Fluorescent ratioable recognition of Cu ²⁺ in water using a pyrene-attached macrocycle/γ-cyclodextrin complex

A pyrene-functional fluoroionophore, 1 was used to construct a supramolecular 1/γ-CD complex for Cu ²⁺ recognition in water. In aqueous γ-CD solution, 1 exhibits pyrene monomer fluorescence emission at 378 nm and 397 nm, while in the presence of Cu ²⁺, 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 Cu ²⁺ concentration in water. With the optimum conditions described, Cu ²⁺ in aqueous solution can be determined from 1.2 × 10 ^-6 to 4.5 × 10 ^-4 M. The Cu ²⁺ selectivity of the complex is excellent, and the excimer fluorescence enhancements are very smaller induced by other heavy metal and transition metal ions.