Collective Breathing in an Eightfold Interpenetrated Metal–Organic Framework: From Mechanistic Understanding towards Threshold Sensing Architectures

Abstract

Functional materials that respond to chemical or physical stimuli through reversible structural transformations are highly desirable for the integration into devices. Now, a new stable and flexible eightfold interpenetrated three‐dimensional (3D) metal–organic framework (MOF) is reported, [Zn(oba)(pip)]n (JUK‐8) based on 4,4′‐oxybis(benzenedicarboxylate) (oba) and 4‐pyridyl functionalized benzene‐1,3‐dicarbohydrazide (pip) linkers, featuring distinct switchability in response to guest molecules (H2O and CO2) or temperature. Single‐crystal X‐ray diffraction (SC‐XRD), combined with density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulations, reveal a unique breathing mechanism involving collective motions of eight mixed‐linker diamondoid subnetworks with only minor displacements between them. The pronounced stepwise volume change of JUK‐8 during water adsorption is used to construct an electron conducting composite film for resistive humidity sensing.

Large breathing effect induced by water sorption in a remarkably stable nonporous cyanide-bridged coordination polymer

“…Therefore combined structural and sorption studies of 1Mn show that initial chemisorption of four water molecules opens the channels in its structure, which only then enables physisorption of the remaining water. Although similar water-induced gate-opening behaviour was previously reported for JUK-8, 80 SIFSIX-23-Cu 83 and the MIL-53 family, 51,95,96 to the best of our knowledge 1Mn constitutes the first case among non-reticular materials.…”

Large Breathing Effect Induced by Water Sorption in the Exceptionally Stable Nonporous Non-MOF Crystalline Material

“…Therefore combined structural and sorption studies of 1Mn show that initial chemisorption of four water molecules opens the channels in its structure, which only then enables physisorption of the remaining water. Although similar water-induced gate-opening behavior was previously reported for JUK-8, 86 SIFSIX-23-Cu 87 and the MIL-53 family, [88][89][90] to the best of our knowledge 1Mn constitutes the first case among non-reticular materials. 1Mn•8H2O shows marvelous stability during dehydration-rehydration cycling taking into account the accompanying huge unit cell volume variations.…”

Logic and Symbolism of Switchable Porous Framework Materials

“…Several MOFs with responsivity towards water have been reported. A more recent example of an eightfold interpenetrated MOF with distinct water responsivity has been reported by Roztocki et al 31 This example shows an adequate transfer of Freges original scheme. However, some adaption is required in order to represent A as a condition for B, in this example the stimuli are conditionally interrelated (A⇒B).…”

“…The underlying reason is the high temperature far from the respective boiling points. On the other hand, assuming hydrogen and oxygen form water at 298 K, the resulting water vapor will open the pore system (Figure9c) 31.…”