DefinePK

Abstract

Theoretical studies on six thiourea derivatives - C6H5(CO)-N-CS-N-C6H4X (where X = H, Cl, Br, NO2, CH3 or OCH3 located at the para position) have been made for a single molecule. By employing the Density Functional Theory at the B3LYP level for a single molecule, it shows that all the compounds have a rotational barrier at the thiourea moiety caused by the intra-molecular hydrogen bond that forms a pseudo-six-membered ring C2-N3-C5-O6---H-N4. Optimized parameters agree well with the experimental data. The general trend observed for the parameters of the optimized geometry for all compounds is influenced by the electronic properties of the substituent on the phenyl ring. The highest occupied molecular orbital (HOMO) and Lowest unoccupied molecular orbital (LUMO) characteristics, hardness and electro negativity are closely related to the electronic properties of the substituent group. Harmonic oscillator model of electron delocalization (HOMED) analysis provides that aromaticity is influenced by electronic properties of substituent group.