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[Display omitted] • A dual-response florescent probe based on phenanthroimidazole for N 2 H 4 and HSO 3 – detection was developed. • EPC for N 2 H 4 and HSO 3 – detection displayed low detection limits of 0.182 µM and 0.093 µM, respectively. • EPC based test paper can be used as a simple device for quantitative determining of N 2 H 4 in environmental samples. • Probe EPC was feasible for the detection of HSO 3 – in food samples. Hydrazine (N 2 H 4) and bisulfite (HSO 3 –) detection methods are urgently needed due to its harmful to the human health and environment safety. Herein, we reported a dual-response fluorescence probe EPC , which is capable of sequential detection of N 2 H 4 and HSO 3 – by two different fluorescence signals. The probe EPC itself showed yellow florescence. In presence of N 2 H 4 , probe EPC exhibited an obviously fluorescence change (from yellow to green). However, a new addition product came into being after probe EPC mixed with HSO 3 –, followed with weak yellow emission. More important, probe EPC exhibited excellent fluorescence response properties for N 2 H 4 and HSO 3 –, such as high sensitivity (0.182 µM for N 2 H 4 , 0.093 µM for HSO 3 –), rapid response (55 s for N 2 H 4 , 45 s for HSO 3 –), excellent selectivity and anti-interference performance. The sensing mechanisms for N 2 H 4 and HSO 3 – were proved by 1H NMR and MS spectra. Practical applications were studied. EPC based test paper can be utilized for quantitative detecting N 2 H 4 in actual water samples. And, probe EPC has been successfully applied to recognize N 2 H 4 contaminant in soil samples. Moreover, EPC has great potential to be used to detect HSO 3 – in real food samples. [ABSTRACT FROM AUTHOR]

Biomercaptan, bisulfite (HSO 3 −) and hydrogen sulfide (H 2 S) are involved in many physiological and pathological processes in the human body. Therefore, it is of great significance to develop a fluorescent probe that can simultaneously detect and distinguish biological mercaptans from HSO 3 − and S2−. The probe CDI-1 was synthesized by combining coumarin with hemicyanine. The maximum absorption wavelength of the probe is at 609 nm. After adding Cys/Hcy and GSH, the probe shows varying degrees of blue shift, which can be used to distinguish Cys/Hcy and GSH. After it reacts with Cys/Hcy, the fluorescence intensity of the solution increases about twice, while it increases three times after it reacts with GSH. This phenomenon can also be used to distinguish Cys/Hcy from GSH. The probe CDI-1 can react with Cys completely within 30 min, with Hcy or GSH completely within 80 min, and with HSO 3 − and S2− quickly within 20 min. The study on the effect of pH on the fluorescence performance of CDI-1 shows that the probe is suitable for detecting biological mercaptan or HSO 3 −, S2− in weak acid to weak alkali environments. The selectivity study showed that the probe CDI-1 had high specificity for biological mercaptan, HSO 3 − and S2−. This provides a new and simple method for simultaneous detection of biological mercaptan, HSO 3 − and S2− ions. UV–Vis absorption spectra of CDI-1 interaction with small molecules. Solvent: EtOH/PBS (v/v, 5/5, pH = 7.4); CDI-1: 20 μM; Analytes: Cys, Hcy, GSH, Thr, Ile, His, Glu, Ala, Gly, Ser, Met, Phe, Pro, Leu, Asn, Lys, Val, S2−, HSO 3 − (200 μM)CDI-1 has specificity for the detection of HSO 3 −, S2− and biothiols. [Display omitted] • The probe CDI-1 had high specificity for biological mercaptan, HSO 3 − and S2-. • The probe CDI-1 can simultaneously detect biothiols and HSO 3 − and S2-. • CDI-1 has good stability in weak acid and weak base environments. [ABSTRACT FROM AUTHOR]

