Synthesis, characterization of vanillin based colorimetric chemosensor for sensing of fluoride ions

Active Hydrogen Free, Z-Isomer Selective Isatin Derived "Turn on" Fluorescent Dual Anions Sensor

An efficient and anions fluorescence "on-off" sensor of 1-(prop-2-yn-1-yl)-3-(quinolin-3-ylimino)indolin-2-one (PQI) has been developed for the selective sensing of dual anions of F- and NO3- ions in aqueous medium. Active hydrogen and Lewis acidic binding sites free, Z- isomer of isatin based π-conjugated quinoline exhibited excellent sensing activity against F- and NO3- ions in UV light. The fluorescence turns on the process accomplished via the PET "on-off" mechanism. The interaction between probe molecule and anions is thought to be a non-covalent interaction of the low electron density covalently bonded N-methylene moiety of propargyl isatin (-N-CH2-) of probe molecule with F- ion and the terminal acidic proton of propargyl group of isatin (-C≡C-H) with NO3- ions. The modes of anions binding with PQI and plausible mechanisms are proposed by 1H and 13C NMR titrations. The selectivity of anions sensing may be offered by the bucked structure of the Z-isomer. The calculated association constant values for PQI and F- and NO3- are ions 2.5 × 104 M-1 and 2.2 × 103 M-1, respectively, indicating strong binding interaction between the PQI and anions. The association nature of anions and probes was analyzed by a Jobs plot and the finding indicates both F- and NO3- ions are in 1:1 complexation with PQI. The limit of detection (LOD) of the probe with F- and NO3- ions is calculated and is to be 6.91 × 10-7 M and 9.93 × 10-7 M, respectively. The proposed PQI fluorophore possesses a low limit of detection (LOD) for both F- and NO3- ions which is within the WHO prescribed detection limit.

A coumarin based Schiff Base: An effective colorimetric sensor for selective detection of F- ion in real samples and DFT studies

Chemosensors are molecular devices which react with target and give a visible signal, which is a degree of its sensitivity. Herein, a novel coumarin based Schiff Base has been synthesized for F^- ions detection. The chemosensor showed an intense color change upon the addition of F^- ions (light yellow to purple). The chemosensor has fewer effects of competing anions. The limit of detection is calculated as low as 1.1 × 10^-6 and the binding constant was determined as 1.61 × 10⁴. The job's plot confirmed 1:1 stoichiometry between chemosensor and F^- ion. The reverse reaction of chemosensor with MeOH is useful to construct a combinatorial logic circuit gates. The interaction mechanism of chemosensor was deliberated by ¹H NMR, FTIR, and DFT studies. Finally, the chemosensor was useful to detect F^- ions in tooth-paste sample and test strip is prepared for F^- ions detection.

Hexaphenylbenzene-based fluorescent probes for the detection of fluoride ions

Novel hexaphenylbenzene derivatives (HPB-1 and HPB-2) were synthesized and their sensing abilities were investigated.

Mitochondria-targeted acridine-based dual-channel fluorescence chemosensor for detection of Sn4+ and Cr2O72- ions in water and its application in discriminative detection of cancer cells

The goal of the present work was to fabricate a new low-cost, easy-to-prepare, dual-channel fluorescence chemosensor comprised of acridine-diphenylacetyl moieties (NDA) to enable remarkable Sn⁴⁺ detection in water and biological medium. The resulting NDA-Sn⁴⁺ complex was utilized for the distinguished identification of Cr₂O₇^2- ions from other anions and biomolecules. These investigations involve the absorption, fluorescence, and electrochemical methods for the detection of Sn⁴⁺ and Cr₂O₇^2- ions in pure water. The mechanism for NDA-mediated Sn⁴⁺ detection was experimentally determined by FT-IR, NMR titrations, mass (ESI) analyses, and DFT calculations. The obtained results indicate that the NDA chemosensor possessed excellent performance characteristics including good water solubility and compatibility, quick response time (less than 10 s), high sensitivity (Sn⁴⁺ = 0.268 μM and Cr₂O₇^2- = 0.160 μM), and selectivity against coexisting metals, anions, amino acids, and peptides. The chemosensor NDA induced negligible toxicity in live cells and was successfully utilized as a biomarker for the tracking of Sn⁴⁺ in human normal and cancer cells. More importantly, NDA demonstrates distinguished recognition of Sn⁴⁺ in human cancer cells rather than in normal live cells. Additionally, NDA was shown to act as a mitochondria-targeted probe in FaDu cells.