Thiazolidine based differential chromo-fluorescent sensor for Cu2+ and CN− ions: Elaboration as logic devices

Thiazolidine based probe 1 has been synthesized for selective estimation of Cu2+ ions amongst other metal ions viz., Zn2+, Co2+, Ca2+, K+, Ni2+, Mn2+, Fe2+, Hg2+, Na+, Pb2+, Ba2+, Fe3+, Al3+, Cr3+. The probe 1 has opened new absorption channels at 300 nm and 500 nm in the presence of Cu2+ ions. The ratiometric response has been observed in the presence of Cu2+ ions due to emission quenching at 425 nm and enhancement at 485 nm that resulted in “ON-OFF-ON” type sensing. The probe 1 has been used to estimate Cu2+ ions between 50 nM and 15 µM, which is much lower than recommended by WHO in drinking water (30 µM). The probe 1 has also shown selective ratiometric absorption behavior towards CN− ions in CH3CN: H2O: 1:1. The ratiometric behavior of the probe 1 in the presence of Cu2+ and CN− ions has mimicked as XOR logic function at λem 485 nm and YES logic gate at λabs 300 nm. The sensing mechanisms of the probe 1 toward Cu2+ and CN− ions have been theoretically supported by DFT and TD-DFT calculations. Probe 1 has been used for its practical aplicability to sense Cu2+ and CN− through dip coating method.