AM1 study on the conformations of zwitterions of 6-aminopenicillanic acid (6-APA)

摘要

The geometry and electronic structure of zwitterions of 6-aminopcnicillanic acid (6-APA) have been optimized and calculated by semi-empirical molecular orbital AM1 method.The mechanism of formation of zwitterions of 6-APA has been studied by comparison of the different positions of net charges on nitrogen atoms in the molecule.In this connection,the heats of formation (△H_f°),dipole moments (μ),ionization potentials (IP),full atomic charges,and energies of frontier molecular orbital (E_HOMO and E_LUMO) have been performed and discussed.The effect of conformational changes and electronic properties of stable conformations have been determined.