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  • Evidence for H-bonding interactions to the mu-eta2:eta2-peroxide of oxy-tyrosinase that activate its coupled binuclear copper site. Chemical communications (Cambridge, England) Kipouros, I., Stanczak, A., Culka, M., Andris, E., Machonkin, T. R., Rulisek, L., Solomon, E. I. 2022

    Abstract

    The factors that control the diverse reactivity of the mu-eta2:eta2-peroxo dicopper(II) oxy-intermediates in the coupled binuclear copper proteins remain elusive. Here, spectroscopic and computational methods reveal H-bonding interactions between active-site waters and the mu-eta2:eta2-peroxide of oxy-tyrosinase, and define their effects on the Cu(II)2O2 electronic structure and O2 activation.

    View details for DOI 10.1039/d2cc00750a

    View details for PubMedID 35237779

  • Impact of Intramolecular Hydrogen Bonding on the Reactivity of Cupric Superoxide Complexes with O-H and C-H Substrates. Angewandte Chemie (International ed. in English) Diaz, D. E., Quist, D. A., Herzog, A. E., Schaefer, A. W., Kipouros, I. n., Bhadra, M. n., Solomon, E. I., Karlin, K. D. 2019

    Abstract

    A series of TMPA-based copper(I) complexes (TMPA ≡ tris(2-pyridylmethyl)amine), with and without secondary coordination sphere hydrogen-bonding moieties, were prepared and reactivity with O2 at -135 °C in 2-methyltetrahydrofuran (MeTHF) was studied. H-bonding moieties are demonstrated to play a crucial role in the kinetic stabilization of [((X1)(X2)TMPA)CuII(O2•-)]+ cupric superoxide species, sustaining these primary copper-dioxygen compounds rather than subsequent secondary dicopper-dioxygen adducts. Support for the presence of H-bonding to the Cu-O-O•- superoxide O-atom(s) comes from resonance Raman (rR) spectroscopy, analogy to azido analogues [((X1)(X2)TMPA)CuII(N3-)]+, and the alternative O2 reactivity behavior of ligand-CuI complexes when an H-bonding modality is replaced by a methyl group. A dramatic enhancement in cupric superoxide reactivity towards phenolic substrates, as well as oxidation of substrates possessing moderate C-H BDEs is observed, correlating with the number and strength of the H-bonding groups.

    View details for DOI 10.1002/anie.201908471

    View details for PubMedID 31469942