Mimicking mineral neogenesis for the clean synthesis of metal–organic materials from mineral feedstocks: coordination polymers, MOFs and metal oxide separation†
We present a systematic study of a mild approach for the activation of metal oxides, involving reactivity and self-assembly in the solid state, which enables their solvent-free chemical separation and direct solvent-free and low-energy conversion into coordination polymers and open metal–organic frameworks (MOFs). The approach is inspired by geological biomineralization processes known as mineral weathering, in which long-term exposure of oxide or sulfide minerals to molecules of biological origin leads to their conversion into simple coordination polymers. This proof-of-principle study shows how mineral neogenesis can be mimicked in the laboratory to provide coordination polymers directly from metal oxides without a significant input of either thermal or mechanical energy, or solvents. We show that such “aging” is accelerated by increased humidity, a mild temperature increase and/or brief mechanical activation, enabling the transformation of a variety of high-melting (800 °C–2800 °C) transition (MnII, CoII, NiII, CuII, and Zn) and main group (Mg and PbII) oxides at or near room temperature. Accelerated aging reactions are readily scaled to at least 10 grams and can be templated for the synthesis of two-dimensional and three-dimensional anionic frameworks of Zn, Ni(II) and Co(II). Finally, we demonstrate how this biomineralization-inspired approach provides an unprecedented opportunity for solvent-free chemical segregation of base metals, such as Cu, Zn and Pb, in their oxide form under mild conditions.