NANODOMAINS HELP MOF BREATHE

A Breathing Zirconium Metal–Organic Framework with Reversible Loss of Crystallinity by Correlated Nanodomain Formation
B Beuken, F Vermoortele, M J Cliffe, M T Wharmby, D Foucher, J Wieme, L Vanduyfhuys, C Martineau, N Stock, F Taulelle, V Van Speybroeck, A L Goodwin, and D De Vos
Chemistry – A European Journal 22, 3264-3267 (2016)

The isoreticular analogue of the metal–organic framework UiO-66(Zr), synthesized with the flexible trans-1,4-cyclohexanedicarboxylic acid as linker, shows a peculiar breathing behavior by reversibly losing long-range crystalline order upon evacuation. The underlying flexibility is attributed to a concerted conformational contraction of up to two thirds of the linkers, which breaks the local lattice symmetry. X-ray scattering data are described well by a nanodomain model in which differently oriented tetragonal-type distortions propagate over about 7–10 unit cells.