Anions In Aqueous Media Research Articles

‘Naked-eye’ detection of biologically important anions in aqueous media by colorimetric receptor and its real life applications

A colorimetric receptor R 2-[(2-Hydroxy-naphthalen-1-ylmethylene)-hydrazonomethyl]-quinolin-8-ol has been designed and synthesized with good yield and characterized by the standard spectroscopic techniques such as FT-IR, UV–Visible, 1H NMR, 13C NMR and ESI-MS. The receptor R showed naked-eye detection and spectral change in the presence of F−, AcO− and H2PO4− over other anions. Interestingly, receptor R displaying high selective recognition towards F−, AcO− ion with a drastic color change from pale yellow to red in dry DMSO solvent and orange in mixed solvent DMSO/H2O (9:1, v/v). The behavior of receptor R towards F−, AcO− ion was investigated using UV–Vis and 1H NMR experiment. The detailed 1H NMR experiment result revealed that the receptor R is forming the hydrogen bonding between imine nitrogen and phenolic OH proton towards anions. The receptor R is able to detect sodium salts of flouride (NaF) and acetate (NaAcO) in aqueous medium and it exhibited dramatic color change from pale yellow to red. The receptor R demonstrated itself to be useful for real life application by detecting flouride and acetate ion in sea-water and commercially available product such as toothpaste, mouthwash and vinegar solution.

Highly selective colorimetric detection of cyanide anions in aqueous media by triphenylamine and phenanthro(9,10-d)imidazole based probes.

Two novel fluorescent probes based on triphenylamine (TPC) and phenanthro(9,10-d-imidazole) (PITP) have been synthesized and studied as cyanide selective indicators in aqueous media. Complete colour bleaching was observed due to the nucleophilic addition of cyanide to the 2-vinylmalononitrile of TPC, which results in the disruption of the extended conjugation and turns off the intramolecular charge transfer (ICT) process. Furthermore, a visible color change was observed with a large Stokes shift (108 nm) upon the addition of cyanide anions to PITP, due to the formation of hydrogen bonding between the CN- anion and -NH of PITP, which increased the electron density on the donor moiety and induced strong ICT.

Curcumin based chemosensor for selective detection of fluoride and cyanide anions in aqueous media.

The conjugate N,N-dimethyl curcumin analogue fluorophore dye 1 has been synthesized and its performance as a sensor was demonstrated. As a fluoride and cyanide sensor it enabled visual detection, and showed changes in UV-vis and fluorescence spectra in the presence of fluoride and cyanide ions in aqueous medium. The Job's plot indicated that the formation of a complex between dye-1 fluoride ions has a 1 : 1 stoichiometric ratio.

Di- and Triphosphate Recognition and Sensing with Mono- and Dinuclear Fluorescent Zinc(II) Complexes: Clues for the Design of Selective Chemosensors for Anions in Aqueous Media.

The synthesis of a new ligand (L1) containing two 1,4,7-triazacyclononane ([9]aneN3 ) moieties linked by a 4,5-dimethylenacridine unit is reported. The binding and fluorescence sensing properties toward Cu2+ , Zn2+ , Cd2+ , and Pb2+ of L1 and receptor L2, composed of two [9]aneN3 macrocycles bridged by a 6,6''-dimethylen-2,2':6',2''-terpyridine unit, have been studied by coupling potentiometric, UV/Vis absorption, and emission measurements in aqueous media. Both receptors can selectively detect Zn2+ thanks to fluorescence emission enhancement upon metal binding. The analysis of the binding and sensing properties of the Zn2+ complexes toward inorganic anions revealed that the dinuclear Zn2+ complex of L1 selectively binds and senses the triphosphate anion (TP), whereas the mononuclear Zn2+ complex of L2 displays selective recognition of diphosphate (DP). Binding of TP or DP induces emission quenching of the Zn2+ complexes with L1 and L2, respectively. These results are exploited to discuss the role played by pH, number of coordinated metal cations, and binding ability of the bridging units in metal and/or anion coordination and sensing.

