Synthesis and DNA interaction of a Sm(III) complex of a Schiff base derived from vanillin and L-tryptophan
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 oC 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.
KEY WORDS: Vanillin, L-Tryptophan, Sm(III) complex of Schiff base, Herring sperm DNA, Interaction
Bull. Chem. Soc. Ethiop. 2011, 25(2), 197-207.