Stability and Hydrolyzation of Metal Organic Frameworks with Paddle-Wheel SBUs upon Hydration

Abstract

Instability of most prototypical metal organic frameworks (MOFs) in the presence of moisture is always a limitation for industrial scale development. In this work, we examine the dissociation mechanism of microporous paddle wheel frameworks M(bdc)(ted) 0.5 [M=Cu, Zn, Ni, Co; bdc= 1,4-benzenedicarboxylate; ted= triethylenediamine] in controlled humidity environments. Combined in-situ IR spectroscopy, Raman, and Powder x-ray diffraction measurements show that the stability and modification of isostructual M(bdc)(ted) 0.5 compounds upon exposure to water vapor critically depend on the central metal ion. A hydrolysis reaction of water molecules with Cu-O-C is observed in the case of Cu(bdc)(ted) 0.5 . Displacement reactions of ted linkers by water molecules are identified with Zn(bdc)(ted) 0.5 and Co(bdc)(ted) 0.5 . In contrast, . Ni(bdc)(ted) 0.5 is less susceptible to reaction with water vapors than the other three compounds. In addition, the condensation of water vapors into the framework is necessary to initiate the dissociation reaction. These findings, supported by supported by first principles theoretical van der Waals density functional (vdW-DF) calculations of overall reaction enthalpies, provide the necessary information for determining operation conditions of this class of MOFs with paddle wheel secondary building units and guidance for developing more robust units.

Electrocatalytic Metal–Organic Frameworks for Energy Applications

“…Many MOFs have shown instability in water,e speciallyu nder aqueous acidic/alkaline conditions. [66][67][68] Thisi nstabilityt ypically arises from weak metal-ligand coordinationb onds, particularly in the metal-oxide clusters, as these bonds are susceptible to hydrolysis, which leads to framework collapse. Additionally, open coordination sites leave the frameworks vulnerable to unwanted reactivity.B ecause MOFs have shown instability in aqueous media and molecular catalysts are knownt od ecompose during electrocatalytic testing, rigorous characterization of the MOFs following electrochemical testing is essentialt o assesst he stability of the MOF structure and to identify the active catalyst.…”

Finite-temperature properties of nonmagnetic transition metals: Comparison of the performance of constraint-based semilocal and nonlocal functionals

“…Importantly, it also captures the more general problem when nonlocal correlation forces compete with other types of forces [9], for example, giving rise to binding across important regions of low electron densities [10,14]. The method was expected to be relevant in first-principles DFT for both pure vdW problems including regular physisorption [49,[78][79][80], porous-materials gas absorption [81][82][83][84][85][86][87][88][89][90], and DNA base-pair interactions [91][92][93][94][95]. It was also quickly realized that truly nonlocal correlations affect materials descriptions much more broadly than what was perhaps originally anticipated [10,14,57,77,[96][97][98][99][100].…”

Structural, elastic, thermal, and electronic responses of small-molecule-loaded metal–organic framework materials

“…31,32 We have already successfully applied vdW-DF to investigate the adsorption of small molecules in MOFs and nano-structures in numerous other studies. 7,8,[33][34][35][36][37][38][39][40] Projector augmentedwave theory, 41,42 combined with a well-converged planewave cutoff of 600 eV, were used to describe the wave functions. The total energy was sampled on a 2×2×2 k -point grid, resulting in four irreducible k -points, necessary to fully converge the stress tensor.…”