Naked-eye detection of cyanide ions in aqueous media based on an azo-azomethine chemosensor

The optical and colorimetric properties of a new chemosensor 4-((2,4-dichlorophenyl)diazenyl)-2-(3-hydroxypropylimino)methyl)phenol (L) for cyanide ions were investigated by the naked-eye detection and UV–vis spectroscopy. This receptor reveals visual changes toward CN− anions in aqueous media. No significant color changes were observed upon the addition of any other anions. The cyanide recognition properties of the receptor through proton-transfer were monitored by UV–vis titration and 1H NMR spectroscopy. The binding constant (Ka) and stoichiometry of the formed host–guest complex were calculated by the Benesi–Hildebrand (B–H) plot and Job's plot method, respectively. The detection limit of the probe towards CN− was 1.03 × 10−6 mol L−1, which is lower than the maximum value of cyanide (1.9 × 10−6 mol L−1) permitted by the World Health Organization in drinking water. Thus, this chemosensor was sensitive enough to detect cyanide in aqueous solutions. 1H NMR experiments were conducted to investigate the nature of interaction between the receptor and CN− anions. Notably, the designed sensor can be applied for the rapid detection of cyanide anions in the basic pH range and also under physiological conditions, for practical purposes for a long duration. The sensing behavior of the receptor was further emphasized by computational studies. Quantum-chemical calculations and molecular studies via Density Functional Theory (DFT) were carried out to supplement the experimental results.

A pyrylium–coumarin dyad as a colorimetric receptor for ratiometric detection of cyanide anions by two absorption bands in the visible region

A pyrylium–coumarin dyad behaves as a colorimetric receptor for ratiometric detection of cyanide anions in aqueous media by two absorption bands in the visible wavelength region.

A colorimetric and ratiometric fluorescent probe for the selective detection of cyanide anions in aqueous media and living cells

Based on the internal charge transfer (ICT) mechanism, a novel colorimetric and ratiometric fluorescent probe was developed for highly selective and sensitive detection of cyanide ion in aqueous media.

Novel chemosensor for multiple target anions: The detection of F− and CN− ion via different approach

Abstract A novel chemosensor based on azo linked Schiff base (receptor 1 ) was synthesized by simple condensation method. The sensor studies of receptor 1 disclose the selectivity toward fluoride and cyanide ion with a color change among the other common anions in aqueous medium. The binding affinity of receptor 1 was also enlightened by 1 H NMR titration and DFT calculation.

Pyrene and imidazole functionalized luminescent bimetallic Ru(II) terpyridine complexes as efficient optical chemosensors for cyanide in aqueous, organic and solid media.

We report in this work the anion recognition and sensing aspect of a new family of bimetallic Ru(ii) complexes derived from a symmetrical bridging 5,11-bis(4-([2,2':6',2''-terpyridine]-4'-yl)phenyl)-4,12-dihydropyreno[4,5-d:9,10-d']diimidazole (tpy-H2PhImzPy-tpy) terpyridine ligand in solution as well as in the solid sate through different channels such as absorption, steady state and time-resolved emission, and (1)H NMR spectroscopic techniques. Interestingly, the complexes exhibit luminescence in the red region with moderately long lifetimes compared with the related terpyridine complexes of Ru(ii). In DMSO, complexes 1 and 2 act as sensors for F(-) and to a lesser extent for AcO(-), CN(-) and H2PO4(-), whereas 3 acts as a sensor for F(-), AcO(-), CN(-) and to some extent for H2PO4(-). In contrast to DMSO, all the complexes exhibit very high selectivity towards cyanide ions in the presence of an excess of other anions in aqueous medium. The complexes display visual detection of cyanide with the detection limit lying in the range of 1.01 × 10(-7) to 9.79 × 10(-8) M. Equilibrium constants for the interaction of the complexes with the anions were evaluated from absorption and emission titration profiles and were found to lie in six orders of magnitude. It is observed that the excited-state lifetimes of the complexes were modulated to a significant extent by the selected anions in all the three media proving the utility of such complexes to act as lifetime-based sensors for anions. The fact that all the complexes can selectively sense cyanide in the presence of other anions with their detection limits lying in the range of 10(-7) M-10(-8) M in aqueous solution is particularly important for their practical applicability. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) studies were performed to understand the nature of the ground and excited states of the complexes with detailed assignments of the orbitals involved in absorption transitions. In particular, the red-shifts of the absorption and emission bands in the presence of selective anions have been well reproduced by computations.