The emission of venenous sulfur dioxide (SO 2) and its derivatives from industrial applications such as coking, transportation and food processing has caused great concern about public health and environmental quality. Probes that enable sensitivity and specificity to detect SO 2 derivatives play a crucial role in its regulations and finally mitigating its environmental and health impacts, but fluorescent probes that can accurately, rapidly and on-site detect SO 2 derivatives in foodstuffs and environmental systems rarely reported. Herein, a near-infrared (NIR) fluorescent probe (ZTX) for the ratiometric response of bisulfite (HSO 3 −) was designed and synthesized by regulating the structure of high-performance HSO 3 − fluorescent probe SL previously reported by us based on structural analyses, theoretical calculations and related literature reports. The Michael addition reaction between the electronic-deficient C=C bond and HSO 3 − destroys ZTX 's π-conjugation system and blocks its intramolecular charge transfer (ICT) process, resulting in a significant fading of the fuchsia solution and the bluish-purple fluorescence turned light blue fluorescence. Fluorescent imaging of HSO 3 − in live animals utilizing ZTX has been demonstrated. The quantitative analysis of HSO 3 − in food samples using ZTX via a smartphone has been also successfully implemented. Simultaneously, the ZTX -based test strips were utilized to quantificationally determine HSO 3 − in environmental water samples by a smartphone. Consequently, probe ZTX could provide a new method to understand the physiopathological roles of HSO 3 −, evaluate food safety and monitor environment, and is promising for broad applications. [Display omitted] • The fluorescence probe ZTX features NIR-emitting (849 nm), large Stokes shift (326 nm) and high biocompatibility. • The quantitative determination of HSO 3 − in environmental water and actual food sampleswere realized using ZTX combined with a smartphone. • Applications of ZTX in fluorescence imaging of HSO 3 − in vivo in mouse model are successfully demonstrated. [ABSTRACT FROM AUTHOR]

Fluorescence probes bearing malononitrile derivatives as electron withdrawing group have attracted the interests of many researchers during the past decades. Even for the similar fluorophore, the sensing mechanism and pathway could be much different and hard to predict. Thus, we designed a fluorescence probe consisting 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)malononitrile as the electron withdrawing group and thienocoumarin as fluorophore in order to investigate the possible superiority in designing related optical sensors. In our research, it is interesting to find that our probe has the different properties compared with the similar reported probe bearing the coumarin fluorophore. The novel fluorescent probe (CSO–CN) was demonstrated to be able to detect HSO 3 − ions and changes in viscosity with a good resistance to oxidizers. The probe offers high sensitivity (LOD = 0.149 μM) for detecting HSO 3 − via the Michael addition reaction. It also enables fluorescence emission at 483 nm and the tracking of viscosity alternation by impeding the twisted intramolecular charge transfer (TICT) mechanism. Besides, the dual-functional probe has effectively been utilized to monitor HSO 3 − level in living cells, zebrafish and real food samples. [Display omitted] • Thienocoumarin based fluorescence probes that could specific detect bisulfite and viscosity. • Rapid, highly sensitive and highly selective detections in aqueous solutions. • Probe is oxidizer-resistant. • Probe can be used for imaging bisulfite in biosystems and real foods. [ABSTRACT FROM AUTHOR]

Bisulfite (HSO 3 −) serves as a bleaching agent, antioxidant, antimicrobial, and regulator of enzymatic reactions in biosystem. However, abnormal levels of bisulfite can be detrimental to health. Hypochlorous acid (HOCl), which acts as bioactive small molecules, is crucial for maintaining normal biological functions in living organisms. Disruption of its equilibrium can lead to oxidative stress and various diseases. Therefore, it's essential to monitor the fluctuations of HOCl and HSO 3 − at cellular and in vivo levels to study their physiological and pathological functions. This study constructed a novel NIR bifunctional colorimetric fluorescent probe using thienocoumarin-indanedione structures to identify hypochlorite (ClO−) and bisulfite (HSO 3 −). By using CSO-IO to recognize HSO 3 − and HOCl, two distinct products were generated, displaying green and blue fluorescence, respectively. This property effectively allows for the simultaneous dual-functional detection of HSO 3 − (LOD: 113 nM) and HOCl (LOD: 43 nM). In this work, the biocompatible molecule CSO-IO has been effectively designed to detect HOCl/HSO 3 − in living cells and zebrafish. As a result, the dual-functional fluorescent probe has the potential to be utilized as a molecular tool to detect HSO 3 − derived compounds and HOCl simultaneously within the complex biological system. [Display omitted] • A NIR fluorescence probe that specific detect bisulfite and hypochlorous acid. • Rapid, highly sensitive and highly selective detections in aqueous solutions. • Probe can be used for monitoring bisulfite and HOCl level in biosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel fluorescent probe for highly specific and visible detecting hydrogen sulfide and bisulfite was developed. • The probe displayed significance dual-channel spectral behavior for hydrogen sulfide and bisulfite detection. • The probe was made into portable test strips for detecting hydrogen sulfide and bisulfite. A novel fluorescent probe was developed for simultaneously detection of hydrogen sulfide and bisulfite. The probe underwent remarkable turn on fluorescence response and significantly different UV–vis spectral changes in the presence of hydrogen sulfide or bisulfite with different response rates. As a result, this probe could be a potential candidate for imaging of hydrogen sulfide and bisulfite in vivo. [ABSTRACT FROM AUTHOR]

