The present paper describes the syntheses, characterization of some new coordination compounds of organotin(IV) with Schiffbases derived by condensation of heterocyclic ketones and amino acids, viz. glycine, β-alanine, α-valine, α-isoleucine and α-tryptophan. The newely prepared compounds have been characterized by elemental analysis, conductance measurements, molecular weight determinations, infrared and nuclear magnatic resonance (1H, 13C and 119Sn NMR) spectral studies. An trigonal bipyramidal geometry has been proposed for all of the complexes. A few representative ligands and their tin complexes have also been screened for their antibacterial activities and found to be quite active in this respect.

Studies on Coordination Compounds of Organotin(IV) with Schiff Bases of Amino Acids

Structure and characterization of N-(2-hydroxy-1-naphthylidene)threonine

A new copper(II) complex, [Cu(naph-leu)phen]CH3OH·0.5H2O, in which naph-leu is the tridentate Schiff base ligand derived from the condensation of 2-hydroxy-1-naphthaldehyde and L-leucine, phen is phenanthroline, has been synthesized and characterized by elemental analyses, IR spectra and single crystal X-ray diffraction. The DNA-binding properties of this complex have been investigated by absorption spectra, fluorescence spectra and circular dichroism (CD) spectra, as well as viscosity measurement. Results show that this copper(II) complex binds to calf thymus DNA (CT-DNA) in an intercalative mode and its intrinsic binding constant Kb is 4.87×103 L·mol−1. Furthermore, the DNA cleavage activity of this copper(II) complex has also been investigated by submarine gel electrophoresis. Interestingly, it was found that this complex can cleave the supercoiled plasmid pBR322 DNA to both nicked and linear forms.

Synthesis, Characterization, DNA-binding Properties and DNA Cleavage of a New Ternary Copper(II) Complex with Mixed-ligands of Tridentate Schiff Base and 1,10-Phenanthroline

New Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) chelates of the Schiff base derived from isatin witho-phenylenediamine have been synthesized and characterized on the basis of elemental analyses, electronic, IR and1H NMR spectra, and also by aid of molar conductivity and magnetic moment measurements. It has been found that the Schiff base behaves as ONNO tetradentate dibasic ligand forming chelates with 1:1 (metal:ligand) stoichiometry. Square planar environment is suggested for nickel(II) chelate. All the metal chelates show non-electrolytic behaviour.

Metal chelates of some transition and non-transition metal ions with Schiff base derived from isatin with o -phenylenediamine

The electronic absorption spectra of five Schiff bases derived from 2-hydroxy-1-naphthaldehyde with glycine, alanine, leucine, valine and phenylalanine have been measured in various solvents. The observed bands were assigned to the proper electronic transitions and compared with the predicted transitions at the semiempirical level of theory. The calculated equilibrium constants are in agreement with the experimental results, predicting the existence of all studied compounds predominantly or completely in keto-imine tautomerism. On the other hand, a correlation between ν (cm ‒1 ) (main frequency of each compound) and the well known solvent parameters ET (30), er, π* has been made. Furthermore, the acid dissociation constants, pKa, were determined by using three different spectrophotometric methods.

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A.A. Moustafa

Papers

Ni(II) complexes of some polyfunctional n-Naphthylideneamino acids