Supramolecular control of monooxygenase reactivity in a copper(ii) cryptate.
We report a detailed investigation of the formation and self-decomposition of Cu(ii)-hydroperoxo intermediates under the influence of second-coordination-sphere features provided by a cryptand. In solution, an equilibrium between two copper complexes with square-planar and square-pyramidal geometries was identified. Upon addition of H2O2/Et3N, two copper(ii)-hydroperoxo intermediates formed at different rates. Their decomposition via self-oxidation was probed by deuterating select positions on the cryptand. This led to a small kinetic isotope effect of 1.5. Mass spectrometry analysis of the demetallated organic products is consistent with a direct oxygen-atom transfer to a tertiary amine on the cryptand, forming an N-oxide, unlike other models of copper mononuclear monooxygenase enzymes.
Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West, Montreal, H4B 1R6, Canada. dr.x@concordia.ca.
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Chaloner
Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West, Montreal, H4B 1R6, Canada. dr.x@concordia.ca.
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Khomutovskaya
Équipe de Chimie Inorganique Redox, Département de Chimie Moléculaire, Université Joseph Fourier, 38041 Grenoble, Cedex 9, France.
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Thomas
Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West, Montreal, H4B 1R6, Canada. dr.x@concordia.ca.
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Ottenwaelder
D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D013058:Mass Spectrometry; D006899:Mixed Function Oxygenases / Q000737:chemistry*; D008958:Models, Molecular
D003300:Copper; D006899:Mixed Function Oxygenases