Fluorescent photoinduced electron transfer (PET) sensing molecules with p-phenylenediamine as electron donor

Fluorescent photoinduced electron-transfer sensors were made from p-phenylenediamine-substituted azacrown ethers attached with a dansyl group, in which the p-phenylenediamine moiety serves as electron donor and the dansyl group acts as the acceptor. Chelation-enhanced fluorescence was observed upon addition of metal salts. Selective fluorescence response was observed for Mg(2+) and/or Ca(2+) versus Na(+) and K(+) due to size match and charge density sensitivity of the p-phenylenediamine moiety.