Salicylideneimines as efficient dual channel emissive probes for Al3+: Harnessing ESIPT and ICT processes

Two simple fluorescent chemosensors (CS1 & CS2) based upon salicylideneimine derivatives were evaluated for their selective fluorescent sensing of Al3+. An attractive glowing green/blue colour was observed in the presence of Al3+ with dual channel emissions for CS1 (lambda(em) 499 & 535 nm) and CS2 (lambda(em) 485 & 515 nm) both. The inhibition of PET and C=N isomerization after Al3+ binding was responsible for the turn 'on' fluorescence response while the dual emissions were well justified in terms of ESIPT and ICT. The binding stochiometries between CS1/CS2 and Al3+ were found to be 1:1 and 2:1 respectively while the limit of detection (LOD) of Al3+ by CS1 was found to be similar to 10 times lower than that of CS2. (C) 2014 Elsevier B.V. All rights reserved.