Interaction of chromium(III) complex of chiral binaphthyl tetradentate ligand with DNA Original Research Article

Since conformation of the molecule plays a vital role in the activity of drug, we have investigated the DNA interaction of a chromium(III) complex with ligands in two conformations. Chromium(III) complexes derived from chiral binaphthyl Schiff base ligands, viz. R- and S-2,2′-bis(salicylideneamino) 1,1′-binaphthyl, have been synthesized and characterized by mass, IR, and electronic spectra. The interaction of these R- and S-binaphthyl Schiff base chromium(III) complexes with CT–DNA was investigated with the goal of examining whether the chirality has an influence on the chromium(III)–DNA binding properties. The difference in chirality of the ligand did not show any striking difference in binding properties. The binding constants for R and S conformers were estimated to be 18 (±0.4) × 103 and 9.4 (±0.3) × 103 M−1, respectively, through spectroscopic titrations. All the experimental results are suggestive that both the isomers are DNA groove binders. The results of steady-state as well as time-resolved fluorescence experiments, however, suggest that the R conformer has restricted mobility when bound to DNA because it is more deeply buried in the groove of DNA compared to the S isomer.