Here in, a system of Co 3 O 4 /CoO catalyst activated with the aid of bisulfite (NaHSO 3) was established for the decomposition of methylene blue (MB). The Co 3 O 4 /CoO material was designed by a two-step uniform precipitation and calcination method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy to detect the crystallinity, morphology, magnetic ability, element valence and the different types of free radicals, respectively. The efficient degradation of MB relies on the synergistic effect between the Co 3 O 4 /CoO catalyst and bisulfite (NaHSO 3) to generate some strongly oxidizing radicals, which could achieve a MB degradation rate of 90.7% within 40 min using this novel system. Additionally, the ferromagnetic property of Co 3 O 4 /CoO catalyst is expected to supply an excellent magnetic separation ability to help separate the solid catalyst from the aqueous solution. The novel catalyst system of Co 3 O 4 /CoO/NaHSO 3 may serve as a promising new system for wastewater treatment. • Co 3 O 4 /CoO was synthesized to activate NaHSO 3 for fast methylene blue degradation. • Vibrating sample magnetometer showed the magnetic property of Co 3 O 4 /CoO. • Co 3 O 4 /CoO composite was easily separated from solution by an external magnet. • SO 4.•- and •OH were confirmed as active radicals in the Co 3 O 4 /CoO/NaHSO 3 system [ABSTRACT FROM AUTHOR]

This work presented a FRET-ICT based fluorescent probe (named NTC) composed of coumarin-benzothiazole as the acceptor and 4-nitrobenzo[ c ][1,2,5] oxadiazole (NBD) as the donor for the detection of SO 2 derivatives in NIR. Probe NTC possessed superior performance including selectivity, quickly response toward SO 3 2−/HSO 3 − and high energy transfer efficiency (94 %). The test strips provided a simple and effective tool in detecting the presence of bisulfite. Besides, NTC was applied to test the sulfur dioxide derivatives in food samples and cells. [Display omitted] • A NIR ratiometric fluorescent probe NTC was developed to detect sulfur dioxide derivatives. • NTC had a large Stokes shift of 150 nm and 94 % energy transfer efficiency. • NTC possessed good selectivity and sensitivity toward sulfur dioxide derivatives. • NTC was applied to detect sulfur dioxide derivatives in test strips, food samples and cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel fluorescent probe compatible with GDME device was prepared. • A GDME-FL method was developed to detect HSO 3 −. • The method has been successfully applied for food analysis. • The Lens cleaning paper were first used for imaging research. • The probe shows high response speed, selectivity and sensitivity toward free bisulfite/sulfite anions. Excessive residues of sulfite (SO 3 2−) have negative effects on human health; thus, it is important to monitor SO 3 2− levels in food samples and living cells. In this study, a novel fluorescent probe (E)-4-(2-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl) vinyl) −1,1-dimethyl-1H-benzo[e]indol-3-ium-3-yl) butane-1-sulfonate (probe 1) was prepared. This probe was based on a conjugated coumarin–benzindolium system that was detected to exhibit high-response speed and selectivity and sensitivity towards free bisulfite/sulfite (HSO 3 −/SO 3 2−) anions. Probe 1 was also highly compatible with gas-diffusion microextraction (GDME) because of its good water solubility, reaction rapidness and ratiometric signal response. Extraction and detection tasks could be completed within 30 min under the selected experimental conditions. The developed GDME-FL method showed adequate limits of detection (4.9 μM) and quantification (16.2 μM) for food analysis. The applications of this method for the detection of free HSO 3 − in product samples were investigated thoroughly. In addition, we successfully applied probe 1 to image lens cleaning paper, onion, Daphnia magna and HeLa cells. Therefore, probe 1 has a promising application potential for measuring the HSO 3 −/SO 3 2− content of real food samples. [ABSTRACT FROM AUTHOR]