Colorimetric detection of anions in aqueous media using N-monosubstituted diaminomaleonitrile-based azo-azomethine receptors: Real-life applications

New N-monosubstituted diaminomaleonitrile-based azo-azomethine dyes have been synthesized in order to develop colorimetric sensors for detection of biologically important anions in aqueous media. Importantly, the reported sensor decorated with strong electron-withdrawing group can detect inorganic fluoride in water even at 0.037ppm level, which is lower than WHO permissible level (below 1ppm). Successfully, the prepared dyes were used for qualitative and quantitative detection of inorganic fluoride in toothpaste and mouthwash. The anion recognition mechanism was also investigated by detailed UV–Vis and 1H NMR experiments. The detailed 1H NMR experiments corroborated that anion recognition is based on the deprotonation phenomenon.

ChemInform Abstract: Recent Developments in Anion Induced Capsular Self‐Assemblies

AbstractReview: 102 refs.

Rapid, selective, and sensitive fluorometric detection of cyanide anions in aqueous media by cyanine dyes with indolium-coumarin linkages.

Cyanine dyes with indolium-coumarin linkages exhibit selective fluorescence enhancement for cyanide anions (CN(-)) via the nucleophilic interaction of CN(-) with their indolium carbon atoms. This facilitates rapid (detection time: 1 min) and sensitive (detection limit: 0.4 μM) sensing of CN(-) in aqueous media.

The ferrocene-pyrylium dyad as a selective colorimetric chemodosimeter for the toxic cyanide and hydrogen sulfide anions in water

The ferrocene-pyrylium dyad behaves as a selective redox and colorimetric chemodosimeter for CN(-) and HS(-) anions, exhibiting a clear perturbation in the redox potential of the ferrocene unit and in the absorption band, in the presence of these anions.

A rhodamine B-based “turn-on” fluorescent sensor for detecting Cu2+ and sulfur anions in aqueous media

A novel selective fluorescent chemosensor L based on rhodamine B derivative has been designed and synthesized to optically detect Cu2+ and S2− in aqueous buffer solution. The fluorescence of L was excited by Cu2+ with a 1 : 1 binding ratio, and could be used as a “turn-on” type sensor. Otherwise, the emission band would undergo a slight red-shift. Once binding with Cu2+, the copper complex can exhibit high selectivity for S2−. Upon addition of Cu2+, the color of the chemosensor L changes from colorless to pink. Additionally, the resulting pink solution changes to colorless immediately upon the addition of S2−. However, no phenomenon change could be observed in the presence of other anions. Conclusively, the color changes suggest that sensor L could serve as a “naked-eye” sensor for Cu2+ and S2−.

Cathodic corrosion. I. Mechanism of corrosion via formation of metal anions in aqueous medium

In this paper we describe an unusual electrochemical phenomenon, namely, cathodic corrosion of platinum. We show that all existing models of cathodic corrosion are inconsistent with our experimental observations. Therefore, we present a new model of cathodic corrosion, which is based on the assumption that metal anions are formed at the electrode surface during the corrosion process. These anionic species function as precursors for the formation of the final product of cathodic corrosion, i.e., metal nanoparticles.

Facile, divergent route to bis-Zn(II)dipicolylamine type chemosensors for pyrophosphate

A new, two-step synthesis has been developed for a series of bis-DPA-type ligands whose dinuclear Zn(II) complexes function as fluorescent anion sensors. The Zn(II) complexes exhibit good selectivity for PPi over other anions in aqueous medium (pH 7.5) and may be used to monitor the extent of enzyme-catalysed reactions, in which PPi is produced or consumed.

