• Florence, Alastair
• Fletcher, Ashleigh
• Vitorica-Yrezabal, Iñigo
• Brammer, Lee
• Espallargas, Guillermo Mínguez
• Soleimannejad, Janet

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) centers bridged by two fluorocarboxylate ligands are linked alternately via one or two neutral TMP ligands. This material can reversibly absorb 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 process involves coordination/dissociation of the alcohol to/from the silver (I) centers and, in the process, insertion/deinsertion 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 partially dissociated carboxylate group. Upon further heating, 1 can release molecules of TMP into the vapor 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.

Topics

• impedance spectroscopy
• polymer
• single crystal
• silver
• phase
• layered
• powder X-ray diffraction
• Hydrogen
• thermogravimetry
• two-dimensional
• porosity
• alcohol
• one-dimensional