Reaction of the bridging ligand 3,6-bis-[6'-(1' ',8' '-naphthyrid-2' '-yl)-pyrid-2'-yl]pyridazine (1) with [Ru(DMSO)4Cl2] in aqueous ethanol followed by excess 4-substituted pyridine (4-R-py) in the presence of triethylamine provides a series of three well-organized dinuclear complexes characterized by 1H NMR, MS, and X-ray. Mononuclear analogues are prepared from 4-tert-butyl-2,6-di(1',8'-naphthyrid-2'-yl)pyridine (5) and characterized in a similar fashion. All six complexes show electronic absorption and redox properties consistent with the electron donor/acceptor ability of the axial 4-R-py ligand. When an acetonitrile solution of the catalyst is added to an aqueous Ce(IV)-CF3SO3H solution (pH = 1.0) at 24 degrees C, oxygen evolution is observed for both mono and dinuclear systems. Turnover numbers range from 50 to 3200 with the best results being found when the axial ligand is 4-methylpyridine (mononuclear TN = 580 and dinuclear TN = 3200).
NIR‐Absorbing Ru
<sup>II</sup>
Complexes Containing α‐Oligothiophenes for Applications in Photodynamic Therapy
作者:Liubov M. Lifshits、John A. Roque、Houston D. Cole、Randolph P. Thummel、Colin G. Cameron、Sherri A. McFarland
DOI:10.1002/cbic.202000419
日期:2020.12.11
report the first NIR‐RuII photosensitizers found to be phototoxic to cancer cells, including highly pigmented melanoma cells. They incorporate a bis(1,8‐naphthyridine)‐based ligand, a bidentate thiophene‐based ligand, and a monodentate 4‐picoline ligand. Transient absorption measurements indicate that four thiophenes are required to access the 3ILCT state for eliciting photodynamictherapy effects.
A Ru(II) Bis-terpyridine-like Complex that Catalyzes Water Oxidation: The Influence of Steric Strain
作者:Nattawut Kaveevivitchai、Lars Kohler、Ruifa Zong、Maya El Ojaimi、Nirja Mehta、Randolph P. Thummel
DOI:10.1021/ic4016383
日期:2013.9.16
The complexation of 2,9-dicarboxy-1,10-phenanthroline (DPA) with [Ru(tpy)Cl-3] (tpy = 2,2';6,2 ''-terpyridine) provides a six-coordinate species in which one carboxyl group of DPA is not bound to the Ru(II) center. A more soluble tri-t-butyl tpy analogue is also prepared. Upon oxidation, neither species shows evidence for intramolecular trapping of a seven-coordinate intermediate. The role of the tpy ligand is revealed by the preparation of [Ru(tpy)(phenq)](2+) (phenq = 2-(quinol-8'-yl)-1,10-phenanthroline) that behaves as an active water oxidation catalyst (TON = 334). This activity is explained by the expanded coordination geometry of the phenq ligand that can form a six-membered chelate ring that better accommodates the linear arrangement of axial ligands required for optimal pentagonal bipyramid geometry. When a 1,8-naphthyidine ring is substituted for each of the two peripheral pyridine rings on tpy, increased crowding in the vicinity of the metal center impedes acquisition of the prerequisite reaction geometry.