Synthesis and evaluation of the chromo-fluorogenic recognition ability of imidazoquinoline derivatives toward ions

Abstract

Four imidazoquinolines functionalized with different carbocycles and heterocycles have been synthesized and characterized. Acetonitrile solutions of the four receptors presented absorption bands in the 330-370 nm range. The four probes were also emissive with fluorescence bands in the 390-460 nm interval. In a first step, the chromo-fluorogenic behaviour of the four probes was evaluated in the presence of selected anions. Addition of F- induced the appearance of a new red-shifted absorption band together with a moderate quenching of the fluorescence in all four receptors. In a second step, the UV-visible and emission behaviour of the four receptors in the presence of cations was tested. Addition of Hg2+, Cu2+, Co2+, Fe3+, Fe2+, Zn2+, Pb2+, Cd2+, Cr3+ and Al3+ induced a similar optical change in all four receptors (appearance of a broad red-shifted absorption band together with a remarkable quenching of the emission band).