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Biomimetic O2 adsorption in an iron metal–organic framework for air separation† † Electronic supplementary information (ESI) available: Full experimental details, additional gas adsorption data and analysis, additional characterization data and analysis (Mossbauer spectroscopy, infrared spectroscopy, powder X-ray diffraction), and supplementary discussion. See DOI: 10.1039/c9sc06047b

ABSTRACT: Bio-inspired motifs for gas binding and small molecule activation can be used to design more selective adsorbents for gas separation applications. Here, we report an iron metal–organic framework, Fe-BTTri (Fe3[(Fe4Cl)3(BTTri)8]2·18CH3OH, H3BTTri = 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene), that binds O2 in a manner similar to hemoglobin and therefore results in highly selective O2 binding. As confirmed by gas adsorption studies and Mössbauer and infrared spectroscopy data, the exposed iron sites in the framework reversibly adsorb substantial amounts of O2 at low temperatures by converting between high-spin, square-pyramidal Fe(ii) centers in the activated material to low-spin, octahedral Fe(iii)–superoxide sites upon gas binding. This change in both oxidation state and spin state observed in Fe-BTTri leads to selective and readily reversible O2 binding, with the highest reported O2/N2 selectivity for any iron-based framework. Bio-inspired motifs for gas binding and small molecule activation can be used to design more selective adsorbents for gas separation applications.

SUBMITTER: Reed D

PROVIDER: S-EPMC8148054 | biostudies-literature |

REPOSITORIES: biostudies-literature

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