Crystal structure optimization, semi-empirical quantum chemical calculations and antibacterial activity of (4Z)-2-phenyl-4-(3,4,5- trimethoxybenzylidene) -1,3-oxazol-5(4H)-one

The crystal structure of (4Z)-2-phenyl-4-(3,4,5- trimethoxybenzylidene) -1,3-oxazol-5(4H)-one (PTMBO) was optimized by semi-empirical method, using MOPAC2012 program. The comparison of geometrically optimized molecule with the experimental structure described the role of different interactions on crystal packing. The calculation of parametric molecular electrostatic potential (PMEP) from semi-empirical method also supported the presence of crystal packing interactions and the antibacterial activity of the molecule. The small HOMO-LUMO energy gap of 7.379 eV obtained from molecular orbital calculations reflected the chemical activity of the molecule. Antibacterial action against E. coli and S. aureus was observed for title PTMBO compared to a reference Ampicillin drug. The ˜-electron delocalization in the chemical structure was studied through aromaticity of phenyl rings obtained from HOMED calculations