| Autor: |
Xiao DJ, Gonzalez MI, Darago LE, Vogiatzis KD; Department of Chemistry, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States., Haldoupis E; Department of Chemistry, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States., Gagliardi L; Department of Chemistry, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States., Long JR; Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2016 Jun 08; Vol. 138 (22), pp. 7161-70. Date of Electronic Publication: 2016 May 26. |
| DOI: |
10.1021/jacs.6b03680 |
| Abstrakt: |
The air-free reaction of CoCl2 with 1,3,5-tri(1H-1,2,3-triazol-5-yl)benzene (H3BTTri) in N,N-dimethylformamide (DMF) and methanol leads to the formation of Co-BTTri (Co3[(Co4Cl)3(BTTri)8]2·DMF), a sodalite-type metal-organic framework. Desolvation of this material generates coordinatively unsaturated low-spin cobalt(II) centers that exhibit a strong preference for binding O2 over N2, with isosteric heats of adsorption (Qst) of -34(1) and -12(1) kJ/mol, respectively. The low-spin (S = 1/2) electronic configuration of the metal centers in the desolvated framework is supported by structural, magnetic susceptibility, and computational studies. A single-crystal X-ray structure determination reveals that O2 binds end-on to each framework cobalt center in a 1:1 ratio with a Co-O2 bond distance of 1.973(6) Å. Replacement of one of the triazolate linkers with a more electron-donating pyrazolate group leads to the isostructural framework Co-BDTriP (Co3[(Co4Cl)3(BDTriP)8]2·DMF; H3BDTriP = 5,5'-(5-(1H-pyrazol-4-yl)-1,3-phenylene)bis(1H-1,2,3-triazole)), which demonstrates markedly higher yet still fully reversible O2 affinities (Qst = -47(1) kJ/mol at low loadings). Electronic structure calculations suggest that the O2 adducts in Co-BTTri are best described as cobalt(II)-dioxygen species with partial electron transfer, while the stronger binding sites in Co-BDTriP form cobalt(III)-superoxo moieties. The stability, selectivity, and high O2 adsorption capacity of these materials render them promising new adsorbents for air separation processes. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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