Abstract
Semicarbazone is a molecule with a group R1R2C=N-NR3-C(=O)-NR4R5.The oxygen atom has two free electron pairs; each nitrogen atom has one free electron pair. These free electron pairs are potential sites of coordination. The simplest molecule in this series is the semicarbazone which the formula is H2C=N-NH-C(=O)NH2. By replacing the oxygen atom by a sulfur atom is obtained a thiosemicarbazone. 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 semicarbazone and its methylated derivatives. 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 semicarbazones.Complexes of these ligands with the Zn (II) were modeled. The calculations were made by the method DFT / B3LYP with the orbital basis 6-31G (d, p).
Highlights
The study at the molecular level of the interaction between metals and bioligands is topical (Knouniats, 1990) (Williams, 1975) (Yatsimirskiï, 1976) (Kembal, 1975)
After studying the possibility of complexation of the different ligands with respect to criteria such as geometric parameters, atomic charges, HOMO components and the indexes of électrophilic superdelocalisability (IESD) of the atoms, we have modeled the formation of their respective complexes with zinc chloride (II)
This study allowed predicts the coordinatating sites of ligands by analysis of some system parameters known as coordinating indexes (CI)
Summary
The study at the molecular level of the interaction between metals and bioligands (proteins, nucleic acids, their fragments, and other substances contained in the organism) is topical (Knouniats, 1990) (Williams, 1975) (Yatsimirskiï, 1976) (Kembal, 1975). The bioinorganic chemistry which is currently in full swing is concerned, inter alias, with the coordination of trace elements with organic ligands. The results of these studies find their applications in various fields of science and technology such as medicine, agriculture, environmental protection, catalysis. Semicarbazones (SCZ) are molecules having a group R1R2C=N-NR3-C(=O)-NR4R5, having donor atoms (N and O) capable of forming bonds with complexing metals. They are of particular interest as ligands. Certain semicarbazones, such as nitrofurazone, and certain thiosemicarbazones are known for their antiviral, antibacterial, antitrypanosomal (antiparasitic), anticonvulsive, anti-tumor, anti-cancer, etc. activities, generally mediated by a binding with copper or iron (Picot, 2008) (Sakirigui et al, 2011) (Kenneth, 1999)
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