New cyclometallated Ru(II) complex for potential application in photochemotherapy?
In an effort to create a molecule that absorbs further into the optimum window for photochemotherapy (PCT), the new cyclometallated complex [Ru(biq)2(phpy)](PF6) (1, biq = 2,2'-biquinoline, phpy(-) = deprotonated 2-phenylpyridine) was synthesized, characterized and compared to the known photoactive complexes [Ru(biq)2(bpy)](PF6)2 (2, bpy = 2,2'-bipyridine) and [Ru(biq)2(phen)](PF6)2 (3, phen = 1,10-phenanthroline), both of which undergo exchange of one biq ligand when irradiated with red light in coordinating solvents. Excited state ligand dissociation in 2 and 3 is believed to be related to the steric hindrance afforded by the presence of two coordinated biq ligands. The ligand exchange quantum yield of 2 is ~2-fold greater than that of 3, which was shown to be cytotoxic when irradiated with visible light. Cyclometallation results in a red shift of the MLCT absorption maximum of ` by ~100 nm relative to those of 2 and 3, but, although 1 exhibits a distorted octahedral geometry, photoinduced ligand exchange does not occur. DFT calculations were used to aid in our understanding of the lack of photochemistry of 1 which is explained by the destabilization of the eg(σ*) orbitals upon cyclometallation.
Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA. turro.1@osu.edu.
Bryan A
BA
Albani
Bruno
B
Peña
Kim R
KR
Dunbar
Claudia
C
Turro
D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry* / Q000627:therapeutic use; D055668:Photochemical Processes; D010778:Photochemotherapy; D011725:Pyridines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
D009942:Organometallic Compounds; D011725:Pyridines; C058324:2-phenylpyridine; D012428:Ruthenium