Enhancement of CO₂ uptake and selectivity in a metal-organic framework by the incorporation of thiophene functionality

Bolotov, Vsevolod A., Kovalenko, Konstantin A., Samsonenko, Denis G., Han, Xue, Zhang, Xinran, Smith, Gemma L., McCormick, Laura J., Teat, Simon J., Yang, Sihai, Lennox, Matthew J., Henley, Alice, Besley, Elena, Fedin, Vladimir P., Dybtsev, Danil N. and Schröder, Martin (2018) Enhancement of CO₂ uptake and selectivity in a metal-organic framework by the incorporation of thiophene functionality. Inorganic Chemistry, 57 (9), 5074-5082. (doi:10.1021/acs.inorgchem.8b00138).

Abstract

The complex [Zn₂(tdc)₂dabco] (H₂tdc = thiophene-2,5-dicarboxylic acid; dabco = 1,4-diazabicyclooctane) shows a remarkable increase in carbon dioxide (CO₂) uptake and CO₂/dinitrogen (N₂) selectivity compared to the nonthiophene analogue [Zn₂(bdc)₂dabco] (H₂bdc = benzene-1,4-dicarboxylic acid; terephthalic acid). CO₂ adsorption at 1 bar for [Zn₂(tdc)₂dabco] is 67.4 cm³·g^-1 (13.2 wt %) at 298 K and 153 cm³·g^-1 (30.0 wt %) at 273 K. For [Zn₂(bdc)₂dabco], the equivalent values are 46 cm³·g^-1 (9.0 wt %) and 122 cm³·g^-1 (23.9 wt %), respectively. The isosteric heat of adsorption for CO₂ in [Zn₂(tdc)₂dabco] at zero coverage is low (23.65 kJ·mol^-1), ensuring facile regeneration of the porous material. Enhancement by the thiophene group on the separation of CO₂/N₂ gas mixtures has been confirmed by both ideal adsorbate solution theory calculations and dynamic breakthrough experiments. The preferred binding sites of adsorbed CO₂ in [Zn₂(tdc)₂dabco] have been unambiguously determined by in situ single-crystal diffraction studies on CO₂-loaded [Zn₂(tdc)₂dabco], coupled with quantum-chemical calculations. These studies unveil the role of the thiophene moieties in the specific CO₂ binding via an induced dipole interaction between CO₂ and the sulfur center, confirming that an enhanced CO₂ capacity in [Zn₂(tdc)₂dabco] is achieved without the presence of open metal sites. The experimental data and theoretical insight suggest a viable strategy for improvement of the adsorption properties of already known materials through the incorporation of sulfur-based heterocycles within their porous structures.

This record has no associated files available for download.

Contributors

Author: Laura J. McCormick

Download statistics