• Reduction of p-nitrophenol by ZVI was greatly enhanced by bisulfite under anoxic condition. • Bisulfite could dissolve some iron oxide on the ZVI surface and accelerate the reduction of Fe(III) to Fe(II). • Bisulfite can be used as a cost-effective and environmental-friendly additive to enhance the reduction activity of ZVI. Zero-valent iron (ZVI) is widely used in the field of wastewater treatment and groundwater remediation, but it suffers from low reactivity due to the surface passivation layer. In the present work, bisulfite was used as an additive to enhance the reduction activity of ZVI under anoxic conditions. It was found that the reaction kinetic constant of p-nitrophenol reduction in ZVI/bisulfite process was approximately 132 times higher than that by ZVI alone. Bisulfite could dissolve and reduce some iron oxide on the ZVI surface, resulting in the exposure of more active sites like Fe0 and Fe(II) for p-nitrophenol reduction through direct electron transfer. Common substances in water had no effects on p-nitrophenol degradation by ZVI/bisulfite process, but phosphate suppressed ZVI corrosion seriously. This work provides a simple, cost-effective and environmental-friendly method to improve the reducing activity of ZVI under anoxic conditions. [ABSTRACT FROM AUTHOR]

Maintaining redox homeostasis in organisms plays a crucial role in human life and health, and changes in the levels of SO 2 and H 2 O 2 , as typical representative substances of reductants and oxidants, directly affects intracellular redox homeostasis. Hence, it is necessary to manufacture fluorescent probes that can detect HSO 3 − and H 2 O 2. In this work, a benzopyrylium salt containing benzothiazole derived fluorescent probe HBTO-H with dual properties of aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) has been developed. The probe displays rapid and reversible test of HSO 3 − and H 2 O 2 in DMF/Tris (v:v = 2:8, pH = 7.3, Tris 10 mM) mixed solvent with high selectivity, good anti-interference ability and a wide applicable pH range (6–11). The detection limits of HBTO-H for HSO 3 − and H 2 O 2 are 0.187 μM and 0.152 μM, respectively. The response mechanisms of HBTO-H toward HSO 3 − and H 2 O 2 have been demonstrated to be Michael addition reaction and its retro-reaction based on 1H NMR and HRMS analyses. In addition, HBTO-H has been successfully applied to check HSO 3 − in sugar and wine specimens. Moreover, HBTO-H was proved to be mitochondria-targetable and can alternately detect exogenous HSO 3 − and H 2 O 2 in MCF-7 cells, which is desired to be applied to trace HSO 3 − in organisms in the future. [Display omitted] • A simple "AIE + ESIPT" mechanism-based fluorescent probe HBTO-H has been developed. • HBTO-H displays rapid (time <1 min) and reversible detection of HSO 3 − and H 2 O 2. • HBTO-H has high selectivity and anti-interference along with low detection limit. • HBTO-H can be applied to detect HSO 3 − in food samples. • HBTO-H possesses mitochondria-targeting function. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO 2) had been recognized as an environmental pollutant produced from industrial processes. SO 2 is water soluble and forms hydrated SO 2 (SO 2 ·H 2 O), bisulfite ion (HSO 3 −), and sulfite ion (SO 3 2−) upon dissolution in water. SO 2 could be also produced endogenously from sulfur-containing amino acids l -cysteine in mammals. Endogenous SO 2 can maintain the balance of biological sulfur and redox equilibrium in vivo , regulate blood insulin levels and reduce blood pressure. Excess intake of exogenous SO 2 can result in respiratory diseases, cardiovascular diseases and neurological disorders. As a result, fluorescent probes to detect HSO 3 −/SO 3 2− have attracted great attention in recent years. Herein, a general overview was provided with the aim to highlight the typical examples of the HSO 3 −/SO 3 2− fluorescent probes reported since 2010, especially those in the past five years. We have classified HSO 3 −/SO 3 2− fluorescent probes through different chemical reaction mechanisms and wish this review will give some help to the researchers in this field. Image 1 • 84 different reaction-based fluorescent probes for HSO 3 −/SO 3 2− have been summarized. • These fluorescent probes have been divided into helpful categories according to the chemical mechanism of detection. • The two tables and one figure in the end summarize the entire contents. • This review also provides interesting insights for future developments of fluorescent probes for HSO 3 −/SO 3 2−. [ABSTRACT FROM AUTHOR]

