Coordination compounds of copper have been invoked as major actors in processes involving the reduction of molecular oxygen, mostly with the generation of radical species the assignment for which has, so far, not been fully addressed. In the present work, we have carried out studies in solution and on surfaces to gain insights into the nature of the radical oxygen species (ROS) generated by a copper(II) coordination compound containing a thioether clip-phen derivative, 1,3-bis(1,10-phenanthrolin-2-yloxy)-N-(4-(methylthio)benzylidene)propan-2-amine (2CP-Bz-SMe), enabling its adsorption/immobilization to gold surfaces. Whereas surface plasmon resonance (SPR) and electrochemistry of the adsorbed complex indicated the formation of a dimeric Cu(I) intermediate containing molecular oxygen as a bridging ligand, scanning electrochemical microscopy (SECM) and nuclease assays pointed to the generation of a ROS species. Electron paramagnetic resonance (EPR) data reinforced such conclusions, indicating that radical production was dependent on the amount of oxygen and H2 O2 , thus pointing to a mechanism involving a Fenton-like reaction that results in the production of OH(.) .

The interplay between coordination geometry and reactivity in copper complexes has been widely studied for years. For CuII, it is known that the reduction is favored when the geometry is...

A new helical dimeric copper(I) complex [Cu(2)(mphenpr)(2)](ClO(4))(2) where mphenpr is 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane has been prepared and characterized by X-ray crystallography and NMR. In the solid state, the metal centers are 6.42 A apart, and the electronic structure has been investigated with use of density functional theory (DFT) calculations. In solution the dimer equilibrates with a monomeric form [Cu(mphenpr)](ClO(4)), and the mechanism of unfolding of the dimer into monomer has been studied. In the presence of CCl(4), formation of the monomer is coupled to the reductive dehalogenation of the halocarbon. The mechanism of this process has been probed by the study of short-lived potential reaction intermediates using fast kinetic pulse radiolysis techniques and comparisons with DFT calculations. The copper(II) product [Cu(mphenpr)Cl](ClO(4)) and an analogue [Cu(mphenpr)](ClO(4))(2) have been isolated and characterized by X-ray crystallography.

Complexation of copper(I) with the binucleating ligand, 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane, mphenpr, result in formation of helical dimers, [Cu2(mphenpr)2](2+). The resolution of the enantiomeric forms of the dimers has been carried out with Δ-[As(cat)3](-) as resolving agent and X-ray structures for two compounds, P-[Cu2(mphenpr)2](Δ-[As(cat)3])2 and P-[Cu2(mphenpr)2](Δ-[As(cat)3])2·4(CH3CN), are reported. The rate of racemization in poorly-coordinating solvents has been examined by (1)H NMR, and is slow. At saturating concentrations of [[Cu2(mphenpr)2](2+)] in acetonitrile, crystals of the helical trimeric complex [Cu3(mphenpr)3](ClO4)3 are obtained. The X-ray structure of the trimer is reported. This species has also been resolved. As with the helical dimer, racemization in poorly-coordinating solvents is slow, and circular dichroism and (1)H NMR spectra are reported. The absolute configuration of the resolved complex, P-[Cu3(mphenpr)3](Δ-[As(cat)3])3, has been determined by X-ray crystallography.