Conformation of Pyrenophanes and Pyrene–Crown Ether Linked Molecules and Their Application as Fluorescent Sensors

Abstract

Conformation and fluorescence properties of pyrenophanes and pyrene-crown ether linked compounds in the presence and absence of metal ions have been investigated. [3.3](1,3)Pyrenophanes were found to be molecules that are in equilibrium between syn and anti conformers and reversibly emits monomer and intramolecular excimer fluorescence depending on temperature and solvent polarity. The fluorescence colors of (1,3) and (1,8)pyrenophanes having crown ether moieties also change depending on the temperature and solvent polarity, but in addition, the addition of metal and dialkylammonium ions causes the fluorescence change from excimer to monomer emissions. The compounds in which pyrene and crown ethers are rigidly linked or fused significantly change the fluorescence intensity and monomer/excimer emission ratio depending on the presence or absence of metal ions.