Dipodal quinoline-tethered fluorescent probe synthesis and investigation of spectroscopic properties

Abstract Novel quinoline-tethered fluorescent probe was designed and synthesized as multidentate ligand. Their sensing actions were confirmed by UV–Vis absorbance and emission spectroscopic studies in presence of perchlorate salts of Co 2+ , Li + , Fe 2+ , K + , Pb 2+ , Cu 2+ , Zn 2+ , Ni 2+ , Hg 2+ , Ag + cations in acetonitrile (1 × 10 −5  M for absorption studies, 1 × 10 −7  M for fluorescence studies). It was found that the dipodal compounds can selectively bind to Cu 2+ and Ag + metal ions with a significant quenching in their emissions. The capture of Cu 2+ and Ag + by the probe resulted in deprotonation of the secondary amine conjugated to the quinoline-tethered probe, so that the electron-donation ability of the ‘N’ atom would be greatly enhanced and the probe (2) showed blue-shift in emission and exhibited an on-off fluorescent response. The binding study was explored by using fluorescence spectroscopy with Job plot method.