title: Photoinduced intercalation and coordination of a dirhodium complex to DNA: dual DNA binding.
abstract: Two new complexes, cis-H,H-[Rh2 (OCCH3 NH)2 (LL)(CH3 CN)2 ](2+) , where LL=bpy (2, bpy=2,2'-bipyridine) and dppz (3, dppz=dipyrido[3,2-a:2',3'-c]phenazine), were prepared from the reaction of cis-H,H-[Rh2 (OCCH3 NH)2 (CH3 CN)6 ](2+) (1) with the corresponding bidentate ligand. The bpy and dppz ligands chelate to the same rhodium atom and are positioned trans to the amidato N atoms, as determined by the single crystal X-ray structure of 2. Irradiation of 2 and 3 with visible light in water results in the exchange of one CH3 CNeq ligand for an H2 O molecule with quantum yields, Φ400 , of 0.040 and 0.044, respectively (λirr =400 nm). The identities of the photoproducts of 2 and 3 were determined to be cis-H,H-[Rh2 (OCCH3 NH)2 (L)(H2 O)(CH3 CN)](2+) , where L is bpy (4) and dppz (5), respectively. Mobility shift assays show that 4 crosslinks double-stranded DNA, and ESI-MS experiments indicate that both 4 and 5 form covalent adducts with single-stranded DNA. In addition, relative viscosity and 2D NMR experiments show that the dppz ligand of 5 also intercalates into DNA upon irradiation, making 3 a dual-binding agent that both intercalates and covalently binds to DNA upon the absorption of visible light.
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Ave Columbus, OH 43210 (USA).
authors.forename: Alycia M
authors.initials: AM
authors.lastname: Palmer
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Burya
authors.forename: Judith C
authors.initials: JC
authors.lastname: Gallucci
authors.forename: Claudia
authors.initials: C
authors.lastname: Turro
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D007364:Intercalating Agents / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011789:Quantum Theory; D012238:Rhodium / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014783:Viscosity
chemical_list: D056831:Coordination Complexes; D004277:DNA, Single-Stranded; D007364:Intercalating Agents; D015082:2,2'-Dipyridyl; D012238:Rhodium
keywords: dirhodium; dual binding; intercalation; photo-active compounds; photodynamic therapy