Heterogeneous catalase-like activity of gold(i)–cobalt(iii) metallosupramolecular ionic crystals

Abstract

Unique heterogeneous catalase-like activity was observed for metallosupramolecular ionic crystals [Au^I₄Co^III₂(dppe)₂(D-pen)₄]X_n ([1]X_n; dppe = 1,2-bis(diphenylphosphino)ethane; D-pen = D-penicillaminate; X_n = (Cl⁻)₂, (ClO₄⁻)₂, (NO₃⁻)₂ or SO₄²⁻) consisting of Au^I₄Co^III₂ complex cations, [1]²⁺, and inorganic anions, X⁻ or X²⁻. Treatment of the ionic crystals with an aqueous H₂O₂ solution led to considerable O₂ evolution with a high turnover frequency of 1.4 × 10⁵ h⁻¹ for the heterogeneous cobalt complexes, which was dependent on their size and shape as well as the arrangement of cationic and anionic species. These dependencies were rationalized by the presence of cobalt(II) centers on the crystal surface and their efficient exposure on the (111) plane rather than the (100) plane based on morphological and theoretical studies.