Photoinduced interactions of two dirhodium complexes with d(GTCGAC)2 probed by 2D NOESY.

The interactions between the 6-mer duplex oligonucleotide d(GTCGAC)2 and the photoactive dirhodium complexes cis-H,H-[Rh2(HNOCCH3)2(L)(CH3CN)4](2+), where L represents bpy (1, 2,2'-bipyridine) and dppz (2, dipyrido[3,2-a:2',3'-c]phenazine), were probed using 2D (1)H-(1)H NOESY NMR spectroscopy. Complex does not interact with the duplex in the dark, but binds covalently to the terminal guanine following irradiation with visible light. Similar behavior was observed for 2, but in addition to the photoinduced covalent DNA binding, the planar dppz ligand of the complex shields the terminal cytosine protons after irradiation.

Tumoricidal activity of low-energy 160-KV versus 6-MV X-rays against platinum-sensitized F98 glioma cells.

The purposes of this study were (i) to investigate the differences in effects between 160-kV low-energy and 6-MV high-energy X-rays, both by computational analysis and in vitro studies; (ii) to determine the effects of each on platinum-sensitized F98 rat glioma and murine B16 melanoma cells; and (iii) to describe the in vitro cytotoxicity and in vivo toxicity of a Pt(II) terpyridine platinum (Typ-Pt) complex. Simulations were performed using the Monte Carlo code Geant4 to determine enhancement in absorption of low- versus high-energy X-rays by Pt and to determine dose enhancement factors (DEFs) for a Pt-sensitized tumor phantom. In vitro studies were carried out using Typ-Pt and again with carboplatin due to the unexpected in vivo toxicity of Typ-Pt.

Photoinduced intercalation and coordination of a dirhodium complex to DNA: dual DNA binding.

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.

Cytotoxicity of cyclometallated ruthenium complexes: the role of ligand exchange on the activity.

The cyclometallated Ru(II) complexes cis-[Ru(phpy)(phen)(CH3CN)2](PF6) (1; phpy(-)=deprotonated 2-phenylpyridine, phen=1,10-phenanthroline) and cis-[Ru(phpy)(bpy)(CH3CN)2](PF6) (2; bpy=2,2'-bipyridine) were investigated as potential agents for photodynamic therapy. The presence of phpy(-) in the coordination sphere results in a red-shift of the Ru→phen and Ru→bpy metal-to-ligand charge transfer of 1 and 2, respectively, thus improving the tissue penetration of light while maintaining the efficient photo-induced ligand exchange required for DNA binding. The 14-fold enhancement of OVCAR-5 cell death that occurs upon irradiation with 690 nm light can be attributed to photo-aquation.

Photoinduced ligand exchange and covalent DNA binding by two new dirhodium bis-amidato complexes.

Two new dirhodium complexes, the head-to-tail (H,T) and head-to-head (H,H) isomers of cis-[Rh(2)(HNOCCH(3))(2)(CH(3)CN)(6)](2+), were synthesized, separated, and characterized following the reaction of Rh(2)(HNOCCH(3))(4) with trimethyloxonium tetrafluoroborate in CH(3)CN. The products were characterized by (1)H NMR spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction. Each bis-amidato isomer has a total of six CH(3)CN ligands, two along the internuclear Rh-Rh axis, CH(3)CN(ax), two in equatorial positions trans to the oxygen atoms of the bridging amidato groups, CH(3)CN(eq)(O), and two in equatorial positions trans to the amidato nitrogen atoms, CH(3)CN(eq)(N).