Postsynthetic Paddle-Wheel Cross-Linking and Functionalization of 1,3-Phenylenebis(azanetriyl)tetrabenzoate-Based MOFs

Abstract

A new metal–organic framework, Cu2(mpbatb)(H2O)2 (DUT-71; DUT, Dresden University of Technology) (mpbatb, 4,4′,4″,4‴-(1,3-phenylenebis(azanetriyl)tetrabenzoate)), was prepared by a solvothermal reaction in a mixture of DMF and EtOH. Postsynthetic modification of DUT-71 using different neutral nitrogen-containing bridging molecules in a single-crystal to single-crystal transformation fashion results in a series of porous compounds (DUT-72, DUT-73a, DUT-73b, DUT-74, DUT-90, DUT-91, and DUT-95) with apparent BET surface area up to 2700 m2 g–1. Interestingly, the Cu–Cu distances between paddle wheels during the transformation are adapted to the bridging ligands, demonstrating the flexible character of DUT-71. After solvent removal and resolvation, a drastic color change from green to dark blue and vice versa was observed. This observation was studied in detail in situ by monitoring the adsorption of ethanol in the low-concentration region by UV/vis analysis. The correlation between the ethanol adsorption upta...