A Highly Selective Fluorescent Chemosensor for Al3+ Based on 2,2':6',2''-Terpyridine with a Salicylal Schiff Base

Two 2,2':6',2''-terpyridine-based Schiff bases (TPySSB and TPySB) have been synthesized. The TPySSB shows remarkable selective ‘off-on’ fluorescence for Al3+ by photoinduced electron transfer (PET) mechanism of sensing. Chemosensor TPySSB binds Al3+ in a 1:2 ratio with an association constant 6.8×105 (R2=0.98) and this 1:2 stoichiometric model is established on Job’s plot and 1H NMR. Compared TPySSB and TPySB, it is of great importance of the existence of salicylidene unit due to its strong binding abilities of both phenol and C=N structure to the Al3+.