Background:
The traditional methods for the detection and quantification of Cu2+ and Fe3+ heavy metal ions, are usually troublesome in terms of high–cost, non–portable, time–consuming, specialized personnel and complicated tools, so their applications in practical analyses is limited. Therefore, the development of cheap, fast and simple–use techniques/instruments with high sensitivity/selectivity for the detection of heavy metal ions are highly demanded and studied.
Methods:
In this study, a fluorene–based fluorescent ''turn–off'' sensor, methyl 2–(2–((((9H–fluoren–9–yl)methoxy)carbonyl)amino)–3– phenylpropanamido) acetate (probe FLPG) was synthesized via one–pot reaction and characterized by 1H–NMR, 13C–APT–NMR, HETCOR, ATR–FTIR and elemental analysis in detailed. All emission spectral studies of the probe FLPG have been performed in CH3CN/HEPES (9/1, v/v, pH=7.4) media at rt. The quantum (Φ) yield of probe FLPG decreased considerably in the presence of Cu2+ and Fe3+. The theoretical computation of probe FLPG and its complexes were also performed using density functional theory (DFT). Furthermore, bio–imaging experiments of the probe FLPG was successfully carried out for Cu2+ and Fe3+ monitoring in living–cells.
Results:
The probe FLPG could sense Cu2+ and Fe3+ with high selectivity and sensitivity, and quantitative correlations (R2>0.9000) between the Cu2+/Fe3+ concentrations (0.0−10.0 equiv). The limits of detection for Cu2+ and Fe3+ were found as 25.07 nM and 37.80 nM, respectively. The fluorescence quenching in the sensor is managed by ligand–to–metal charge transfer (LMCT) mechanism. Job’s plot was used to determine the binding stoichiometry (1:2) of the probe FLPG towards Cu2+ and Fe3+. The binding constants with strongly interacting Cu2+ and Fe3+ were determined as 4.56×108 M-2 and 2.02×1010 M-2, respectively, via the fluorescence titration experiments. The outcomes of computational study supported the fluorescence data. Morover, the practical application of the probe FLPG was successfully performed for living–cells.
Conclusion:
This simple chemosensor system offers a highly selective and sensitive sensing platform for the routine detection of Cu2+ and Fe3+, and it keeps away from the usage of costly and sophisticated analysis systems.
DFT calculations and electrochemical studies on azulene ligands for heavy metal ions detection using chemically modified electrodes