Modulating proton diffusion and conductivity in metal-organic frameworks by incorporation of accessible free carboxylic acid groups

Peter Rought, Christopher Marsh, Simona Pili, Ian P. Silverwood, Victoria García Sakai, Ming Li, Martyn S. Brown, Stephen P. Argent, Inigo Vitorica-Yrezabal, George Whitehead, Mark R. Warren, Sihai Yang, Martin Schröder

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16 Citations (Scopus)

Abstract

Three multi-carboxylic acid functionalised ligands have been designed, synthesised and utilised to prepare the new barium-based MOFs, MFM-510, -511, and -512, which show excellent stability to water-vapour. MFM-510 and MFM-511 show moderate proton conductivities (2.1 × 10-5 and 5.1 × 10-5 S cm-1, respectively) at 99% RH and 298 K, attributed to the lack of free protons or hindered proton diffusion within the framework structures. In contrast, MFM-512, which incorporates a pendant carboxylic acid group directed into the pore of the framework, shows a two orders of magnitude enhancement in proton conductivity (2.9 × 10-3 S cm-1). Quasi-elastic neutron scattering (QENS) suggests that the proton dynamics of MFM-512 are mediated by "free diffusion inside a sphere" confirming that incorporation of free carboxylic acid groups within the pores of MOFs is an efficient albeit synthetically challenging strategy to improve proton conductivity.

Original languageEnglish
Pages (from-to)1492-1499
Number of pages8
JournalChemical Science
Volume10
Issue number5
DOIs
Publication statusPublished - 2019

ASJC Scopus subject areas

  • Chemistry(all)

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