A Cu2I2 cluster bearing MOF as a fluorescence sensing material for the visual detection of methanol

Abstract

Due to their wide applications concerning health and safety, sensitive and selective detection and distinguish of alcohol molecules, such as methanol in counterfeit wine, are of great importance. Fluorescence sensing materials towards probing alcohol molecules have been extensively developed based on their advantages of economical, convenient and rapid detecting properties. Herein, a fluorescent metal-organic framework (MOF) Cu2I2(pdc)4Sr4(DMF)6 (Sr-CuI-MOF, H2pdc = 3,5-pyridinedicarboxylic acid) featuring a three-dimensional (3D) structure is presented and characterized. Sr-CuI-MOF exhibits a thermally activated delayed fluorescence arising from the Cu2I2-pdc motif. By exposing to methanol, Sr-CuI-MOF shows a sensitive and selective fluorescence redshift, characterized by a pronounced solvatochromism. Consequently, Sr-CuI-MOF can accurately detect methanol by analyzing the linear relationship between the shift in emission wavelength or percentage of the fluorescence intensity quenching and the concentration of methanol. It represents the first CuI bearing MOF with fluorescence detecting of methanol. This work presents a novel approach to design visually fluorescent sensing MOFs by utilizing CuI-ligand motifs as building blocks and emission centers.