Target Analyte Interaction with a New Julolidine Coupled Benzoxazole‐based Dyad: A combined Photophysical, Theoretical (DFT), and Bioimaging Study

Abstract

AbstractA julolidine‐coupled benzoxazole‐based fluorescent chemosensor (BPOZ) is designed and developed to investigate the different target analyte interactions spectroscopically. Based on the ′off‐on‐off′ photoluminescence mechanism, the as‐prepared BPOZ is used for sequentially detecting Zn2+ and HSO4− ions, respectively. The UV‐visible absorption and photoluminescence spectral behavior is intramolecular charge transfer (ICT) in nature. When Zn2+ ions bind with BPOZ, its fluorescence is significantly enhanced at 512 nm due to chelation‐enhanced fluorescence. A green color emission is also visible under 365 nm UV light exposure, which is also confirmed by the color chromaticity diagram. Chelation‐enhanced photoluminescence is also manifested in the lifetime decay analysis. Further, it is well supported by different spectroscopic techniques and DFT analysis. In the presence of HSO4− ions, photoluminescence of the Zn2+ chelated BPOZ complex is significantly reduced, rebirthing the free BPOZ. The detection limit of BPOZ for Zn2+ and Zn2+ chelated BPOZ complex towards detecting Zn2+ and HSO4− ions is established to be in the order of nM and μM range, respectively, in the solution phase. Among the various explosive nitroaromatic compounds, picric acid (PA) quenched the emission of the Zn2+ chelated BPOZ complex, and the quenching mechanism is found to be both static and dynamic in nature. Using these chemically prearranged inputs and optical outputs, two inputs, INHIBIT, and three inputs, combinational logic gates have been constructed. The BPOZ chemosensor and Zn2+ chelated BPOZ complex are also employed to map Zn2+ ions and PA in the living cell. The performance of the BPOZ chemosensor and Zn2+ chelated BPOZ complex toward Zn2+ ions and PA proved that it could be exploited as a signal tool for environmental and biological samples.