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.
A dual-channel chromogenic and fluorogenic fused-aromatic-system-based chemoreceptor (2-(benzo[d]thiazol-2-yl)-1-((pyren-8-yl)methylene)hydrazine) (TyM) was designed for ditopic sensitivity towards heavy and transition metal ions (HTMs), such as Cu, in an aqueous medium and lethal CN in a semi-aqueous medium. The chemoreceptor displayed proclivity towards the targeted analytes with a distinct optical response (yellow to colourless in the case of Cu and yellow to bright red for CN). TyM formed a 2 : 1 adduct with Cu with a detection limit of 40 nM. A 1 : 1 binding stoichiometry was confirmed with the chemoreceptor TyM with CN in sub-nano molar limit of detection. In addition to sophisticated spectroscopic analysis, such as UV-vis, fluorescence, FTIR, H-NMR,C-NMR, ESI-MS, and HRMS, the plausible mechanistic course of sensing was also established from a theoretical perspective. The reversible UV-vis response of the chemoreceptor TyM towards CN and H can mimic different molecular logic functions and therefore can be exploited for designing several complex electronic circuits principally based on Boolean Algebra. In vitro fluorescence imaging in male microspores of seed plants (Bohonia Nigalandra) and Monilia Albicans (diploid fungus) with TyM and Cu confirmed the permeability of the chemoreceptor TyM at the cellular level as well as its ability to investigate transition metals, such as Cu, in biological samples.
A general synthesis of both acridines and acridinium ions is descried from inexpensive and commercially available aliphatic starting materials using iron as catalyst and aerobic oxygen as oxidant in alcoholic solvent to produce water as only by product.
Quinolin-2(1H)-ones are prevalent in natural products and pharmacologically useful compounds. Here we present an unconventional and hitherto unknown photocatalytic approach to their synthesis from easily available quinoline-N-oxides.
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