• The ferrocene-based probe colourimetricaly/electrochemicaly sensed HSO 3 − in a 95 % aqueous solution. • Mechanism of sensing was illustrated by 1H & 13C NMR, HR-MS and DFT/TD-DFT analysis. • The plausible mechanism of sensing is via nucleophilic addition of HSO 3 − ion to olefinic C-atom. • The proposed sensing mechanism was well supported by DFT/TD-DFT calculations. • The probe was utilized to estimate the levels of HSO 3 − ions in natural water and red wine samples. A simple ferrocene-based organic probe (AK5) is described for selective and sensitive colourimetric/electrochemical detection of HSO 3 - ions in a 95 % aqueous solution. Upon adding HSO 3 − ions, the colour of the solution changes from brown to colourless instantaneously. The plausible mechanism of detection of HSO 3 − ions by AK5 was illustrated by 1H NMR, 13C NMR, HR-MS and DFT/TD-DFT analysis, which revealed nucleophilic addition of HSO 3 − ion to olefinic C-atom. The limits of detection (LOD) are determined to be 5.58 and 0.12 µM in colourimetric and electrochemical methods, respectively. The probe is successfully applied to estimate the levels of HSO 3 − ions in natural water and red wine samples. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe TPN-DP was developed for the detection of HSO 3 −. • TPN-DP exhibited high sensitivity, and excellent selectivity for HSO 3 −. • Real-time imaging of HSO 3 − was successfully achieved in plant and zebrafishes. Sulfur dioxide (SO 2) and its derivative bisulfite (SO 3 2−/HSO 3 −) have a serious impact on the human health and environment. Therefore, the development of highly sensitive and specific detection methods for SO 2 and its derivative is of great significance for environmental monitoring, food safety, and related disease research. In this paper, probe TPN-DP based on the triphenylamine fluorophore was developed to enable the imaging and detection of HSO 3 − in plant and zebrafish. In PBS buffer solution, the designed probe TPN-DP can react with HSO 3 − by highly selective nucleophilic addition reaction, leading to a sensitive change in the color of probe TPN-DP solution from pink to colorless. The changes in fluorescence and color can be easily recognized by the naked eye. Moreover, probe TPN-DP exhibited a fast response time of 8 min, high sensitivity of 19.4 nM, and excellent selectivity for sensing HSO 3 −. With the help of probe TPN-DP, the detection of HSO 3 − was successfully achieved in water sample and various biological systems, including onion epidermal cells, tobacco seedling roots, and zebrafish. These findings not only provide valuable insights into the biological role of HSO 3 − but also offer a promising analytical method for efficient HSO 3 − recognition. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, the research on bisulfite (BS) activation by Mn(II) is very limited probably because of the low catalytic efficiency of Mn(II). Adding ligands to Mn(II)/BS system is likely to improve the BS activation, but the relative information is very rare. Therefore, the effect of nitrilotriacetic acid (NTA) on Mn(II)/BS system was investigated in this work using sulfamethoxazole (SMX) as the target contaminant. The results showed that the addition of NTA enhanced SMX removal in Mn(Ⅱ)/BS system through forming Mn(Ⅱ/III)-NTA complexes driving Mn(III)/Mn(II) cycle and stabilizing Mn(III). Alcohol scavenging experiments and competitive kinetic experiments indicated that sulfate radical (SO 4 •−) and hydroxyl radical (HO•) were not the main reactive species in Mn(II)/NTA/BS system. Mn(Ⅲ) was the primary oxidant for SMX elimination in this system and its existence was proved by UV-Vis absorption spectrum of reaction solution. Mn(Ⅱ)/NTA/BS system could greatly degrade SMX in near-neutral conditions, while nearly no SMX removal was observed at pH 3.0. The decrease of dissolved oxygen concentration significantly inhibited BS autocatalytic stage, thus suppressing the removal of SMX. Due to the competitive complexation of HCO 3 − and FA with NTA for Mn(II), their addition in Mn(Ⅱ)/NTA/BS system obviously inhibited SMX degradation. Four intermediates were detected during SMX degradation in Mn(Ⅱ)/NTA/BS system, and the possible SMX transformation pathways were speculated as N-S bond breaking, hydroxylation, amino oxidation and coupling reaction. [Display omitted] • The addition of NTA in Mn(II)/BS system significantly enhanced SMX degradation. • NTA drived Mn(III)/Mn(II) cycle and stabilized Mn(III) by complexing with Mn(II/III). • Mn(Ⅲ) was the primary oxidant for SMX removal in Mn(II)/NTA/BS system. • Near-neutral condition was more beneficial to SMX removal than strongly acidic pH. • DO was essential for Mn(III) formation and BS autocatalysis in Mn(II)/NTA/BS system. [ABSTRACT FROM AUTHOR]

