Cyclams Bearing Diametrically Disubstituted Pyrenes as Cu2+- and Hg2+-Selective Fluoroionophores

Abstract

New cyclam derivatives having diametrically disubstituted pyrene fluorophores were prepared and their fluoroionophoric properties toward transition metal ions were investigated. The compounds exhibited significant selectivity toward Hg²⁺ and Cu²⁺ ions in switching-off type responses in aqueous methanol or acetonitrile solution. Dipyrene-diamide derivative 3, having extra binding sites of the amide function, exhibited more pronounced chemosensing behavior toward Hg²⁺ and Cu²⁺ ions than its parent, dipyrene derivative 2. Detection limits for the analysis of Hg²⁺ and Cu²⁺ ions of dipyrene-diamide derivative 3 were 1.45 × 10^-6 and 1.30 × 10^-6 M, respectively. The diametrically disubstituted dipyrene-cyclam 2 may be utilized as a new starting platform for the design of other supramolecular fluorescent signaling systems having switching or chemosensing behaviors toward transition metal ions.