Acylhydrazone Functionalized Triphenylamine-Based Fluorescent Probe for Cu²⁺: Tunable Structures of Conjugated Bridge and Its Practical Application

Novel fluorescent probes were constructed for the convenient and rapid analysis of Cu²⁺ ions, taking advantages of the the triphenylamine backbone as chromophore and acylhydrazone group as the Cu²⁺ recognition site. Especially, probe T2 could act as a dual-channel probe towards Cu²⁺ through both fluorescent and colorimetric method. Through the fluorescent method, the detection limit of probe T2 was calculated to be as low as 90 nmol/L and there was a good linear relationship between the intensity change and the concentration of Cu²⁺ ions. By virtue of the two-phase liquid-liquid extraction method, probe T2 could be successfully applied in practical extraction and separation of Cu²⁺. Furthermore, by applying a "turn-off-turn-on" circle, compound T2 could act as a sensitive probe towards S^2- anions through the indirect approach and the detection limit of complex T2-Cu²⁺ for S^2- anion was found to be 110 nmol/L.