Available online www.jocpr.com Journal of Chemical and Pharmaceutical Research, 2012, 4(1):27-32 Research Article ISSN : 0975-7384 CODEN(USA) : JCPRC5 27 Some Theoretical Study on the Interaction Between of a Salen Schiff-base Ligand with Zn (II), Cd (II) and Hg (II) Ions Mahdeyeh Sheikhshoaie 1,3 , Tayebeh Shamspur 2 , S. Zia Mohammadi 3 1,2 Shahid Bahonar University of Kerman, Iran 3 Chemistry Department, Payame-Noor University (PNU), Kerman, Iran _____________________________________________________________________________________________ ABSTRACT A theoretical study based on the optimum angle and distance between salen Schiff base and Zn (II), Cd (II) and Hg (II) ions was conducted. These investigations were carried out based on ab-initio calculations, to estimate the pair wise interaction energy between the two molecules. In this study the geometries of metal complexes of Zn (II), Cd (II) and Hg (II) ions with salen Schiff base were studied. Key words: Schiff base, Theoretical study, Schiff base, Interaction, Salen, DFT. _____________________________________________________________________________________________ INTRODUCTION The Schiff bases derived from salicylaldehyde (salen) as polydentate ligands are known to form very stable complexes with transition metal ions [1]. The resulting salen complexes have attracted increasing attention, mainly due to their peculiar properties [2-6] and their reactivity mainly in the area of binding small molecules. Schiff bases reagents are becoming increasingly important in the pharmaceutical, dye, and plastic industries as well as for liquid- crystal technology and mechanistic investigations of the drugs used in pharmacology, biochemistry, and physiology [7]. However, despite extensive scientific reports on the synthesis, characterization, and crystalline structure of the transition metal–salen complexes, there have been only limited reports on the use of salen molecules as ionophores in ion-selective studies [8-14]. Quantum chemical calculations have been shown to be useful in the description of the relationship among the electronic structures of the molecular systems. Salen Schiff base has four coordination sites, two nitrogen atoms from the imino groups and two oxygen atoms in hydroxyl groups [Scheme 1]. N N HO OH 1 2 3 4 Scheme 1. The structure of Salen Schiff base compound (H 2 L)