Elucidation of Selectivity for Silver Ion Based on Metal-Induced H-Type Aggregation of Fluorescent Receptor.

In present work, a new substituted phthalonitrile derivative was prepared by the nucleophilic displacement reaction and then highly soluble zinc phthalocyanine (ZnPc) with four peripheral 1-hydroxyhexan-3-ylthio groups was synthesized by cyclotetramerization and characterized by FTIR, H and C NMRs spectroscopies, fluorescence and UV-vis measurements. The optical property and quantum yield of ZnPc were elucidated in mixed solvent of ethanol/water with varying compositions. The pH-dependent fluorescence and absorbance spectra of ZnPc in the absence and presence of Ag ions were obtained to elucidate the optimum pH value that is convenient for stable complex formation in predetermined mixture. A comparative study for recognition of Ag ion has been carried out to evaluate the effect of the solution parameters on selective sensing ability of ZnPc as a fluorescent receptor. Interference effect was investigated by spectrofluorometric titration based on fluorescence quenching of ZnPc upon addition of Ag ion in the presence of foreign metal ions. Stepwise complexation/decomplexation cycles with NaS-titration by fluorescence quenching/enhancement were investigated to establish the reversible response rate and reusability of ZnPc toward Ag ions. Graphical Abstract Selective determination of silver ion based on H-type aggregation of zinc phthalocyanine.