A Luminescent Binuclear Cu(I) Complex Constructed by Bipyridine, Td-Dft Calculation, and its Fluorescent Sensing Properties for Vocs

Abstract

The design and research of materials with strong luminescence and fluorescence sensing for the detection of volatile organic compounds (VOCs) are of great significance and challenge. Herein, we report a binuclear Cu(I) complex, [Cu2(POP)2(MeCN)2(Bipy)](PF6)2 (2), which is synthesized rationally through a substitution reaction between complex [Cu(POP)(4-PBO)(MeCN)](PF6) (1) and Bipy lignand (POP is bis[2-(diphenylphosphino)phenyl]ether, Bipy is bipyridine, 4-PBO is 2-(4'-pyridyl)-benzoxazole). The complex 2 was characterized by single-crystal X-ray diffraction as an isolated binuclear structure constructed by a bridged Bipy ligand. Under UV light excitation, both the powder and doped thin film of 1 and 2 exhibit broadband photoluminescence emission. The TD-DFT calculation reveals the details of the electronic transitions corresponding to the light absorption and emission of the two complexes, and also illustrates that the improved luminescence of 2 compared to 1 is due to the T1 excited state transforms from a localized transition to a charge transfer transition similar to the S1 excited state and the extremely small energy gap ΔE(S1-T1) value of 0.09eV (2). Based on these complexes, fluorescent test strips were developed. It is gratifying to find that the test strip based 2 shows a distinguishable fluorescence response behavior to a variety of VOCs. Especially for acetophenone and acetonitrile, the test strip showed rapid quenching and rapid quenching followed by rapid enhancement of fluorescence response. Therefore, it can be used for rapid and highly selective fluorescence sensing detection of acetonitrile and acetophenone.

Keywords: binuclear Cu(I) complex, photoluminescence, fluorescent sensing, TD-DFT calculation, VOCs