Cu(i)Cu(ii)BTC, a microporous mixed-valence MOF via reduction of HKUST-1

Abstract

Metal–organic frameworks (MOFs) are typically crystalline microporous materials with metal ions of usually one oxidation state (although mixed-valence MOFs have been reported) and one type of co-ordination structure. Here, a microporous mixed-valence Cu(I,II)-MOF featuring a unique network of distinct Cu(I) and Cu(II) coordination sites is prepared by solvothermal reduction of HKUST-1. Like HKUST-1, this compound is assembled solely from Cu ions and benzene 1,3,5-tricarboxylate (BTC) ligands. The new MOF exhibits dual micropore size distribution and shows superior water stability compared to HKUST-1.