• The FRI values of HA decreased obviously after PM/BS pre-oxidation. • The UV-absorbing parts of HA were not impacted significantly by PM/BS process. • PM/BS process reduced the formation of DCAN and 1,1,1-TCAce from all NMW fractions. • With 150 μg/L Br- , PM/BS process reduced the total risk value of DBPs by 14%. • For natural water samples, PM/BS process changed the total ITRVs by <8%. Bisulfite-activated permanganate oxidation (PM/BS) technology is an emerging oxidation process that can rapidly oxidize organic contaminants and degrade some permanganate-resistant organic contaminants. For the first time, the influences of PM/BS technology as a pre-oxidation process on the formation potentials of disinfection by-products (DBPFPs) during chlorination of humic acid (HA) solution and three natural water samples were investigated. The results revealed that PM/BS pre-oxidation only slightly affected the DBPFPs of HA in the absence of Br- although it changed the structure of HA according to the fluorescence characterization result. With the presence of Br-, PM/BS pre-oxidation enhanced the generation of trihalomethanes but inhibited that of nitrogenous DBPs (N-DBPs) during chlorination of HA. The toxic risk analysis showed that the toxicity of the generated DBPs from chlorinating HA solution without Br- only changed slightly after PM/BS pre-oxidation but it was decreased by 14% in the presence of 150 μg/L Br− due to PM/BS pre-oxidation. This should be associated with the inhibiting effect of PM/BS pre-oxidation on the generation of N-DBPs and several haloacetic acids in the presence of Br-. Because of the complex matrix of natural water samples, PM/BS pre-oxidation had minor influence on the amount and the potential toxicity of DBPs generated during chlorination. The above results suggested that PM/BS technology could be an alternative of the drinking water pretreatment. [ABSTRACT FROM AUTHOR]

The homogeneous Fe(VI)/Na 2 SO 3 system has been proposed for highly efficient degradation of recalcitrant contaminants, in which sulfite could significantly enhance the transformation of organic substrate by Fe(VI). Also, the Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH conditions. The degradation rates reached up to 80% within 2 min and 70% within 5 min in strongly acidic and alkaline conditions, respectively. Unexpectedly, a faster removal rate was obtained in Fe(VI)/NaHSO 3 system than that in Fe(VI)/Na 2 SO 3 system for the degradation of methylene blue (MB). A reasonable dye degradation mechanism was proposed and verified by a series of experiments. The high oxidation potential of Fe(VI) and other species such as sulfate and hydroxyl radicals were responsible for the outstanding capabilities of Fe(VI)/NaHSO 3 system, which could significantly improve the treatment of organics in wastewater under a very wide range of pH conditions. Image 1 • Homogeneous Fe(VI)/Na 2 SO 3 system was developed for degradation of contaminants. • Sulfite significantly enhanced the transformation of organic substrate by Fe(VI). • The Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH. • Dye degradation rates reached up to 80% within 2 min in strongly acidic conditions. [ABSTRACT FROM AUTHOR]

