A theoretical investigation of a series of zinc ion responsive fluorescent probes based on 8-aminoquinoline

A series of conjugated structured fluorescent probe molecules based on 8-aminoquinoline were designed and investigated in aqueous solution using a quantum chemical method. The results indicate that the absorption and fluorescence emission spectra (λA and λE) of the probe molecules generally show redshifts (45.6–71.8 and 59.0–127.0 nm, respectively) upon the coordination of Zn2+. Large Stokes shifts (7205.6–9655.0 cm−1) imply that the interference between λA and λE can be avoided for these molecules. The analysis of thermodynamic properties demonstrates that ligands L1, L5, L8 and L9 have better binding possibility for the zinc ion than cadmium ion. In addition, the investigation of photoinduced electron transfer (PET) mechanism indicates that the studied probe molecules will be hopeful to be good off–on fluorescent probe for zinc ion detection in aqueous solution.