Epoxy-based oligomeric probe bearing naphthalene units for selective turn-OFF fluorescent sensing of fluoride anion

A simple epoxy-based oligomer 1 bearing naphthalene unit at the chain-ends is reported to be highly selective ON–OFF type fluorescent probe for fluoride anion. The titled oligomer displayed fluorescence quenching upon addition of F^?, resulting in selective detection of fluoride anion over other anions, such as AcO^?, Cl^?, Br^?, I^?, HSO₄^?, NO₃^? and H₂PO₄^? in CH₃CN. Fluorescence experiments suggest the significant influence of the oligomer chain on the sensitivity and selectivity of 1 towards fluoride anion.     

An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO₃⁻) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO₃⁻ based on the Michael addition reaction with a limit of detection 5.3 × 10⁻⁸ M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application.     

用于活体和细胞内SO2衍生物检测的线粒体靶向双光子磷光铱(Ⅲ)配合物

暴露于高剂量的二氧化硫（SO₂）及其衍生物（SO₃^2-和HSO₃^-）会导致血管疾病甚至肺癌发生。双光子磷光成像显微术（TPPIM）和双光子磷光寿命成像显微术（TPPLIM）具有良好的时空分辨能力、抗光漂白、抗自体荧光以及较强组织穿透性等优点,可以实现SO₂衍生物在生物样品中实时检测。得益于铱配合物的长磷光寿命（~110 ns）和线粒体靶向特性,本文报道了首例基于TPPLIM技术的SO₂衍生物检测探针Ir-EA。Ir-EA对水溶液中的亚硫酸氢盐表现出高特异性和灵敏性的识别能力（69倍磷光增强,10倍亚硫酸氢盐）和较低的检测限（65 nmol·L^-1）。更为重要的是,Ir-EA对活细胞和斑马鱼的线粒体中SO₂衍生物表现出良好的成像效果。     

A dipodal thiourea-ionic liquid conjugate system for selective ratiometric detection of HSO4− ion in purely aqueous medium: Application to real sample analysis

A benzimidazolium based thiourea conjugate (IL) receptor has been designed, synthesized and characterized spectroscopically. The prepared receptor (IL) shows the sensitive and selective ratiometric sensing for HSO₄^? over the other anions as evident by UV–visible absorption and fluorescence spectroscopy. With the addition of HSO₄^? ion, the parent absorption band of IL in UV–visible absorption at 311 nm was shifted to 261 nm having an isosbestic point at 294 nm, which clearly indicates an interaction between HSO₄^? ion and the IL. Further, upon excitation at 310 nm, the fluorescence emission of IL at 455 nm was observed. Furthermore, the gradual addition of HSO₄^? ion results in a drastic decrease in emission at 455 nm and simultaneous appearance of a new emission band at 379 nm with isosbestic point at 430 nm was observed. The binding mechanism of HSO₄^? with IL was also explored with ¹H NMR titration, mass spectrometry and DFT calculations. These studies revealed the involvement of hydrogen bonding with –NH (thiourea) and –CH (benzimidazolium) functionalities towards the recognition of HSO₄^? ion. The association constant (K_a) and lowest detection limits for HSO₄^? were determined to be 5.437 × 10⁴ M^?1 and 5.0 nM, respectively. The real sample analysis by synthesized sensor probe for HSO₄^? was also performed which shows the practical applicability of the developed sensor system.     

Indole-based distinctive chemosensors for ‘naked-eye’ detection of CN and HSO4−, associated with hydrogen-bonded complex and their DFT study

Colorimetric detection of anions (HSO₄^? and CN^?) was achieved via analyte triggered colour changing of the dipodal and tripodal sensors in CH₃CN–H₂O (1:1). The sensors exhibited very sharp visual colour changes and fluorescence quenching–enhancing effect upon addition of the HSO₄^? and CN^?. The large downfield shift of the NH proton signals in ¹H-NMR complexation studies and quantum chemical DFT calculations proved the formation of hydrogen-bonded complexes where no proton transfer mechanism was found.     

A two-photon fluorescent turn-on probe for imaging of SO2 derivatives in living cells and tissues

SO₂ and its derivatives (bisulfite/sulfite) play crucial roles in several physiological processes. Therefore, development of reliable analytical methods for monitoring SO₂ and its derivatives in biological systems is very significant. In this paper, a FRET-based two-photon fluorescent turn-on probe, A-HCy, was proposed for specific detection of SO₂ derivatives through the bisulfite/sulfite-promoted Michael addition reaction. In this FRET system, an acedan (2-acetyl-6-dialkylaminonaphthalene) moiety was selected as a two-photon donor and a hemicyanine derivative served as both the quencher and the recognition unit for bisulfite/sulfite. A-HCy exhibited excellent selectivity and rapid response to HSO₃⁻ with a detection limit of 0.24 μM. More importantly, probe A-HCy was first successfully applied in two-photon fluorescence imaging of biological SO₂ derivatives in living cells and tissues, suggesting its great potential for practical application in biological systems.     