Organophosphorus pesticides (OPPs), a kind of effective insecticide, have attracted extensive attention of researchers because of the high toxicity and refractory character of their degradation products. Given the ubiquity of manganese dioxide (MnO 2) and bisulfite (HSO 3 −) in environmental media, the abiotic degradation of several typical OPPs by the MnO 2 -HSO 3 - reaction system was investigated in batch experiments. As a representative OPP, methyl parathion (MP) was chosen to be the focus of the study. The removal rate of MP was remarkably improved by adding bisulfite (HSO 3 −) to the MnO 2 single-reaction system, and the oxidation product methyl paraoxon was below the detection limit. The primary active substances generated from the reaction system were determined to be Mn(III) species by adding excess radical scavengers or complexants (methanol and pyrophosphate) to the reaction system. On the basis of the metabolic products of MP identified by liquid chromatography–high-resolution mass spectrometry (LC/HRMS) and gas chromatography–mass spectrometry (GC/MS), the transformation pathway of MP in the MnO 2 -HSO 3 - reaction system was elicited, which included the predominant processes of hydrolysis and oxidation. Furthermore, the typical OPPs with different structures were also degraded efficiently by the reaction system because of the oxidative degradation of Mn(III). This study offers significative information related to the abiotic oxidation of manganese minerals and the fate and dissipation of OPPs in the actual environment. Image 1 • HSO 3 − significantly enhanced the abiotic degradation of methyl parathion by MnO 2. • The primary active substance was determined to be Mn(III) in the MnO 2 -HSO 3 - reaction system. • Transformation pathway of MP was elicited according to the identified products. • Many OPPs with different structures were also degraded efficiently by the reaction system. [ABSTRACT FROM AUTHOR]

Cyanide and bisulfite are hypertoxic even in low concentration. The development of convenient methods of the detection of analyte is critically important. In this paper, the dual ions fluorescent probe CIM with superior water-solubility has been designed and synthesized with low detection limits of 0.35 μM (for CN− with a linear relationship of 0.996) and 23 nM (for HSO 3 − with a linear relationship of 0.993). Modest pH moderation could be easily used to detect the CN− and HSO 3 − without reciprocal interference. The specific detection is not interfered with other potential coexisted species. The possible recognition mechanism between probe and analytes is illustrated by NMR, HRMS and computational simulation. Both analytes undergo 1, 4-addition reaction on the ethenyl of the probe, which is rare in lots of previous work and results in a fluorescent color change. Image 1 • The dual fluorescent probe CIM has superior water-solubility. • The detection limits of cyanide and bisulfite are separately 3.5 × 10−7 M and 2.3 × 10−8 M. • pH moderation could be used to detect CN− and HSO 3 − without reciprocal interference. • The reaction mechanism is investigated by 1H NMR spectra, HRMS and theoretical calculation. • 1,4-addition on the probe is supported by the simulated absorption spectra and emission spectra. [ABSTRACT FROM AUTHOR]

