Fluorescent ratioable recognition of Cu2+ in water using a pyrene-attached macrocycle/(gamma)cyclodextrin complex

A pyrene-functional fluoroionophore, 1 was used to construct a supramolecular 1/(gamma)-CD complex for Cu2+ recognition in water. In aqueous (gamma)-CD solution, 1 exhibits pyrene monomer fluorescence emission at 378 nm and 397 nm, while in the presence of Cu2+, it shows a pyrene excimer emission at 452 nm with a decrease in the monomer fluorescence due to the formation of a 1:2 metal–liganded complex. Based on the response characteristics of the supramolecular complex, a fluorescent ratiometric method was performed for the determination of Cu2+ concentration in water. With the optimum conditions described, Cu2+ in aqueous solution can be determined from 1.2 × 10^-6 to 4.5 × 10^-4 M. The Cu2+ selectivity of the complex is excellent, and the excimer fluorescence enhancements are very smaller induced by other heavy metal and transition metal ions.