Highly Selective Turn-On Fluorogenic Chemosensor for Robust Quantification of Zn(II) Based on Aggregation Induced Emission Enhancement Feature

An incisively designed notable aggregation-induced emission enhancement (AIEE) active fluorescence probe, 1-(2-hydroxynaphthylmethylene)-2-(3-methoxy-2-hydroxybenzylidene) hydrazine (L), was synthesized via straightforward reaction from inexpensive reagents. It exhibited rapid response, superb selectivity, and swift sensitivity toward Zn2+ based on its promising CHEF/AIEE feature. L not only can sense Zn2+ through sharp colorimetric and selective turn-on fluorescence responses in DMF/H2O (9:1, v/v) medium, but also can distinguish between its significant AIEE activity in high water ratio and Zn2+ triggered AIEE activity through individual emission signals. Intriguingly, the AIEE properties of L may improve its impact. The molecules of L are aggregated into ordered one-dimensional rod-shaped microcrystals that show an optical waveguide effect. Job's plot from UV-vis absorption revealed the formation of L-Zn2+ complex with 1:1 stoichiometry. When bound with Zn2+ in 1:1 mode, enhanced turn-on emission was observed via chelation enhanced fluorescence through sensor complex (L-Zn) formation and excess addition of Zn2+, a vivid enhancement of fluorescence intensity over manifold through aggregate formation was observed. The entire process takes similar to 5 s, i.e., faster response time. The probe can detect Zn2+ as low as 1.1 x 10(-2) M. The AIEE mechanism of L and Zn2+ triggered AIEE mechanism were well established from fluorescence anisotropy, DLS, SEM, optical fluorescence microscope, time-resolved photoluminescence, and fluorescence reversibility study by adding Zn2+ and EDTA sequentially. Furthermore, the proposed analytical system with clear AIEE mechanism demonstrates a potential outlook for the on-site practical applications.