Spectroscopic, single crystal X-ray, Hirshfeld, in vitro and in silico biological evaluation of a new series of potent thiazole nucleus integrated with pyrazoline scaffolds

In the present study, the spectroscopic characterization of a new series of substituted thiazole linked pyrazoline scaffolds 4a-1 was performed. The formation of 4a-1 from the intermediate 3-(4-chlorophenyl)-5[4-(propan-2-yl)phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide 2 and substituted 2-bromo-1-phenylethanone 3a-1 was evidenced through the changes in FTIR, H-1 NMR, C-13 NMR, LCMS data. The X-ray diffraction studies revealed that compound 2 and 4g crystallized in monoclinic crystal system with P2(1)/n space group. Compound 4j crystallized in triclinic system, PI space group with Z = 4. The percentage of intermolecular contacts and distribution of electrostatic potential of molecular crystal structures was resolved by Hirshfeld surface analysis with 2D finger plots and electrostatic potential map. The newly synthesized derivatives were screened for their in vitro antioxidant and antimicrobial activity. The single crystal studies revealed that, for compounds 2, 4g and 4j the isopropyl phenyl ring is positioned at near right angle with the other rings. Due to the lack of planarity of bulkier group substituted to phenyl ring (ring B), all the synthesized molecules showed weak to moderate radical scavenging capacity owing to the destabilization of the radical formed during oxidation. Also, on performing molecular docking studies to explore the interactions of ligand with the target pyrimidine nucleoside hydrolase YbeK with bound ribose complex (PNH, PDB ID-3GHW), disclosed that active compounds emerged for in vitro studies also bound to PNH more efficiently. The compounds with polar group substitution interacted through hydrogen bonding while other molecules with non-covalent interactions. (C) 2016 Elsevier B.V. All rights reserved.