Modulating supramolecular binding of carbon dioxide in a redox-active porous metal-organic framework.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28194014.
- Also identified by DOI 10.1038/ncomms14212 and PMC identifier 5316804.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Hydrogen bonds dominate many chemical and biological processes, and chemical modification enables control and modulation of host-guest systems. Here we report a targeted modification of hydrogen bonding and its effect on guest binding in redox-active materials. MFM-300(V<sup>III</sup>) {[V<sup>III</sup><sub>2</sub>(OH)<sub>2</sub>(L)], LH<sub>4</sub>=biphenyl-3,3',5,5'-tetracarboxylic acid} can be oxidized to isostructural MFM-300(V<sup>IV</sup>), [V<sup>IV</sup><sub>2</sub>O<sub>2</sub>(L)], in which deprotonation of the bridging hydroxyl groups occurs. MFM-300(V<sup>III</sup>) shows the second highest CO<sub>2</sub> uptake capacity in metal-organic framework materials at 298 K and 1 bar (6.0 mmol g<sup>-1</sup>) and involves hydrogen bonding between the OH group of the host and the O-donor of CO<sub>2</sub>, which binds in an end-on manner, =1.863(1) Å. In contrast, CO<sub>2</sub>-loaded MFM-300(V<sup>IV</sup>) shows CO<sub>2</sub> bound side-on to the oxy group and sandwiched between two phenyl groups involving a unique ···c.g.<sub>phenyl</sub> interaction [3.069(2), 3.146(3) Å]. The macroscopic packing of CO<sub>2</sub> in the pores is directly influenced by these primary binding sites.