Benzothiazole-based chemosensor for CN− and Cu2+: multi-logic operations within a single molecule

A new benzothiazole azo dye colorimetric chemosensor for detecting Pb2+ ion

In this work, a new benzothiazole azo dye sensor (BTS) was synthesized, and its cation binding affinity was studied using the colorimetric method, UV-vis, and ¹H NMR spectral data. The results revealed that the sensor BTS exhibits a remarkable tendency for Pb²⁺ ion to perform spontaneous visual color change from blue (BTS) to pink (BTS + Pb²⁺), without any color change in the aqueous solutions of other cations such as Hg²⁺, Cu²⁺, Al³⁺, Ni²⁺, Cd²⁺, Ag⁺_, Ba²⁺, K⁺, Co²⁺, Mg²⁺, Na⁺, Ca²⁺, Fe²⁺, and Fe³⁺ ions. The observed selectivity could be due to the formation of the complex (BTS + Pb²⁺⁾, which led to a blue shift from 586 nm (BTS) to 514 nm (BTS + Pb²⁺) in the UV spectrum. The job's plot provided the stoichiometry ratio of the complex (BTS + Pb²⁺) to be 1:1. The limit of detection (LOD) of BTS for Pb²⁺ ion sensing was obtained at 0.67 µM. Additionally, the binding constant for BTS toward Pb ²⁺ ion was studied using the Benesi-Hildebrand equation. As a result of the BTS test paper strips investigations, it was found that the synthesized sensor BTS could be used as a rapid colorimetric chemosensor for the detection of the Pb²⁺ ions in the distilled, tap, and sea waters.

Fluorimetric Recognition of Nerve Agent Mimic Diethylchlorophosphate Along with Cu2+/Hg2+ Ions Using Imidazole Possessing Sensor

An imidazole possessing sensor (1) has been designed and developed by simple one step reaction and characterization was done by using common spectroscopic methods. The fluorimetric sensing of nerve agent mimic, DCP, was carried out by observing blue shift in spectra accompanied with quenching in semi-aqueous solvent. The sensor was found proficient for the detection of DCP amongst other phosphates with detection limit of 69 nM. Furthermore, upon incorporation of various metal ions to CH₃CN:H₂O (4:1, v/v) solution of 1 (λ_ex 340 nm), the fluorescent probe turned non-fluorescent only in presence of Cu²⁺/Hg²⁺ ions. This was accompanied by fluorescent color change from light blue to yellow in case of Hg²⁺ and colorless in case of Cu²⁺ ions. Moreover, practical applications of sensor 1 were investigated for recognition of Cu²⁺ and Hg²⁺ ions in real water samples along with the detection of DCP in soil samples from different areas. Differential emission changes observed with addition of Hg²⁺ ions and DCP led to observation of "NOR" and an "INHIBIT" molecular photonic logic operations at 446 and 385 nm, respectively.

Lansoprazole-Based Colorimetric Chemosensor for Efficient Binding and Sensing of Carbonate Ion: Spectroscopy and DFT Studies

The new benzimidazole based receptor Lansoprazole has been used to detect carbonate anion by naked-eye and Uv-Vis spectroscopy. This receptor revealed visual changes withCO 3 2 - anion in ethanol. No detectable color changes were observed upon the addition of any other tested anions. The lansoprazole chemosensor selectively recognizesCO 3 2 - ion over the other interference anions in the ethanol, followed by deprotonation and reflected 1:1 complex formation between the receptor and the carbonate ion. Lansoprazole exhibits splendid selectivity toward carbonate ion via a visible color change from colorless to yellow with a detection limit of 57 μM. The binding mode ofCO 3 2 - to receptor L is supported by Density Functional Theory calculation. Moreover, this receptor shows a practical visible colorimetric test strip for the detection of carbonate ions. The transition states calculation demonstrates the occurrence of reaction from L to L-CO 3 2 - after overcoming an energy barrier of 10.1 kcal/mol, and there is considerable interaction energy between L andCO 3 2 - (94.9 kJ/mol), both of which confirmed that receptor L has high sensitivity and selectivity to the carbonate ion. The theoretical studies were performed to acquire an electronic description of the complexation mechanism byCO 3 2 - as well as to study bonding and structure in the complex. The optimized structures and binding mechanisms were supported with a high correlation and agreement by spectroscopy and DFT calculations.

Dual chemosensor for the rapid detection of mercury(ii) pollution and biothiols

A new benzothiazole azo dye [(E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diol] (also known as “BAN”), has been synthesised and used as a chemosensor for the rapid and selective detection of mercury(ii) ions in water.

A reversible fluorescent-colorimetric chemosensor based on a novel Schiff base for visual detection of CO32− in aqueous solution

A novel Schiff base receptor L has been fabricated for fluorescent-colorimetric detection of CO₃²⁻ in aqueous media. L shows an excellent selectivity, rapid response and reversibility and its sensitivity for CO₃²⁻ is the lowest ever found (96 nM).