Naked Eye Chemosensor and In Vivo Chelating Activity of Iron (III) By Bromopyridine Quinoxaline (BPQ).

A wide variety of medical, biomedical, and industrial applications has been reported for quinoxalines derivatives. In this work, a novel quinoxaline derivative was designed and synthesized. Naked-eye and quantitative detection of Fe3+ among several cations were evaluated using UV-Vis spectroscopy. New chemosensor, 2,3-bis(6-bromopyridine-2-yl)-6-chloroquinoxaline named BPQ, showed a selective interaction for iron ion over other tested cations by changing color. Iron overloaded mice were prepared as a thalassemia model and then the effects of iron-chelating activities of BPQ were experienced. The job's plot methods determined the stoichiometric ratio of ligand to Fe3+ (1:1). The iron content in serum was evaluated by atomic absorption spectroscopy (AAS). Results showed significant differences (two-fold decrease in total iron and Fe3+) between the iron overloaded and BPQ (dose of 20 mgkg-1). The BPQ was identified as a ligand, which can be applied as a new chelator for decreasing the excess iron of blood.

Facile microwave-assisted synthesis of Ti3C2 MXene quantum dots for ratiometric fluorescence detection of hypochlorite.

A dual-channel "naked-eye" colorimetric and ratio fluorescent probe has been developed based on titanium carbide quantum dots for the detection of curcumin and hypochlorite (ClO-). The fluorescence emission of Ti3C2 MXene quantum dots (Ti3C2 MQDs) is in the range 350-600 nm, and the maximum emission peak is at 430 nm that overlaps with the UV absorption of curcumin at 430 nm to a large extent. This facilitates the fluorescence resonance energy transfer (FRET) between Ti3C2 MQDs and curcumin. When ClO- is added, the phenolic and methoxy groups of curcumin are oxidized to quinones, resulting in the restoration of the fluorescence of Ti3C2 MQD. In addition, the probe designed makes it easier to distinguish colors with the naked eye to detect curcumin and ClO-. The linear detection range of curcumin was 0.05-10 µM, and the detection limit was 20 nM. The linear detection ranges of ClO- are 25-150 µM and 150-275 µM, and the detection limit is 5 µM. This study is the first report on the determination of curcumin and ClO- based on Ti3C2 MQDs by dual-channel "naked-eye" colorimetric and ratio fluorescence method.

Three-Fold C 3-Symmetric Off-On Fluorescent Chemo-Sensors for Fluoride.

Three novel C 3-symmetric tris-salicylaldimine Schiff base based "off-on" fluorescence sensors have been designed and synthesized. The synthetic approach involves a simple imine bond (C = N) formation between 1,3,5-tris(4'-aminophenyl)benzene (TAPB) and 3,5-substituted salicylaldehydes. The presence of salicylaldehyde units on periphery of the tris-salicylaldimine Schiff bases masks the fluorescence of TAPB core. Interestingly, binding of fluoride ions to the salicylaldehyde units turns the fluorescence "on" in visible region. Fluoride ion detection limits for the present sensors have been calculated to be in the range of 0.17-3.0 ppm, which depends on the nature of the salicylaldehyde units.

A selective thioxothiazolidin-coumarin probe for Hg2+ based on its desulfurization reaction. Exploring its potential for live cell imaging.

Sensing the most toxic heavy metal (mercury) has attracted a lot of attention in recent years due to its extreme harmfulness to both human health and the environment. Thus, we reported herein the synthesis, spectroscopic and kinetic characterization, and biological evaluation of a new thioxothiazolidin coumarin derivative (ILA92), which undergoes a desulfurization reaction induced by mercuric ions (Hg2+). This process is the origin of a selective sensing of Hg2+ ions in aqueous solution by colorimetric and fluorescent methods. Furthermore, the probe showed great potential for imaging Hg2+ in living cells.

Metal ion chemosensors based on diaza-18-crown-6 coupling with azobenzene dye.

Novel naked-eye cation-selective chemosensors were developed from derivatives of diaza-18-crown-6 bearing one or two azobenzenes functionalized with o-acetic acid or p-nitro groups. The chromogenic acid and nitro derivatives exhibited solvatochromic effects with a majority of quinone-hydrazone tautomer in DMSO. The study of sensing properties of all molecules towards several metal ions showed that the one and two nitro-bearing N1 and N2 derivatives responded selectively to Cr3+ in MeCN with a color change from pink to colorless. They also showed selectivity for Hg2+ in DMSO with a color change from purple to light yellow. The detection limit of N1 and N2 that render visual difference to the naked eye are 0.21 ppm and 0.31 ppm for Cr3+ in MeCN, and 1.20 ppm and 1.00 ppm for Hg2+ in DMSO, while that obtained from 3σ method are 0.08 ppm and 0.03 ppm for Hg2+ in DMSO. These results demonstrate a potential use of p-nitro azobenzene diaza-18-crown-6 as naked-eye sensors, notably for Cr3+ that brings acute toxic to aquatic life.

Poly(Ionic Liquid) Based Chemosensors for Detection of Basic Amino Acids in Aqueous Medium.

Naked-eye detection of amino acids (AA) in water is of great significance in the field of bioanalytical applications. Herein, polymerized ionic liquids (PILs) with controlled chain length structures were synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization and post-quaternization approach. The AA recognition performance of PILs with different alkyl chain lengths and molecular weights was evaluated by naked-eye color change and ultraviolet-visible (UV-vis) spectral studies. These PILs were successfully used for highly sensitive and selective detection of Arg, Lys, and His in water. The recognition performance was improved effectively with increased molecular weight of PILs. The biosensitivity of the PILs in water was strongly dependent on their aggregation effect and polarization effect. Highly sensitive and selective detection of AA was successfully accomplished by introducing positively charged pyridinium moieties and controlled RAFT radical polymerization.