Host–guest selectivity in a series of isoreticular metal–organic frameworks: observation of acetylene-to-alkyne and carbon dioxide-to-amide interactions

Humby, Jack D.; Benson, Oguarabau; Smith, Gemma L.; Argent, Stephen P.; da Silva, Ivan; Cheng, Yongqiang; Rudić, Svemir; Manuel, Pascal; Frogley, Mark D.; Cinque, Gianfelice; Saunders, Lucy K.; Vitórica-Yrezábal, Iñigo J.; Whitehead, George F. S.; Easun, Timothy L.; Lewis, William; Blake, Alexander J.; Ramirez-Cuesta, Anibal J.; Yang, Sihai; Schröder, Martin

Abstract

In order to develop new porous materials for applications in gas separations such as natural gas upgrading, landfill gas processing and acetylene purification it is vital to gain understanding of host-substrate interactions at a molecular level. Herein we report a series of six isoreticular metal-organic frameworks (MOFs) for selective gas adsorption. These materials do not incorporate open metal sites and thus provide an excellent platform to investigate the effect of the incorporation of ligand functionality via amide and alkyne groups on substrate binding. By reducing the linker length of our previously reported MFM-136, we report much improved CO2/CH4 (50:50) and CO2/N2 (15:85) selectivity values of 20.2 and 65.4, respectively (1 bar and 273 K), in the new amide-decorated MOF, MFM-126. The CO2 separation performance of MFM-126 has been confirmed by dynamic breakthrough experiments. In situ inelastic neutron scattering and synchrotron FT-IR microspectroscopy were employed to elucidate dynamic interactions of adsorbed CO2 molecules within MFM-126. Upon changing the functionality to an alkyne group in MFM-127, the CO2 uptake decreases but the C2H2 uptake increases by 68%, leading to excellent C2H2/CO2 and C2H2/CH4 selectivities of 3.7 and 21.2, respectively. Neutron powder diffraction enabled the direct observation of the preferred binding domains in MFM-126 and MFM-127, and, to the best of our knowledge, we report the first example of acetylene binding to an alkyne moiety in a porous material, with over 50% of the acetylene observed within MFM-127 displaying interactions (less than 4 Å) with the alkyne functionality of the framework.

Citation

Humby, J. D., Benson, O., Smith, G. L., Argent, S. P., da Silva, I., Cheng, Y., Rudić, S., Manuel, P., Frogley, M. D., Cinque, G., Saunders, L. K., Vitórica-Yrezábal, I. J., Whitehead, G. F. S., Easun, T. L., Lewis, W., Blake, A. J., Ramirez-Cuesta, A. J., Yang, S., & Schröder, M. (2018). Host–guest selectivity in a series of isoreticular metal–organic frameworks: observation of acetylene-to-alkyne and carbon dioxide-to-amide interactions. Chemical Science, 10(4), 1098-1106. https://doi.org/10.1039/c8sc03622e

• Journal Article Type: Article
• Acceptance Date: Oct 1, 2018
• Online Publication Date: Oct 12, 2018
• Publication Date: Oct 12, 2018
• Deposit Date: Dec 10, 2018
• Publicly Available Date: Dec 10, 2018
• Journal: Chemical Science
• Print ISSN: 2041-6520
• Electronic ISSN: 2041-6539
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 4
• Pages: 1098-1106
• DOI: https://doi.org/10.1039/c8sc03622e
• Keywords: General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/1395343
• Publisher URL: https://pubs.rsc.org/en/Content/ArticleLanding/2019/SC/C8SC03622E#!divAbstract
• Contract Date: Dec 10, 2018