Guest-selective shape-memory effect in a switchable metal-organic framework DUT-8(Zn).

Abstract

Crystal size engineering allows tailoring of flexible metal-organic frameworks (MOFs) to achieve new properties. The gating type flexibility of the DUT-8(Zn) ([Zn2(2,6-ndc)2(dabco)]n, 2,6-ndc = 2,6-naphthalene dicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane) compound is known to be extremely particle size sensitive. Here, the physisorption of ethanol vapor gives rise to so-called shape-memory effect, leading to rigidification and flexibility suppression. According to powder X-ray diffraction and nitrogen physisorption experiments, the open pore phase is retained selectively after desorption of alcohols, which could be attributed to the nano-structuring and surface deformation of the crystals as a result of exposure to alcohols.