Metal chelates of ampicillin versus amoxicillin: synthesis, structural investigation, and biological studies

Solid chelates derived from some alkaline earth and transition metal complexes with ampicillin (Hamp, a) and amoxicillin (Hamox, b) were synthesized and characterized using elemental analysis, molar conductivity, IR, magnetic susceptibility, and thermogravimetric studies. Both drugs behave as tetradentate ligands coordinating to metal through amino, imino, and carboxylate as well as through -lactamic carbonyl. All chelates have octahedral geometry except Cu(II) complexes which have square planar structure and uranium has pentagonal bipyramidal coordination. 1H- and 13C-NMR of the Zn(II) and UO2(VI) chelates are compared with the free ligands. The antimicrobial activity of the prepared chelates was determined.