Yves Les Mest のCu TPA 錯体のレドックスに伴うH2Oの配位、脱配位に関する論文。
電気化学。
DOI: 10.1039/C3DT53548G
Received 18 Dec 2013, Accepted 07 Feb 2014
First published online 10 Feb 2014
電気化学。
Paper
Insights into water binding/unbinding associated to the CuII/CuI electron transfer at a biomimetic Cu centre
Dalton Trans., 2014, Accepted Manuscript
DOI: 10.1039/C3DT53548G
Received 18 Dec 2013, Accepted 07 Feb 2014
First published online 10 Feb 2014
The coordination properties of the biomimetic complex [Cu(TMPA)(H2O)](CF3SO3)2 (TMPA=tris(2-pyridylmethyl)amine) have been investigated by electrochemistry combined to UV-Vis and EPR spectroscopies in different non-coordinating media including imidazolium-based room-temperature ionic liquids, for different water contents. The solid-state X-ray diffraction analysis of the complex shows that the cupric centre lies in a N4O coordination environment with a nearly perfect trigonal bipyramidal geometry (TBP), the water ligand being axially coordinated to CuII. In solution, the coordination geometry of the complex remains TBP in all media. Neither the triflate ion nor the anions of the ionic liquids were found to coordinate the copper centre. Cyclic voltammetry in all media shows that the decoordination of the water molecule occurs upon monoelectronic reduction of the CuII complex. Back-coordination of the water ligand at the cuprous state can be detected by increasing the water content and/or decreasing the timescale of the experiment. Numerical simulations of the voltammograms allow the determination of kinetics and thermodynamics for the water association-dissociation mechanism. The resulting data suggest that (i) the binding/unbinding of water at the CuI redox state is relatively slow and equilibrated in all media, and (ii) the binding of water at CuI is somewhat faster in the ionic liquids than in the non-coordinating solvents, while the decoordination process is weakly sensitive to the nature of the solvents. These results suggest that ionic liquids favour water exchange without interfering with the coordination sphere of the metal centre. This makes them promising media for studying host-guest reactions with biomimetic complexes.
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