Relationships between structure, retention and biological activity of some Schiff base ligands and their complexes

The lipophilicity of a series of Schiff base ligands and their complexes with nickel(II) and copper(II) has been determined by reversed-phase thin-layer chromatography using binary dioxane-water mobile phase. Chelate ligands were prepared by condensation of diamine and the corresponding beta-diketone. Copper(II) and nickel(II) complexes with chelate ligands containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione, pentane-2,4-dione and/or 1,1,1-trifluoropentane-2,4-dione, or 1,1,1-trifluoropentane-2,4-dione and/or 1-phenylbutane-1,3-dione as the beta-diketone part were synthesized. Some of investigated compounds were screened for their in vitro antifungal activity against Sacharomyces cerevisiae and antibacterial activity against Escherichia coli. Chromatographically obtained lipophilicity parameters were correlated both with calculated n-octanol-water partition coefficient C log P and antimicrobial activities. Satisfactory correlations were obtained. Chromatographic data proved to be reliable parameters for describing the lipophilic properties of the investigated compounds. Additionally, the principal components analysis was performed on the data chromatographically obtained. This statistical method was useful for distinguishing compounds and objective comparison of their lipophilicity parameters.