Effect of metal substitution on polymorphism and flexibility of 1D coordination polymers
- 1Bernal Institute, Department of Chemical Sciences, University of Limerick Limerick V94T9PX Republic of Ireland
- 2Institute for Integrated Cell-Material Sciences, Kyoto University Institute for Advanced Study, Kyoto University Yoshida Ushinomiya-cho, Sakyo-ku Kyoto 606-8501 Japan
Abstract
Coordination polymers (CPs) can exhibit significant changes in properties when they adopt different polymorphs. Here, we show that metal substitution can alter the polymorphic outcome and framework stability of a one-dimensional (1D) CP. We report two packing polymorphs of a Cu(ii)-based CP, constructed from 1,3-bis(1H-imidazol-1-yl)benzene (bib, 1), namely polymorphs A and B of {[Cu(bib)2(H2O)][SiF6]}n, [SP-1-Cu-H2O][SIFSIX]-A and [SP-1-Cu-H2O][SIFSIX]-B, wherein extra-framework SiF62− (SIFSIX) anions are hydrogen-bonded to coordinated aqua ligands (H2O). The polymorphs comprise spiro (SP) loops arising from the bent conformation of the linker ligand (bib), but differ in the packing of their 1D chains. The methanol (MeOH) precursor of polymorph A, {[Cu(bib)2(CH3OH)2][SiF6]}n, [SP-1-Cu-2MeOH][SIFSIX]-A, crystallised concomitantly with [SP-1-Cu-H2O][SIFSIX]-B and converted to [SP-1-Cu-H2O][SIFSIX]-A on exposure to air, through a single-crystal-to-single-crystal replacement of methanol by water. Metal substitution from Cu(ii) to Zn(ii) afforded only one crystalline phase, [SP-1-Zn-2MeOH][SIFSIX]-A, which underwent a phase transformation to [SP-1-Zn-2H2O][SIFSIX]-A upon heating at 373 K under vacuum and subsequent exposure to air. Although the A polymorph of Cu(ii) was not stable to activation, the Zn(ii) analogue was successfully activated and analysed by gas (CO2 at 195 and 298 K) and vapour (water at 300 K) sorption. The insights presented herein demonstrate how metal substitution may affect polymorphic landscapes and alter the activation behaviour of 1D CPs.
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BibTeX
@article{koupepidou2026effect,
title = {{Effect of metal substitution on polymorphism and flexibility of 1D coordination polymers}},
author = {Kyriaki Koupepidou and Asif Raza and Tao He and Alan C. Eaby and Soumya Mukherjee and Michael J. Zaworotko},
journal = {Crystengcomm},
year = {2026},
month = nov,
doi = {10.1039/d6ce00723f},
url = {https://doi.org/10.1039/d6ce00723f},
note = {CC BY 3.0},
}
RIS
TY - JOUR
TI - Effect of metal substitution on polymorphism and flexibility of 1D coordination polymers
AU - Kyriaki Koupepidou
AU - Asif Raza
AU - Tao He
AU - Alan C. Eaby
AU - Soumya Mukherjee
AU - Michael J. Zaworotko
PY - 2026
DA - 2026/11/05
JO - Crystengcomm
DO - 10.1039/d6ce00723f
UR - https://doi.org/10.1039/d6ce00723f
AB - Coordination polymers (CPs) can exhibit significant changes in properties when they adopt different polymorphs. Here, we show that metal substitution can alter the polymorphic outcome and framework stability of a one-dimensional (1D) CP. We report two packing polymorphs of a Cu(ii)-based CP, constructed from 1,3-bis(1H-imidazol-1-yl)benzene (bib, 1), namely polymorphs A and B of {[Cu(bib)2(H2O)][SiF6]}n, [SP-1-Cu-H2O][SIFSIX]-A and [SP-1-Cu-H2O][SIFSIX]-B, wherein extra-framework SiF62− (SIFSIX) anions are hydrogen-bonded to coordinated aqua ligands (H2O). The polymorphs comprise spiro (SP) loops arising from the bent conformation of the linker ligand (bib), but differ in the packing of their 1D chains. The methanol (MeOH) precursor of polymorph A, {[Cu(bib)2(CH3OH)2][SiF6]}n, [SP-1-Cu-2MeOH][SIFSIX]-A, crystallised concomitantly with [SP-1-Cu-H2O][SIFSIX]-B and converted to [SP-1-Cu-H2O][SIFSIX]-A on exposure to air, through a single-crystal-to-single-crystal replacement of methanol by water. Metal substitution from Cu(ii) to Zn(ii) afforded only one crystalline phase, [SP-1-Zn-2MeOH][SIFSIX]-A, which underwent a phase transformation to [SP-1-Zn-2H2O][SIFSIX]-A upon heating at 373 K under vacuum and subsequent exposure to air. Although the A polymorph of Cu(ii) was not stable to activation, the Zn(ii) analogue was successfully activated and analysed by gas (CO2 at 195 and 298 K) and vapour (water at 300 K) sorption. The insights presented herein demonstrate how metal substitution may affect polymorphic landscapes and alter the activation behaviour of 1D CPs.
SN - 1466-8033
ER -