Anil’s ultrasonic synthesis: A preliminary photophysical study of substituent’s effects on chromogenic and fluorogenic cation sensing

Abstract

Six new Anils A-F were sonochemically synthesized and their structural and photophysical properties were investigated by FTIR, 1H NMR, absorption and emission techniques yielding the molecular structures. Theoretical calculations were also performed under the DFT framework and its corresponding time-dependent counterpart. The Anils (E) and (F) were emissive in ethanol. Our photophysical results suggest the occurrence of proton transfer in the excited state (ESIPT) leading to a keto-enol non-balanced dual emission band in (B), (C) and (D) case. However, only Enol forms of E and F were present and emissive in solution. The fluorogenic and chromogenic sensing abilities of Anils towards Fe2+, Cr3+, Cu2+, Co2+, Mn2+, Ni2+ and Zn2+ ions were examined and exhibited specific multi-ion sensing response. The wise choice of substituents seems to tune chromogenic, and fluorogenic recognition responses owing to their specific electron donor–acceptor features. Among the synthesized Chemosensors, (B) presenting the most electronegative group, does not have the ability to detect any of the proposed cations. (A) shows only chromogenic responses for Cr3+ and Mn2+ while amino-pyridine derivatives (C) and (D) exhibit both chromogenic and fluorogenic effects. Iron ions tune both (E) and (F) fluorescence emission.