Recent development in fluorescent probes based on attacking of double bond and masking of functional group

The works on the procedure of fluorescent sensors for the detection of biological analytes are extremely momentous.Among diverse analytical approaches,fluorescence is the most eye-catching due to its high sensitivity,selectivity,rapidity,robustness,ease of measurement and non-destructive approaches.Herein,we show different fluorescent probes synthesized for estimation and detection of biological analytes(H₂S,SO₃^2-/HSO₃^-,H₂O_2<...     

A Novel Fluorescence Probe for the Reversible Detection of Bisulfite and Hydrogen Peroxide Pair in Vitro and in Vivo

The detection of changes in the reactive oxygen species (ROS)/reactive sulfur species (RSS) couple is important for studying the cellular redox state. Herein, we developed a 1,8-naphthalimide-based fluorescence probe ( NI ) for the reversible detection of bisulfite (HSO₃⁻) and hydrogen peroxide (H₂O₂) in vitro and in vivo. NI has been designed with a reactive ethylene unit which specifically reacts with HSO₃⁻ by a Michael addition reaction mechanism, resulting in the quenching of yellow fluorescence at 580 nm and the appearing of green fluorescence at 510 nm upon excitation at 500 nm and 430 nm, respectively. The addition product ( NI−HSO₃ ) could be specifically oxidized to form the original C=C bond of NI , recovering the fluorescence emission and color. The detection limits of NI for HSO₃⁻ and NI−HSO₃ for H₂O₂ were calculated to be 2.05 μM and 4.23 μM, respectively. The reversible fluorescence response of NI towards HSO₃⁻/H₂O₂ couple can be repeated for at least five times. NI is reliable at a broad pH range (pH 3.0–11.5) and features outstanding selectivity, which enabled its practical applications in biological and food samples. Monitoring the reversible and dynamic inter-conversion between HSO₃⁻ and H₂O₂ in vitro and in vivo has been verified by fluorescence imaging in live HeLa cells, adult zebrafish and nude mice. Moreover, NI has been successfully applied to detect of HSO₃⁻ levels in food samples.     

A coumarin-based fluorescent and colorimetric chemosensor for rapid detection of fluoride ion

A novel coumarin-based compound 1 featuring thiosemicarbazone as binding unit, was reported as a colorimetric and fluorescent probe for the detection of fluoride anion. The addition of F^? to a solution of probe 1 in tetrahydrofuran resulted in evident naked-eye color change from green-yellow to orange-red under daylight and obvious fluorescence quenching within 3 s. And the detection limit toward F^? was calculated to be as low as 2.16 × 10^?7 mol/L. ¹H NMR titrations proved that the interaction between 1 and fluoride ion: hydrogen bond at low fluoride ion concentration, deprotonation at high fluoride ion concentration. Besides, it exhibited highly sensitivity and selectivity for F^? over other examined ions (Cl^?, Br^?, I^?, AcO^?, NO₃^?, HSO₄^?, H₂PO₄^?) in tetrahydrofuran solution.     

A new benzimidazolium incorporated chemodosimeter affording dual chromogenic and fluorescence switch-on signaling for the selective targeting of cyanide

We have designed and synthesized a new chemodosimeter, Benzolin-A, which selectively responds to toxic cyanide by dual colorimetric and fluorescence turn-on responses in buffered aqueous DMSO. In the presence of cyanide, we observe absorbance red shift of 108 nm (color changing from colorless to yellow) and fivefold fluorescence enhancement. The ¹H NMR studies confirm the nucleophilic addition mechanism, and consistent with the experimental findings, the computational work predicts the feasibility of photoelectron transfer or energy transfer process in the native probe, as well as enhanced internal charge transfer in the Benzolin-A-cyanide adduct. Noteworthily, several background anions, such as F^?, Cl^?, AcO^?, SCN^?, HSO₄ ^?, NO₃ ^?, Br^?, I^? and H₂PO₄ ^? exhibit none or insignificant optical perturbations.     

