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

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

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.

Citation

Rought, P., Marsh, C., Pili, S., Silverwood, I. P., Sakai, V. G., Li, M., Brown, M. S., Argent, S. P., Vitorica-Yrezabal, I., Whitehead, G., Warren, M. R., Yang, S., & Schröder, M. (2018). Modulating proton diffusion and conductivity in metal–organic frameworks by incorporation of accessible free carboxylic acid groups. Chemical Science, 10(5), 1492-1499. https://doi.org/10.1039/c8sc03022g

• Journal Article Type: Article
• Acceptance Date: Nov 2, 2018
• Online Publication Date: Nov 2, 2018
• Publication Date: Nov 2, 2018
• Deposit Date: Dec 23, 2018
• Publicly Available Date: Jan 2, 2019
• Journal: Chemical Science
• Print ISSN: 2041-6520
• Electronic ISSN: 2041-6539
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 5
• Pages: 1492-1499
• DOI: https://doi.org/10.1039/c8sc03022g
• Keywords: General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/1417640
• Publisher URL: https://pubs.rsc.org/en/Content/ArticleLanding/2019/SC/C8SC03022G#!divAbstract
• Contract Date: Jan 2, 2019