Recognition of Al3+ based on a naphthalene-based “Off-On” chemosensor in near 100% aqueous media

The sensor shows “turn-on” fluorescent responses toward Al3+ in near 100% aqueous media. The reason for this phenomenon is that the addition of Al3+ to the solution of HL result in the formation of a 1:1 stoichiometry of the binding mode of L-Al which inhibits the excited-state intramolecular proton transfer (ESIPT) and photoinduced electron transfer (PET).