<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 nSm(III) : nK[HL] = 1:1 and nSm(III)L : nDNA = 5:1 were confirmed by a mole ratio method. The calculated binding constants of [Sm(III)L]+ with DNA at 25 and 37 C were 1.19 × 105 M-1 and 3.96 × 104 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.

Keywords

• Vanillin
• L-Tryptophan
• Sm(III) complex of Schiff base
• Herring sperm DNA
• Interaction