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Coordination polymer flexibility leads to polymorphism and enables a crystalline solid–vapour reaction: a multi-technique mechanistic study
DOI:
10.1002/chem.201500514
PMID:
25962844
Authors:
Inigo
Vitorica
(The University of Sheffield)
,
Stefano
Libri
(University of Sheffield)
,
Jason
Loader
(University of Sheffield)
,
Guillermo
Minguez Espallargas
(Universidad de Valencia)
,
Michael
Hippler
(University of Sheffield)
,
Ashleigh J.
Fletcher
(University of Strathclyde)
,
Stephen
Thompson
(Diamond Light Source)
,
John E.
Warren
(University of Manchester)
,
Daniele
Musumeci
(New York University)
,
Michael D.
Ward
(New York University)
,
Lee
Brammer
(University of Sheffield)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Chemistry - A European Journal
, VOL 21 (24)
, PAGES 8799–8811
State:
Published (Approved)
Published:
June 2015

Abstract: Despite an absence of conventional porosity, the 1D coordination polymer [Ag4(O2C(CF2)2CF3)4(TMP)3] (1; TMP=tetramethylpyrazine) can absorb small alcohols from the vapour phase, which insert into AgO bonds to yield coordination polymers [Ag4(O2C(CF2)2CF3)4(TMP)3(ROH)2] (1-ROH; R=Me, Et, iPr). The reactions are reversible single-crystal-to-single-crystal transformations. Vapour-solid equilibria have been examined by gas-phase IR spectroscopy (K=5.68(9)×10−5 (MeOH), 9.5(3)×10−6 (EtOH), 6.14(5)×10−5 (iPrOH) at 295 K, 1 bar). Thermal analyses (TGA, DSC) have enabled quantitative comparison of two-step reactions 1-ROH12, in which 2 is the 2D coordination polymer [Ag4(O2C(CF2)2CF3)4(TMP)2] formed by loss of TMP ligands exclusively from singly-bridging sites. Four polymorphic forms of 1 (1-ALT, 1-AHT, 1-BLT and 1-BHT; HT=high temperature, LT=low temperature) have been identified crystallographically. In situ powder X-ray diffraction (PXRD) studies of the 1-ROH12 transformations indicate the role of the HT polymorphs in these reactions. The structural relationship between polymorphs, involving changes in conformation of perfluoroalkyl chains and a change in orientation of entire polymers (A versus B forms), suggests a mechanism for the observed reactions and a pathway for guest transport within the fluorous layers. Consistent with this pathway, optical microscopy and AFM studies on single crystals of 1-MeOH/1-AHT show that cracks parallel to the layers of interdigitated perfluoroalkyl chains develop during the MeOH release/uptake process.
Journal Keywords: Coordination Polymers; Gas-Phase Spectroscopy; In Situ Diffraction; Microscopy; Polymorphism; Porosity; Solid-State Reactions; Thermal Analysis
Subject Areas:
Chemistry,
Materials
Instruments:
I11-High Resolution Powder Diffraction
Other Facilities: SRS Daresbury station 9.8
Added On:
17/04/2015 18:23
Discipline Tags:
Chemistry
Materials Science
Inorganic Chemistry
Polymer Science
Technical Tags: