Uncoordinated tetrazole ligands in metal–organic frameworks for proton‐conductivity studies

Abstract

Zr-based metal-organic frameworks (MOFs) were modified with pendant tetrazole ligands for proton conductivity studies. Although tetrazolate ligands coordinated to metal cations have been widely utilized to construct MOFs or porous coordination polymers, to date, the use of uncoordinated tetrazole groups in MOFs has been limited. In this study, a benzene-1,4-dicarboxylic acid with pendant tetrazole groups (BDC-N 4 ) was synthesized and used to prepare a Zr-based UiO-66 MOF using a mixed-ligand strategy. The tetrazolefunctionalized UiO-66-N 4 was compared to MOFs containing other acidic functional groups (hydroxyl, carboxylic acid, and sulfonic acid) with respect to their proton conductivities and acidities (calculated pK a ). Interestingly, UiO-66-N 4 showed a significant decrease in the activation energy with increase in the amount of added tetrazole groups, suggesting the Grotthuss proton conduction mechanism for uncoordinated tetrazole-containing MOFs.

Three isostructural MOFs based on different metal cations: proton conductivities and SC–SC transformation leading to magnetic changes

“…As far as we know, MOFs materials, which can promote the proton conductivity of composite membranes, usually possessed structural features such as continuous hydrogen bonding chains that can provide a proton transfer path, 48 hydrophilic groups or molecules that can absorb water molecules, 49 or acidic groups that can provide freedom proton. 50 For compounds 1–3 , their hydrogen bonds and hydrophilic molecules were the same because of the same structure. Four carboxylate groups of H 4 L ligand were deprotonated, as shown from the results of crystal structure analyses, there were no acidic groups in compounds.…”

Crystalline Metal‐Peptide Networks: Structures, Applications, and Future Outlook

“…[108][109][110][111] Yet the flexible nature of peptides is also a source of new discoveries, and the structural repertoires of MPNs are expected to expand further. Addressing these challenges will lead to the discovery of more sophisticated MPN functions, such as selective ion conductivity, [112][113][114] optoelectronic properties, [115][116][117][118] stimuli-responsiveness, [119][120][121] and catalytic activities. [122][123][124][125]…”

Synthetic approaches and electrocatalytic reactions of pristine metal–organic frameworks for energy conversion

“…1 Because of their high surface area and tunable pores, these materials have been explored in many applications such as gas storage/separation, catalysis, sensing, and magnetism. 2,3 MOFs are generally insulators because of the poor overlap (d–p orbitals) between the hard metal ions with the redox-inactive ligands through oxygen or nitrogen atoms. 4,5 The insulating nature of these materials limits their utility in several desirable technologies, such as fuel cells, batteries, supercapacitors and resistive sensing, and electronics.…”