Anion Sensing in Aqueous Media by Photo‐active Transition‐Metal Bipyridyl Rotaxanes

A chloride anion templation methodology is utilized in the construction of novel transition-metal rhenium(I) and ruthenium(II) bipyridyl appended [2]rotaxanes. (1)H NMR spectroscopic titrations reveal the ability of the rotaxanes to selectively bind chloride over the more basic oxoanions, with the ruthenium(II) bipyridyl appended rotaxane strongly binding chloride in 30% water. Photophysical investigations demonstrate the ability of the rotaxanes to sense anions in aqueous media, with chloride being selectively complexed, in general agreement with NMR spectroscopy determined anion binding data.

Rapid simultaneous analysis of oxyhalides and inorganic anions in aqueous media by ion exchange chromatography with indirect UV detection

Simultaneous analyses of oxyhalides (BrO3-,ClO3-) and inorganic anions (Cl-,Br-,NO3-andSO42-) have been achieved on metrosep anion dual1 Metrohm as polymer column (150 × 3 mm D.I.) with ortho-phtalic acid as a visualization agent and as ion developer constituent of the mobile phase. The separations have occured without interferences and any base line perturbation.Best separations have also occured between (Cl-/ClO3-) and (Br-/BrO3-) with good a resolution. Detections limits (S/N = 3) of BrO3-,ClO3-andNO3- were 2 and 5 ppm for inorganic anions Cl−, Br− and SO42-. The method had a good linearity (r2 > 0.995) and high precision (relative standard deviation) <4%. The main reason for the detector choice was that UV detectors are widespread in educational and low level equipment laboratories. Indirect photometric detection is an attractive and inexpensive approach and the system is versatile.

A chemodosimetric gelation system showing fluorescence and sol-to-gel transition for fluoride anions in aqueous media

We developed a chemodosimetric gelation system which turns into a fluorescent gel in the presence of fluoride anions in aqueous media. The selective cleavage of a silyl ether protecting group on the gelator by a fluoride anion gives rise to an optical change (fluorescence turn-on) and a sol-to-gel transition in aqueous media.

Core/Shell Cu@Ag Nanoparticle: A Versatile Platform for Colorimetric Visualization of Inorganic Anions

Recognition and sensing of anions in aqueous media have been of considerable interest while remaining a challenging task up to date. In this document, we wish to present a simple yet sensitive method to detect inorganic anions by colorimetry based on the citrate-stabilized core/shell Cu@Ag nanoparticle (NP). It was found that the NP could discriminate some specific anions (Cl(-), Br(-), I(-), S(2-), and SCN(-)) from a wide range of environmentally dominant anions (F(-), SO(4)(2-), H(2)PO(4)(-), CO(3)(2-), NO(3)(-), etc), identified by the change in the color of the buffered NP solution or the surface plasmon resonance (SPR) absorbance band in the UV-vis spectrum. Among the recognized anions, four types of variation in the SPR absorption band were revealed. It was strongly enhanced for Cl(-) and Br(-) and was strongly damped for S(2-). For I(-), it first was slightly enhanced at lower concentrations and then gradually was damped at higher concentrations. For SCN(-), it first was slightly damped at lower concentrations and then was strongly enhanced at higher concentrations. In response to the optical change, the color of the NP solution turned from brown to bright yellow for Cl(-) (1 mM), Br(-) (10 μM), and SCN(-) (50 μM) to brownish orange for I(-) (10 μM) and to reddish orange for S(2-) (50 μM). The reason for these phenomena was postulated by the evidence of transmission electron microscope (TEM) images, X-ray photoelectron spectroscopy (XPS), and zeta potentials. In view of the importance of anions in the environment and for human health, the Cu@Ag NP colorimetric platform may have some applications, such as discriminating household table salt (NaCl) from industrial salt (NaNO(2)), testing the quality and extent of a variety of waters, and so forth.