Two new water-soluble Cr(III) complexes [Cr(IP)(2)Cl(2)](+) and [Cr(PIP)(2)Cl(2)](+) (IP = imidazo[4,5-f][1,10]phenanthroline, PIP = 2-phenylimidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized by elemental analysis, mass spectra, and ultraviolet-visible spectra. The DNA-binding properties of the two complexes were investigated by spectroscopic methods and viscosity measurements. The results indicate that both complexes bind to DNA via an intercalative mode with moderate strength. The fluorescence intensity of both complexes decreases with increasing DNA concentration, similar to those of [Cr(phen)(3)](3+) and [Cr(bpy)(3)](3+). Also, both complexes can cleave pBR-322 DNA in the presence of H(2)O(2), and [Cr(PIP)(2)Cl(2)](+) exhibits more effective activity than [Cr(IP)(2)Cl(2)](+) under the same condition.

A heterodinuclear (Ru(II), Co(III)) metal polypyridyl complex [(phen)(2)Ru(bpibH(2))Co(phen)(2)](5+) {phen = 1,10-phenanthroline, bpibH(2) = 1,4-bis([1,10]phebanthroline-[5,6-d]imidazol-2-yl)-benzene} has been designed and synthesized. The comparative study on the interactions of the Ru(II)-Co(III) complex with calf thymus DNA (CT-DNA) and yeast tRNA has been investigated by UV-visible spectroscopy, fluorescence spectroscopy, viscosity, as well as equilibrium dialysis and circular dichroism (CD). The antitumor activities of the complex have been evaluated by MTT {3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide} method and Giemsa staining experiment. These results indicate that the structures of nucleic acids have significant effects on the binding behaviors of metal complexes. Furthermore, the complex demonstrates different antitumor activity against selected tumor cell lines in vitro, and can make the cell apoptosis.

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A new ligand {2-(5-nitro-furan-2-yl)-1H-1,3,7,8-tetraaza-cyclopenta[l]-phenanthrene} (nftp) and its Ru(II) complexes [Ru(phen)(2)(nftp)](2+) (1) (phen = 1,10-phenanthroline) and [Ru(bpy)(2)(nftp)](2+) (2) (bpy = 2,2'-bipyridine) were synthesized and characterized. The binding properties of the two complexes to calf thymus-DNA (CT-DNA) were investigated by different spectrophotometric methods and viscosity measurements together with equilibrium dialysis and circular dichroism spectroscopy. The results suggest that both complexes bind to DNA through intercalation and enantioselectively interact with CT-DNA. However, complex 1 is a better candidate as an enantioselective binder to CT-DNA than complex 2. Although no emission is generally observed in water or organic solvents for Ru(II) polypyridyl complexes with a nitro group, complexes 1 and 2 can emit luminescence in both media. When irradiated at 365 nm, complex 1 cleaves DNA more effectively than complex 2.

A novel polypyridyl ligand phenyl- (4,5,9,14-tetraaza-benzo[b]triphenylen-1,1-yl)-methanone (PTBM) and its complexes [Ru(phen) 2 (PTBM)] 2+ (1) (phen = 1,10-phenanthroline) and [Ru(bpy) 2 (PTBM)] 2+ (2) (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, mass spectroscopy, and 1 H NMR. The DNA-binding properties of the two complexes were investigated by spectroscopic and viscosity measurements. The results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 1 is greater than that of complex 2. When irradiated at 365 nm, complex 1 was found to be a more-effective DNA-cleaving agent than complex 2.