Promising ESIPT-based fluorescence sensor for Cu²⁺ and CN⁻ ions: investigation towards logic gate behaviour, anticancer activities and bioimaging application

Abstract

An excited state intramolecular proton transfer (ESIPT) process-based novel chromogenic and fluorogenic probe (2) was synthesized with the aim of sequential in situ detection of Cu2+ and CN− ions under aqueous and biological conditions.

A Highly Selective “On‐Off‐On” Optical Switch for Sequential Detection of Cu2+and S2−Ions Based on 2, 6‐Diformyl‐4‐methyl Phenol and Catecholase Activity by Its Copper Complex

“…From Figure , it is evident that while receptor HL strongly interacts with Cu 2+ ion and displays quenching of emission, other co‐existing metal ions caused insignificant changes in the emission intensity of the receptor HL (Figure b). Coordination of Cu 2+ involving the imine nitrogen atom inhibits the ESIPT which resulted in steady decrease in the emission at 595 nm ,. In the interaction process, upon addition of Cu 2+ (5 equiv), the system exhibited significant quenching in the fluorescence intensity (Φ=0.015) with an observable colour change of the solution from reddish orange to non fluorescent under UV‐illuminescence (Figure ).…”

A Fluorogenic Triphenyl‐Amine‐Naphthyl‐Hydrazide Probe Selective for Cu2+ and Cysteine Detection via an ON‐OFF‐ON Logic path with Real Applications

“…H 2 L may exist in keto and enol form which may exhibit emission at two different wavelengths; 540 and 570 nm respectively. The proton transfer may assist imine‐phenol to keto‐amine tautomerisation [41–45] . (Scheme S2) The probe H 2 L in solution phase exhibits only single band at 550 nm.…”

“…The proton transfer may assist imine-phenol to keto-amine tautomerisation. [41][42][43][44][45] (Scheme S2) The probe H 2 L in solution phase exhibits only single band at 550 nm.…”

“…( Figure S12) which is fairly less than the recommended permissible limit for Cu 2 + (20 μM) in drinking water by WHO. [7] The reports are available for Cu 2 + sensing using different fluorogenic sensors like pyrene appended imine-phenol (LOD,1.21 μM in CH 3 CN/HEPES Buffer), [7] Coumarin-napthol probe (LOD, 12.7 nM in DMSO/HEPES buffer), [14] Rhodamine-benzothiazole (LOD, 6.89 μM in CH 3 CN/water), [20] pyrrole appended chromen-ol (LOD, 0.512 μM in DMSO/PBS buffer) [45] , naptholhydrazide (LOD, 223 nM in PBS buffer) [46] and dicyanomethylene-4H-pyran picolinate derivative (LOD, 23 nM in DMSO/PBS Buffer); [49] The present probe H 2 L shows better efficiency (LOD, 7.3 nM). Hence, the probe is applicable and suitable for detection of Cu 2 + in trace quantity.…”