<b>Synthesis and DNA interaction of a Sm(III) complex of a Schiff base derived from vanillin and L-tryptophan</b>

Abstract

The interaction between the Sm(III) complex of an ionic Schiff base [HL] - , derived from vanillin and L-tryptophan, and herring sperm DNA at physiological pH (7.40) has been studied by UV-Vis absorption, fluorescence and viscosity methods. The binding ratios n Sm(III) : n K[HL] = 1:1 and n Sm(III)L : n DNA = 5:1 were confirmed by a mole ratio method. The calculated binding constants of [Sm(III)L] + with DNA at 25 and 37 o C were 1.19 × 10 5 M -1 and 3.96 × 10 4 M -1 , respectively. The thermodynamic parameters demonstrate that the interaction between [Sm(III)L] + and DNA is driven mainly by enthalpy. Fluorimetric studies show that [Sm(III)L] + is able to displace intercalated acridine orange. Combined with Scatchard methods, circular dichroism spectroscopy and viscosity measurements, the results indicate that the interaction between [Sm(III)L] + and herring sperm DNA is mainly by intercalation with some groove binding. KEY WORDS : Vanillin, L-Tryptophan, Sm(III) complex of Schiff base, Herring sperm DNA, Interaction Bull. Chem. Soc. Ethiop. 2011 , 25(2), 197-207.