Photophysical Investigation of a Benzimidazole Derivative and Its Applications in Selective Detection of Fe³⁺,...

The fluorescence based applications such as chemosensing of Fe³⁺ ion, temperature sensing, NOR-gate molecular logic operations, and fluorescent ink were achieved using an expired medicine namely Pantoprazole (sensor1) which is a derivative of benzimidazole class. The phenomenon of quenching was a basic principle used in sensing Fe³⁺. We found that there was a combined effect of dynamic and static processes in quenching of fluorescence of sensor1. To confirm the selectiveness of sensor1, we performed interference experiments with other metal ions. There was no interference between these metal ions and Fe³⁺. The low LOD value of 1.032 µM suggested that the molecule is highly sensitive towards Fe³⁺. A high quantum yield of 8.087% increased the possibility of using sensor1 for light applications. There was a 2:1 stoichiometric ratio between sensor1 and Fe³⁺. The FTIR data analysis confirmed the presence of functional groups S = O, C-O-C, etc. The average particle size found with the DLS method was 130.5 nm. The zeta potential of -12.7 mV indicated that sensor1 is quite stable in solution form. For logic gate application EDTA (Ethylenediaminetetraaceticacid) and Fe³⁺ were considered as inputs and fluorescence intensity was taken as an output. In thermal sensing application, the high value of activation energy i.e. 908 meV and relative sensitivity of 1.2% ⁰C^-1 affirmed that sensor1 can be used for thermal applications. The sensor1 was also apt for fluorescent ink application. Hence this investigation deduced that sensor1 can be a potential candidate for such applications over other conventional synthesized fluorescent probes.