A triphenylamine-based multifunctional fluorescent probe for Cu2+ and Zn2+ as well as mechanochromism and application in latent fingerprints

In this study, a new versatile fluorescent probe, YH (N, N-((1E, 1′E)-((phenylazanediyl)bis(4, 1-phenylene))bis(methanylylidene))di(picolinohydrazide)), was created and synthesized. YH demonstrated the capability to continuously detect Cu²⁺ and PO₄³⁻ in EtOH/HEPES solutions (95/5, V/V, HEPES = 10 mmol, pH = 7.4). Additionally, YH could function as a ratiometric fluorescent probe for identifying Zn²⁺. The interaction mechanisms among YH and Cu²⁺ as well as Zn²⁺ were elucidated through ¹H NMR titration, mass spectrometry, and FT-IR spectroscopy. Moreover, YH displayed aggregation-induced luminescence in methanol and water. Furthermore, the solid form of YH exhibited notable mechanochromism characteristics, transitioning from blue to green after grinding, and this process was reversible by ethanol vapor fumigation. Due to YH’s high sensitivity to mechanical stimuli, a starch @ YH composite was successfully developed for detecting latent fingerprints. Meanwhile, YH was utilized for detecting Cu²⁺ and Zn²⁺ in environmental water samples and was effectively employed with test papers for ion detection, demonstrating broad application prospect.