A highly selective chemosensor derived from benzamide hydrazones for the detection of cyanide ion in organic and organic-aqueous media: design,synthesis, sensing and computational studies

ABSTRACT

A new, highly sensitive and selective chemosensing method has been developed for the detection of cyanide ion using benzamide hydrazone receptors (R1-R4). The sensing ability of these compounds towards CN^? in the presence of Br ^?, HSO₄ ^?, Cl^?, OH^?, I^?, F^?, AcO^?, NO₂ ^? and NO₃ ^? in DMF and DMF-Aqueous mixture (DMF:H₂O, 9:1 v/v) was investigated. The binding characteristics of the probe with cyanide ions carried out by ¹ H NMR titrations indicated the deprotonation of N-H group through H-bond interactions between benzamide hydrazones and cyanide ions; it has been theoretically supported by DFT. The binding constant (Ka) and stoichiometry of the host–guest complex formed was calculated by the Benesi–Hildebrand (B–H) plot, and strong interaction of the probe with CN^- ions forming a 1:2 binding stoichiometry has been noted in this study. In a DMF and aqueous medium for CN^? ion, the lower limit of detection (LOD in ppm) is compared to the limit of quantification (LOQ in ppm), which is quite better in terms of sensitivity.     

A ratiometric fluorescent probe for zinc ions based on the quinoline fluorophore

A ratiometric fluorescent zinc probe 1 of carboxamidoquinoline with a carboxylic acid group was designed and synthesised. Probe 1 exhibits high selectivity for sensing Zn²⁺; about a 13-fold increase in fluorescence emission intensity and an 82?nm red-shift of fluorescence emission are observed upon binding Zn²⁺ in EtOH/H₂O (1?:?1, V/V) solution. The ratiometric fluorescence response is attributed to the 1?:?1 complex formation between probe 1 and Zn²⁺ which has been utilised as the basis for the selective detection of Zn²⁺. The analytical performance characteristics of the proposed Zn²⁺-sensitive probe were investigated. The linear response range covers a concentration range of Zn²⁺ from 2.0?×?10^?6 to 5.0?×?10^?5?mol?L^?1 and the detection limit is 2.7?×?10^?7?mol?L^?1. The determination of Zn²⁺ in both tap and river water samples shows satisfactory results.     

Mono Halogen Substituted Calix[4]pyrroles: Fine-tuning the Anion Binding Properties of Calix[4]pyrrole

Abstract

Single halogen atom (i. e. I, Br, Cl and F) substituted calix[4]pyrroles, compounds 2, 3, 4 and 5, were synthesized. Studies of these systems reveal that replacement of a single β-pyrrolic hydrogen atom can increase the anion binding ability of calix[4]pyrroles for a variety of anions (e. g. Cl^?, Br^?, H₂PO₄ ^? and HSO^? ₄) relative to normal non-halogen substituted calix[4]pyrrole 1. In the case of chloride anion, the expected relative affinity sequence of 5 > 4 > 3 > 2 was observed. This was not found to be true for Br^?, H²PO^? ₄, and HSO^? ₄. Here, the chlorine substituted calix[4]pyrrole 4 was found to display a slightly higher affinity in the case of each anion than the fluorine-bearing derivative 5. This was rationalized in terms of intermolecular NH … F hydrogen bonding interactions being present in CD₂Cl₂ solutions of 5. Support for this latter conclusion came from concentration and temperature-dependent NMR spectroscopic studies.

A matched set of mono halogen substituted calix[4]pyrroles was used to study in detail, the extent to which halogen substituents may be used to fine-tune the anion binding properties of calix[4]pyrroles.     

Mono-, di-, and trinuclear phosphonate oxygen-bridged copper(II) complexes: syntheses,structures, and properties

Reactions of copper salts, zoledronic acid, and 2,2′-bipyridine/1,10-phenanthroline in aqueous ethanolic solutions afforded four phosphonate oxygen-bridged copper complexes, Cu(bipy)(H₄zdn)(HSO₄) (1), [Cu₂(bipy)₂(H₂zdn)(H₂O)(Cl)]·4H₂O (2), [Cu₂(phen)₂(H₂zdn)(H₂O)(Cl)]·2.5H₂O (3), and [Cu₃(bipy)₃(H₄zdn)(H₂zdn)(SO₄)]·5H₂O (4) (H₅zdn = zoledronic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline). The copper centers of 1–4 have square pyramidal coordination geometries. The Cu(II) ions are coordinated to bipy/phen, zoledronate, and HSO₄^?/Cl^? forming mononuclear units for 1, dinuclear for 2 and 3, and trinuclear for 4. These building units are further extended into 3-D supramolecular networks via multiple hydrogen bond interactions. Temperature-dependent magnetic properties of 2 and 4 suggest weak antiferromagnetic coupling (J = ?4.53(8) cm^?1 for 2, J = ?1.69(4) cm^?1 for 4). The antitumor activity of 2 was evaluated against the human lung cancer cell line and indicates effective time- and dose-dependent cytotoxic effects.     

