AIEE Active Azomethine-Based Rhodamine Derivative For Ultrasensitive Multichannel Detection of Au Through a Fluorimetrically, Electrochemically, and RGB-Based Sensing Assay.

In this study, a novel rhodamine-based optically and electrochemically active chemosensor, integrated with a p-DMAC moiety, demonstrated extremely selective identification of Au ions relative to other metal species, including (Li, Na, K, Ba, Ca, Mg, Co, Mn, Zn, Pb, Ni, Fe, Hg, Fe, Cd, Pd, Al, Cr, Cu, and nitrate salt of Ag). These compounds demonstrated a novel and outstanding aggregation-induced emission enhancement (AIEE) behavior by aggregating in DMF/HO medium. Furthermore, the degree of quenching was varying linearly with a Au concentration from 0 to 40 nM, with a lower detection limit by RH-DMAC nanoaggregates of 118.79 picomolar (40.35 ppm). The Stern-Volmer plots, Job's plot, Benesi-Hildebrand plot, H NMR titrations, ESI-mass, and FTIR all revealed significant interactions between the sensor and Au. Moreover, the proposed electrochemical sensor afforded a linear correlation before the peak current and concentration of Au in the range of 0-40 nM, with a detection limit of 483.73 pM or 164.36 ppt (by cyclic voltammetry method) and 298.0 pM or 101.24 ppt (by the Differential Pulse Voltammetry method). Furthermore, the proposed sensing assay was used to measure Au ion in spiked water samples (tap, drinking, waste, and river water), achieving acceptable accuracy and precision with high recovery rates. Furthermore, RH-DMAC-coated fluorescence paper test strips were designed for on-site Au detection. Apart from this, the use of smartphone-based RGB (Red Green Blue) color analysis shortened the operating process, accelerated the detection technique, and provided a novel methodology for the instantaneous, real-time examination of Au in real water samples.