Experimental and theoretical studies of imidazole based chemosensor for Palladium and their biological applications

Abstract An imidazole derivative (probe L1) bearing a thiophene group was developed as an ON-OFF fluorescent chemosensor for palladium ions. The UV-Visible absorption and fluorescence spectral behavior of probe L1 towards various cations were investigated in HEPES buffer aqueous solution. The absorbance intensity of probe L1 considerably enhanced whereas the fluorescence emission intensity was quenched in the presence of Pd2+ ions, while the presence of other metal ions had no notable interference. The stoichiometry of the complex was determined using Job’s plot and a plausible recognition mechanism of probe L1 and Pd2+ is proposed. Density Functional Theory (DFT) calculations were used to study the electronic properties and to optimize the structure on the selectivity of Pd2+ ions and are correlated with the experimental results. The intracellular Pd2+ ion detection in living cells was performed using probe L1 on brine shrimp nauplii (Artemia salina) up to 20 µg/mL.