A dynamic, luminescent and entangled MOF as a qualitative sensor for volatile organic solvents and a quantitative monitor for acetonitrile vapour

Abstract

A new luminescent entangled (srs nets with two-fold interpenetration, linked via short Cu⋯Cu distances of ca. 2.8 Å) MOF, namely, [(CuCN)₃L·(guest)_x]_n (L = 2,6-bis((3,5-dimethyl-1H-pyrazol-4-yl)methyl)pyridine; x = 1 or 2), which contains microporous channels, is synthesized. This MOF material shows structural dynamics upon adsorption of various volatile organic solvent molecules, accompanied by reversible guest responsive colour changes of the fluorescence emission that are discernible by the naked eyes. The vacuated form of this material can also exhibit qualitative solvate-optical sensing behaviours toward various mixed solvents. Moreover, a quantitative real-time monitoring device is constructed that implements the determination of acetonitrile vapour pressure through optical response, which causes a drastic emission change from blue to yellow. The detailed structural elucidation provides structure–property understanding for the host–guest responsive dynamics.