Sequential single-crystal-to-single-crystal vapochromic inclusion in a nonporous coordination polymer: unravelling dynamic rearrangement for selective pyridine sensing

Abstract

Beyond zeolites, alternative porous materials such as metal–organic frameworks (MOF) and covalent organic frameworks (COF) have provided a variety of materials with potential applications ranging from sensing to catalysis. However, less attention has been paid to nonporous materials acting in a porous fashion, probably because of the lack of structural data. Herein, we present the unprecedented selective solid–vapour sequential inclusion of pyridine in a nonporous Fe(II) coordination polymer. Even though this reorganization leads to a dramatic transformation of the initial 2D structure, through a 1D intermediate structure, to a 0D compound, these transformations remain single-crystal to single-crystal. Remarkably, pyrazine substitution is accompanied by a naked-eye colour change, and the process is reversible. In addition, this molecular process also takes place when the coordination polymer is embedded in a polymeric matrix.