Trinuclear zinc complexes for biologically relevant μ3-oxoanion binding and carbon dioxide fixation.

Abstract

Tremendous efforts have been made to model multinuclear zinc enzymes. Despite such efforts, it remains a challenge to design single molecules that stabilize μ3-oxoanion-bridged trinuclear zinc cores as analogues of enzymatic active sites. The conversion of carbon dioxide to carbonates is a biological process mediated by carbonic anhydrases and a natural process for large-scale carbon dioxide fixation. Here we report a trinuclear zinc scaffold for capturing biologically relevant μ3-oxoanions, such as phosphate and carbonate, and its ability to catalytically convert carbon dioxide to carbonates. Structurally characterized {Zn3(μ3-PO4)} and {Zn3(μ3-CO3)} cores are observed in solution by nuclear magnetic resonance and high-resolution mass spectrometry. The activity of the μ3-carbonate unit can be sterically controlled, which makes the carbon dioxide fixation cycle feasible. Our results suggest that this trinuclear zinc scaffold catalytically converts carbon dioxide to carbonates under mild conditions and provides a good model for studying oxoanion-bridged zinc cores in solution.