Solvent-dependent chromogenic sensing for Cu~(2+) and fluorogenic sensing for Zn~(2+) and Al~(3+): a multifunctional chemosensor with dual-mode

摘要

A new multifunctional chemosensor 1 was synthesized and characterized by spectroscopic tools along with a single crystal X-ray crystallography. It can exhibit selective recognition responses toward Cu~(2+), Zn~(2+) and Al~(3+) in different solvent systems with bimodal methods (colorimetric and fluorescence). This sensor 1 detected Cu~(2+) ions through a distinct color change from colorless to yellow in aqueous solution. Interestingly, the receptor 1 was found to be reversible by EDTA. The detection limit (11 μM) of 1 for Cu~(2+) is much lower than WHO guideline (30 μM) in drinking water. In addition, the sensor 1 showed significant fluorescence enhancements in the presence of Zn~(2+) ion and Al~(3+) ion in two different organic solvents (DMF and MeCN), respectively. The binding modes of the three complexes were determined to be a 1:1 complexation stoichiometry through Job plot, ESI-mass spectrometry analysis, and 1H NMR titration.