Sensitive and Selective in Vitro Recognition of Biologically Toxic As(III) by Rhodamine Based Chemoreceptor

Arsenic induced cleavage of the spirolactam ring of a cleft shaped electronically enriched rhodamine based chemoreceptor molecule 3′,6′-bis(ethylamino)-2-((2-hydroxy-5-methylbenzylidene)amino)-2′,7′-dimethylspiro[isoindoline-1,9′-xanthen]-3-one (PBCMERI-23) has been reported in the present work. The developed easy, instant and economic luminescent probe instigate toward unlocking the selectivity for a specific lethal water contaminant such as As(III) from aqueous media up to a level of 0.164 ppb (beyond the critical limit of the World Health Organization). PBCMERI-23 displays a 2-fold optical response (chromogenic, colorless to reddish pink; fluorogenic, non-blooming fluorescence to yellow emission) via the ring opening phenomenon of the developed chemoreceptor. Owing to the remarkable photophysical and structural properties of the synthesized probe, the recognition event has been turned on in the low energy region. Detailed experimental techniques further supported by theoretical evidence establishes the plausible mechanistic course of the host:guest interaction. The spectrophotometric response of the developed chemoreceptor PBCMERI-23 turns out to be reversible with incremental addition of a stoichiometric amount of I–. The optical recognition phenomenon has been further synchronized and interfaced with molecular logic gate to molecular electronics. To explicate the bioapplicability of PBCMERI-23, varying cell lines, viz., pollen grains of Allamanda puberula (Aapocynaceae), radiator plant (Peperomia pellucida), Poecilia reticulata, Danio rerio, and squamous epithelial cells have been monitored. The probe displays sparkling yellow illumination when the cells were visualized under fluorescence microscope, which confirms its cell permeability and is a biomarker toward intracellular investigation and bio-imaging of As(III). Furthermore, the chemoreceptor has enormous capability in detecting As(III) from a series of wastewater specimens with varying pH, which makes the present chemoreceptor PBCMERI-23 unique of its kind.