal is stable up to a temperature of 162.7°C. The cocrystal shows 86% transparency in the entire visible and UV- Vis region with a lower cut-off wavelength of 310 nm. The cocrystal exhibits a second harmonic generation efficiency which is 2.23 times higher than the commercial KDP crystal. DFT studies have been carried out on the optimized crystal structure which revealed a wide network of intermolecular hydrogen bonding. Natural bond orbital analysis, Mulliken atomic charges studies have also been carried out to understand the electronic transitions, charge distribution and the stability of the cocrystal. newlinePyridine-4-carbohydrazide bis (4-hydroxynitrobenzene) (PCBHNB) has been synthesized and single crystals grown via one-pot slow evaporation method. The structure of the new cocrystal was determined by single crystal x-ray diffraction studies.