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

An efficient fluorescent Al3+ sensor, 2-hydroxy-1-naphthylaldehyde nicotinoyl hydrazone (HL) has been designed and synthesized. The receptor shows off-on fluorescent responses toward Al3+ in near 100% aqueous media. Other relevant metal ions such as Li+, Na+, K+, Ca2+, Mg2+, Cu2+, Co2+, Mn2+, Ni2+, Zn2+, Ba2+, Fe2+, Cd2+, Hg2+, Pb2+, Sc3+, Fe3+, Cr3+ caused almost no fluorescence increase. The reason for this phenomenon is that the addition of Al3+ to the solution of HL induce the formation of a 1:1 stoichiometry of the binding mode of L-Al(III) which inhibits the excited-state intramolecular proton transfer (ESIPT) and photoinduced electron transfer (PET). More importantly, the reversibility of the recognition process of HL was performed by adding a Al3+ bonding agent Na(2)EDTA. (C) 2015 Elsevier B.V. All rights reserved.