Benzothiazolylhydrazone-Based Turn-on Fluorescent Probe for Detecting Cu2+: S-donor as a Cu2+-induced Fluorescence Quenching Inhibitor

Abstract

The fluorescent turn-on detection of metal ions is highly desirable for public health and environmental security. Herein, we report a rationally designed fluorescent probe (1) for the detection of Cu2+ synthesized by integrating 2-hydrazinylbenzothiazole with 3-acetyl-7-hydroxycoumarin. The probe alone is non-fluorescent due to the isomerization of C=N in the excited state. The addition of Cu2+ can cause a delayed fluorescence enhancement. A comparative study of 1 and its analogues indicated that the turn-on fluorescence response was thanks to the sulfur atom coordinating to Cu2+. The response delay of 1 in sensing Cu2+ was ascribed to the gradual transition from N-coordination to S-coordination (N and S in thiazole moiety). The proposed new function of S-donor would provide a new approach for the turn-on fluorescence sensation of Cu2+.

Two novel coumarin-based fluorescent probes for the detection of Cu2+ and biological applications

“…In recent years, many small molecular fluorescent probes for detecting Cu ions have been developed. [14][15][16][17][18][19][20][21] However, most of them have shortcomings such as complex synthesis, low selectivity, and slow response time. It is well known that the key element of probe design is the ability of an excellently chosen fluorophore to combine with the detection group for specific recognition.…”