Syntheses, characterization and DNA-binding studies of ruthenium(II) terpyridine complexes:: [Ru(tpy)(PHBI)]2+ and [Ru(tpy)(PHNI)]2+

Two novel tridentate ligands, 2-(2-benzimidazole)-1,10-phenanthroline (PHBI) and 2-(2-naphthoimidazole)-1,10-phenanthroline (PHNI), and their heteroleptic complexes [Ru(tpy)(PHBI)](ClO4)(2).2H(2)O (1) and [Ru(tpy)(PHNI)](CIO4)(2).H2O (2) (tpy=2,2':6',2-terpyridyl) have been synthesized and characterized by elemental analysis, mass spectra, H-1 NMR, and electronic spectroscopy. The electrochemical behaviors of the two novel complexes were studied by cyclic voltammetry. The DNA-binding properties of the two complexes were investigated by spectroscopic methods and viscosity measurements. The results indicated that the two complexes interact with DNA in different binding modes. Complex 1 may bind to DNA via electrostatic interaction, while complex 2 binds to DNA by partial intercalation via the extended naphthyl ring into the base pairs of DNA. (C) 2002 Elsevier Science Inc. All rights reserved.