KCS

A bispyrenyl-polyether system has been synthesized and investigated as a fluorescent chemosensor for metal ions. Fluorescence changes of bispyrenyl-polyether for Al³⁺ metal ion complexation are found to be different from those for heavy metal ion and divalent ions. In free ligand, excited at 343 nm, the absorption wavelength of the pyrene, it emits a strong excimer emission at around 480 nm with weak monomer fluorescence at 390 nm. On the contrary, the monomer emission at 390 nm increase when Al³⁺ was bound to ligand, because two facing pyrenes groups form a less overlapped excimer compared with that of free ligand. Among metal ions tested, Pb²⁺ and Co²⁺, known as a quenching metal ion, caused the fluorescence of bispyrenyl-polyether to be quenched both in monomer and particularly in excimer. The binding behaviors for metal ions and the synthetic scheme of ligand will be discussed more in detail.