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Chemical transformations of a crystalline coordination polymer: a multi-stage solid–vapour reaction manifold

DOI: 10.1039/c2sc21654j DOI Help

Authors: Iñigo J. Vitórica-yrezábal (The University of Sheffield) , Guillermo Mínguez Espallargas (Universidad de Valencia, Spain) , Janet Soleimannejad (University of Tehran, Iran) , Alastair Florence (University of Strathclyde) , Ashleigh J. Fletcher (Department of Chemical and Process Engineering, University of Strathclyde) , Lee Brammer (University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemical Science , VOL 4 (2) , PAGES 696–708

State: Published (Approved)
Published: November 2012

Abstract: In its crystal structure the one-dimensional coordination polymer [Ag4(O2C(CF2)2CF3)4(TMP)3]n (1) (TMP = 2,3,5,6-tetramethylpyrazine) adopts a zig-zag arrangement in which pairs of silver(I) centres bridged by two fluorocarboxylate ligands are linked alternately via one or two neutral TMP ligands. This material can reversibly absorb/desorb small alcohols (ROH) in single-crystal-to-single-crystal transformations, despite the lack of porosity in the crystals, to yield a related material of formula [Ag4(O2C(CF2)2CF3)4(TMP)3(ROH)2]n (1-ROH). The absorption process includes coordination of the alcohol to silver(I) centres and, in the process, insertion of the alcohol into one-quarter of the Ag-O bonds of coordination polymer. When in place, the alcohol molecule is also supported by formation of an O-H...O hydrogen bond to the now partially dissociated carboxylate group. The reverse process leading to desorption of the alcohol takes place upon mild heating to regenerate 1. Upon further heating, 1 can release molecules of TMP into the vapour phase resulting in a separate chemical and structural transformation to yield a two-dimensional layered material of composition [Ag4(O2C(CF2)2CF3)4(TMP)2]n (2). This new transformation occurs via dissociation of Ag-N bonds upon ligand release and formation of new Ag-O bonds. The whole series of transformations has been followed in situ by single-crystal and/or powder X-ray diffraction and studied by thermogravimetric analysis. As a mechanistic probe to explore transport within formally nonporous 1, gravimetric CO2 gas sorption/desorption has been conducted. It is proposed that transport of small molecules occurs through the fluorous layers in the crystal.

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction

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