Pseudo-crown ether III: Naphthalimide-Pd(II) based fluorogenic ensemble for solution, vapour and intracellular detection of amine and anti-counterfeiting applications

Abstract

A bis-naphthalimide based pseudo-crown ether as metal complex-based ensemble (DN-1 + Pd2+) is reported for the sensing of tris(2-aminoethylamine) (TAEA). The DN-1 moiety exhibited cyan blue fluorescence in solution and solid state (CIE plot) with high quantum yield (φ = 0.92). The DN-1 showed selective fluorescence quenching at 450 nm upon addition of Pd2+ ions, whereas ensemble showed revival of the fluorescence upon addition of TAEA owing to displacement of Pd2+ ions from the binding cavity due to higher binding affinity of TAEA for Pd2+ ions. The detection limit of DN-1 for Pd2+ is 0.1 µM and the ensemble for TAEA is 0.8 µM. The complexation–decomplexation mechanisms were supported by optical, NMR, DLS, CV and AFM studies. The DN-1 and ensemble were successfully utilized for the intracellular imaging of Pd2+ ions and TAEA, respectively, in MG-63 live cells. The ensemble was successfully utilized for fabrication of solution and SiNPs based test kits for the detection of TAEA in solution and vapour phase. The DN-1 was further employed as information security ink for the anti-counterfeiting applications and for fabrication of IMPLICATION logic gate.