Aggregation-induced emission active salicylaldehyde hydrazone with multipurpose sensing applications

In this manuscript, the aggregation-induced emission (AIE) behaviour of a Schiff base salicylaldehyde hydrazone (SH) was investigated in DMSO-HEPES mixed solvents. The non-fluorescent SH in pure DMSO becomes a highly yellow-luminescent SH upon increasing the HEPES fraction >= 70 % in DMSO. The results of UV-vis, DLS, and SEM investigations supported the formation of SH self-aggregates, which inhibited the intramolecular rotation of SH and activated the excited state intramolecular proton transfer (ESIPT) mechanism to emit a bright yellow fluorescence at 535 nm. The AIEgen SH was applied for the sensing of cations, aldehydes, and nitroaromatics in HEPES buffer (5 % DMSO, 10 mM, pH 7.4) medium. The fluorescence of AIEgen SH was quenched by Cu2+, 2-hydroxy-5-nitrobenzaldehyde, and para-nitrophenol with a limit of detection of 3.74, 0.76, and 1.52 mu M, respectively, among the other tested metal ions, aldehydes, and nitroaromatics. The cotton buds coated with the AIEgen SH were designed for the qualitative visual detection of Cu2+. The AIEgen SH was also employed for the detection of Cu2+ in mung bean sprouts. Moreover, the AIEgen SH was used to quantify the selective analytes in a real environmental water sample. Additionally, the AIEgen SH was employed to make yellow fluorescent gel and to visualize latent fingerprints (LFPs) on a non-porous glass slide.

Automated summary

In this study, the aggregation-induced emission (AIE) behavior of a Schiff base salicylaldehyde hydrazone (SH) in DMSO-HEPES mixed solvents was investigated. The non-fluorescent SH in pure DMSO exhibited highly yellow-luminescent behavior when the HEPES fraction reached >= 70% in DMSO. UV-vis, DLS, and SEM investigations confirmed the formation of self-aggregates of SH, which inhibited intramolecular rotation and activated the excited state intramolecular proton transfer (ESIPT) mechanism for yellow fluorescence emission. The AIEgen SH was successfully applied for the sensing of cations, aldehydes, and nitroaromatics, as well as for the visualization of latent fingerprints.