Pyridine-Based Gemini and Heterogemini Amphiphiles: Synthesis, Organogel Formation, Bioinspired Catalysis, Hydroxyl Ion Sensing, and Removal of Hazardous Pb(II) and Cd(II) Ions
Aparna Roy, Siddhartha Das, Meheboob Khan, Sumita Roy
Abstract
In this work, four pyridine-based gemini and hetero-gemini gelator molecules have been designed which demonstrated aggregate-induced enhanced emission (AIEE) after gel formation in a DMSO/DMF:H2O mixture. This AIEE effect was brought down after the addition of 0.01 M NaOH solution, but the AIEE intensity was regained after the addition of 0.01 M HCl solution. This occurrence makes an organogel to act as a hydroxyl ion sensor. The different characteristics of organogels were studied by numerous methods, for example, spectroscopy, rheology, X-ray diffraction, theoretical study, and SEM. These organogels have the ability to detect the toxic metal ions Pb(II) and Cd(II). The detection limit of the organogels has been found to be lesser than the permitted limit of Pb(II) and Cd(II) in water. In addition to the detection ability studied, organogels showed the absorbing and elution capacities of Pb(II) and Cd(II) ions. This efficacy implied that organogels can be utilized to detect and eliminate toxic metal ions from contaminated water. Besides this property, gelator molecules exhibit catecholase-type activity. The high rate of catalytic efficacy of the studied compounds was confirmed by high Kcat values. In this study, we first proposed that without the presence of any transition-metal atom, pyridine-based gelator molecules showed efficient catechol oxidase activity.