A Naked Eye and Turn‐On Fluorescence Detection of Zn²⁺ Ion by Imidazole‐Quinoline‐Based Fluorophore and Its Application in Live‐Cell Imaging

Abstract

A novel quinoline-imidazole hybrid conjugate chromophore, 2-(4,5-diphenyl-1H-imidazol-2-yl)-4-phenylquinoline (DIPQ), is designed, synthesized, characterized using NMR, ESI-MS and ESI-HRMS analyses and explored for its ability in detecting a range of biologically relevant cations. Among the various metal ions, DIPQ responds selectively to the addition of Zn 2 + with a change in color from colorless to pale yellow along with characteristic green fluorescence at 564 nm. Zn 2 + induced absorption and fluorescence changes of DIPQ are not affected by other commonly coexistent metal ions and anions. DIPQ-Zn 2 + binding interactions are thoroughly studied using NMR and MALDI-MS analyses. DIPQ is capable to detect Zn 2 + even at the nano-molar levels with a limit of detection (LOD) and limit of quantification (LOQ) of 2.7 × 10 À 8 M and 8.1 × 10 À 8 M, respectively. Sample matrices have trivial impact on the Zn 2 + detection ability of DIPQ. The quantitative results obtained from the DIPQ method are comparable with the ICP-OES method. Moreover, DIPQ has a wide pH range of operation, exhibited good cell permeability and low toxicity for biological applications. Furthermore, DIPQ is suitable to detect Zn 2 + ions present in biological tissues.

Synthesis, photophysics and two-photon absorption of imidazole-centred tripodal chromophores

“…Imidazole-centred tripodal molecules have found various applications as pharmacophores, 36 charge-transfer (CT) chromophores, 37 fluorophores, [38][39][40][41][42] molecular sensors capable of detecting various analytes such as F À , BF 4 À /ClO 4 À , Hg 2+ , Zn 2+ , cysteine or picric acid, [43][44][45][46][47][48][49][50][51] viscosity probes, 52 pH probes, 53,54 luminescent solar concentrators (LSCs), 55 emitters for organic light-emitting diodes (OLEDs) [56][57][58][59] and robust heterocycles for dye-sensitised solar cells (DSSCs). [60][61][62] Besides interesting linear optical properties, imidazole push-pull molecules have also been investigated for their nonlinear optical (NLO) activity.…”