A structurally flexible triazolate-based metal–organic framework featuring coordinatively unsaturated copper(i) sites

Abstract

The novel metal–organic framework CFA-8 (Coordination Framework Augsburg University-8), [Cu₂(tqpt)], containing the organic linker H₂-tqpt {H₂-tqpt = 6,6,14,14-tetramethyl-6,14-dihydroquinoxalino[2,3-b]phenazinebis-triazole}, has been synthesized. Reaction of H₂-tqpt and anhydrous CuCl₂ in N,N-dimethylacetamide (DMA) yields CFA-8 as orange crystals with lenticular shape. This framework shows a reversible breathing effect and is robust upon solvent removal. It has been characterized by single-crystal and powder X-ray diffraction, TGA, IR spectroscopy and gas sorption measurements. CO adsorption isotherms show that Cu(I) sites in this framework are able to bind carbon monoxide forming a weak complex which has been additionally characterized by IR spectroscopy and synchrotron powder X-ray diffraction measurements.