Boron‐Salphen Conjugate based Molecular Probe Exhibiting Fluorescence On‐Off‐On Response in Detection of Cu²⁺ and ATP through Displacement Approach

Abstract

Synthesis and photophysical properties of a fluorescent probe HBD is described. Probe upon interaction with metal ions, anions and nucleoside pyrophosphates (NPPs) showed fluorescence quenching with Cu2+ due to chelation enhanced quenching effect (CHEQ). Moreover, interaction of ensemble HBD.Cu2+ with anions and NPPs showed fluorescence “turn‐On” response with ATP selectively. “On–Off–On” responses observed with Cu2+ and ATP is attributed to an interplay between ESIPT and TICT processes. Cyclic voltammogram of probe exhibited quasi‐reversible redox behaviour with three oxidation and two reduction potentials and the change in band gaps of probe suggested the interaction with Cu2+ and ATP. The 2:1 and 1:1 binding stoichiometry for an interaction between probe and Cu2+ (LOD, 62 nM) and ensemble, HBD.Cu2+ with ATP (LOD, 0.4 µM) respectively are realised by Job’s plot and HRMS data. Cell imaging studies carried out to detect Cu2+ and ATP in HeLa cells. Also, the output emission observed with Cu2+ and ATP is utilized to construct an implication (IMP) logic gate. Test paper strips showed naked‐eye visible color responses to detect Cu2+ and ATP. In real water samples probe successfully detected copper (0.03 µM) between 5‐6.5 ppb level (ICP‐MS method).