Quantum-chemical study of the coordination of some aromatic derivatives of semicarbazone

Abstract

Semicarbazone is a molecule having the R1R2C=N-NR3-C(=O)-NR4R5 general formula. The oxygen atom with its two free electron pairs in on hand, and each nitrogen atom with its one free electron pair in the other hand are potential coordination sites. The simplest molecule in this series is the semicarbazone which formula is H2C=N-NH-C(=O)NH2. Some semicarbazones, such as nitrofurazone, and some thiosemicarbazones are known to have many properties: antiviral, antibacterial, antitrypanosomal, anticonvulsant, antitumor, anticancer. They are usually mediated by an association with copper or iron. Indeed transition metal complexes with given chemical structures are useful alternatives in the treatment of certain diseases since coordination of active ingredients deeply modifies both the physiological properties of metals and ligands in the meaning of overall improvement of these properties. The present work focuses on quantum study of the complexation of some aromatic derivatives of semicarbazone. The purpose of this study is to determine the most favorable coordination site of each of these ligands. It was found that the oxygen atom appears more favorable to the coordination of the aromatic derivatives of semicarbazone. Complexes of these ligands with the Zn (II) were modeled. The calculations were made the DFT/B3LYP level with the 6-31G (d, p) orbital basis set