Abstract

COMPUTATIONAL STUDY ON THE ELECTRONIC STRUCTURE OF PHENETHICILLIN-LACTIM-ENOL ZWITTERIONS BY AUSTIN MODEL-1 (AM1) METHOD

Pingili Kavitha Reddy and Bojja Rajeshwar Rao*

ABSTRACT

The geometry and electronic structure of phenethicillin-lactim-enol (1) tautomer and its zwitterions 2(N13H+) & 3(N7H+) have been optimized and calculated by using semi-empirical molecular orbital method (AM1), which includes experimental parameters and extensive simplification of the Schrodinger’s equation (HΨ=EΨ) for calculation of various properties in the gas phase. The mechanism of formation of zwitterions (2 & 3) has been investigated and observed that calculated heats of formation (ΔHfo in kcal) and dipole moment (μ in debye) are decreased in the order of 2>3>1. It is also investigated the net charges on N7 and N13 are increased in the order of 3<2<1 and 2<1<3 respectively. The effects of conformational changes and electronic properties have also been discussed for stable conformations.

Keywords: Phenethicillin-lactim-enol, zwitterions, HOMO, LUMO, frontier molecular orbitals.