Polymeric ISE for Hydrogen Sulfite Based on Bis‐Urea Calix[4]diquinones as Neutral Lipophilic Ionophores

A new PVC membrane electrode for HSO₃^? anion based on bis‐urea calix[4]diquinones I–VI as neutral ionophores is prepared. Of the various membranes prepared, the membrane based on calix[4]diquinone III exhibits a linear stable response over a wide concentration range (6.0×10^?5?1.0×10^?2) with a slope of ?51.5 mV/decade and a detection limit of 2.2×10^?6 M. With the exception of HSO₃^? anion, the remainder of the anions responds based on their hydrophobicity. The membrane revealed improved selectivity coefficients for HSO₃^? over a wide variety of other anions, and the comparable selectivity for the HSO₃^?selective membranes is iodide anion.     

Oxidative Deprotection Of Trimethylsilyl and Tetrahydropyranyl Ethers and Ethylene Acetals With Benzyltriphenylphosphonium Peroxomonosulfate in the Presence of Bismuth Chloride Under Non-Aqueous Conditions

Abstract

Benzyltriphenylphosphonium peroxomonosulfate (BnPh₃P⁺HSO₅ ^?) (1) is used as a new reagent for oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers and ethylene acetals to afford carbonyl compounds in refluxing acetonitrile in the presence of bismuth chloride.     

Reaction‐Based Colorimetric and Ratiometric Fluorescence Sensor for Detection of Cyanide in Aqueous Media

A stilbene‐based compound ( 1 ) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F^?, Cl^?, Br^?, I^?, ClO₄^?, H₂PO₄^?, HSO₄^?, NO₃^?, and CH₃CO₂^?. A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron‐deficient cyanoacrylate group of 1 . The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge‐transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations.     

A 1-Hydroxy-2,4-Diformylnaphthalene-Based Fluorescent Probe and Its Detection of Sulfites/Bisulfite

A novel 1-hydroxy-2,4-diformylnaphthalene-based fluorescent probe L was synthesized by a Knoevenagel reaction and exhibited excellent sensitivity and selectivity towards sulfite ions (SO₃²⁻) and bisulfite ions (HSO₃⁻). The detection limits of the probe L were 0.24 μM using UV-Vis spectroscopy and 9.93 nM using fluorescence spectroscopy, respectively. Furthermore, the fluorescent probe L could be utilized for detection in real water samples with satisfactory recoveries in the range 99.20%~104.30% in lake water and 100.00%~104.80% in tap water by UV-Vis absorption spectrometry, and in the range 100.50%~108.60% in lake water and 102.70%~103.80% in tap water by fluorescence spectrophotometry.     

Highly selective probe of a copper(II) complex based on a coumarin derivative for hydrogen sulfide detection

Abstract

A fluorescent probe 1 containing copper(II) had been designed and synthesized based on a coumarin derivative. The molecular structure of probe 1 was characterized by ¹H NMR, HRMS, IR, and elemental analysis. The interactions of 1 with biologically important anions and amino acid were determined by UV–Vis, fluorescence, and HRMS titration experiments. Results indicated that probe 1 showed the highest binding ability for HS^? among studied anions (AcO^?, H₂PO₄^?, F^?, Cl^?, Br^?, and I^?) and cysteine in pure dimethyl sulfoxide (DMSO) and HEPES buffer solution. As we expected, the response of UV–Vis spectra in aqueous solution was stronger than that of pure DMSO solvent. In addition, the binding ability for HS^? was not hindered by the existence of other anions. HRMS titration experiment showed that the interacted mechanism was that the copper(II) ion in 1 was captured by HS^? and then free ligand released. Furthermore, the detection limit of probe 1 with HS^? was carried out through UV–Vis titration showing 1 to be highly sensitive for HS^?.     

The Use of the CS2N− 3/HSO− 3/O2 Reaction for the Analytical Determination of Dissolved Oxygen

Abstract

A new analytical Spectrophotometric method has been developed for the determination of dissolved O₂ in the range 4.6 × 10^?6?4.1 × 10^?5M, based on the CS₂N^? ₃/HSO^? ₃/O₂ reaction. In one single experiment 2.3 × 10^?5 M of oxygen can be determined with an uncertainty of ± 7 × 10^?7M for a confidence level of 95%.