Smart-responsive luminescence and VOC sensing application of a copper(i) cluster with a novel P2CuI2CuN2 core†

Abstract

The detection of VOCs is of great significance due to their numerous applications in various fields, such as air quality assessment, environmental protection, and disease diagnosis. Herein, we report a smart-responsive luminescence device for detection of VOCs using a new CuI-cluster, (Xantphos)Cu₂I₂(4-PBO)₂ (1), as a probe. This cluster was characterized as a binuclear cluster structure with a novel P₂CuI₂CuN₂ core, which can be conveniently prepared using a ball-milling method. Owing to the high efficiency of the charge transfer transition from the cluster core to the peripheral 4-PBO ligand, the cluster emitted strong red light under both ultraviolet and visible light excitation. The luminescence mechanism was also elucidated through TD-DFT calculations. Furthermore, utilizing this cluster as a fluorescent probe, a paper-based sensor was successfully fabricated through a technical route involving polymer composite dispersion supported by a cellulose membrane. When exposed to a VOC atmosphere, the device demonstrated rapid and selective sensing responses, characterized by luminescence quenching (in the presence of cyclohexylamine) or enhancement, including vapochromic luminescence (in the presence of pyridine). A series of spectroscopic, structural, and theoretical investigations revealed that the fluorescence sensing operates through a reactive response mechanism.