Abstract To improve the efficiency of traditional advanced oxidation processes (AOPs), a novel photo-assisted heterogeneous Fenton-like process was proposed and verified by experiments. Under visible light, NaHSO 3 and transition metal composite oxide MnO 2 /NiO were tested together for degradation of orange II (OII). MnO 2 /NiO nanocomposites were prepared by a hydrothermal method using different nickel oxide to manganese oxide ratios and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–vis (UV–vis) diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The best MnO 2 /NiO nanocomposite (Ni:Mn = 1:2) which was designated as Ni-Mn-3 showed the best OII removal efficiency of about 92.8% among the various MnO 2 /NiO nanocomposites of different Ni:Mn ratios. Moreover, the best catalyst, Ni-Mn-3 also showed good stability and recovery performance for degrading OII. The degradation ability of Ni-Mn-3 decreased no more than 10% after three times of repeated tests, which makes it more competitive in practical industrial applications than other heterogeneous Fenton-like catalysts. Graphical abstract Image 1 Highlights • New photo-assisted heterogeneous Fenton-like process was used with MnO 2 /NiO catalysts. • Key novelty was the use of NaHSO 3 to activate MnO 2 /NiO under visible light. • The MnO 2 /NiO (Ni:Mn = 1:2) showed the best Orange II removal efficiency of about 92.8%. • 1Ni:2Mn oxide showed good stability and recycling performance for degrading Orang II. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Bisulfite drastically enhanced the degradation of bisphenol A in Fe3+-H 2 O 2 system. • Complexing and reducing effects of bisulfite accelerated the Fe3+/Fe2+ cycle. • OH was the major reactive species for BPA degradation in Fe3+-HSO 3 −-H 2 O 2 system. • Fe3+-HSO 3 −-H 2 O 2 system may act as a followed stage of Fe2+-H 2 O 2 system. Abstract The present work aimed at using bisulfites (HSO 3 −) to enhance the oxidative degradation of bisphenol A (BPA) in a Fenton process based on the Fe3+-H 2 O 2 reagents. It was confirmed that both the degradation and mineralization of BPA were drastically enhanced by the addition of HSO 3 −. Typically, the use of 0.1 mmol L−1 Fe3+, 0.3 mmol L−1 HSO 3 − and 10 mmol L−1 H 2 O 2 achieved a complete degradation of BPA (0.05 mmol L−1) in only 2 min. The addition of HSO 3 − increased the BPA degradation rate constant from 0.045 min−1 in the Fe3+-H 2 O 2 system to 2.71 min−1 in the Fe3+-HSO 3 −-H 2 O 2 system by 60 times. This drastic enhancement effect of HSO 3 − was attributed to its complexing and reducing abilities. The formation of FeSO 3 + complex prevented the precipitation of Fe3+ and accelerated the cycling of Fe3+/Fe2+; the reducing ability of HSO 3 − further favored the transformation of Fe3+ to Fe2+. Several reactive species, including OH, SO 3 − and SO 4 − were responsible for the degradation of BPA, among which OH was the dominant one. The proposed Fe3+-HSO 3 −-H 2 O 2 system is suggested be able to act as the followed stage of a traditional Fe2+-H 2 O 2 system in the engineering setting. [ABSTRACT FROM AUTHOR]

Abstract An abnormal level of bisulfite can induce toxicological effects associated with lung cancer, cardiovascular and neurological disorders. Therefore, it is of significance to develop an effective fluorescent probe to detect bisulfite in living cells. Herein, a novel fluorescent probe QPCT , based on a 1,4-addition mechanism, was constructed for the colorimetric and ratiometric detection of bisulfite. QPCT displayed high selectivity and anti-interference ability to bisulfite over other anions and biothiols. The probe renders a sensitive ratiometric response to bisulfite with a remarkable fluorescence blue shift from 590 to 537 nm and the fluorescence ratio was linear with bisulfite concentration over the range of 0–120 μM. More importantly, QPCT has been successfully applied to detect bisulfite in sugars and living A549 cells, which indicated that QPCT had a great capability for monitoring bisulfite in complex systems. Graphical abstract A novel fluorescent probe QPCT for the colorimetric and ratiometric detection of HSO 3 − was constructed and successfully applied for sugar analysis as well as imaging in living A549 cells. Image 1 Highlights • QPCT displays a colorimetric and ratiometric response towards HSO 3 −. • QPCT exhibits good selectivity to HSO 3 − among various anions and biothiols. • QPCT has been successfully applied to detect HSO 3 − in real samples and living cells. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • HSO3- enhanced the oxidation of contaminants by MnO2 significantly. • Mn(III) was the main active species in the MnO2/HSO3- (MO/BS) process. • Proper MnO2/HSO3- molar ratio was critical for efficient removal of contaminants. • Coexisting solutes influence the performance of MO/BS process in different ways. • The oxidation of contaminants by Mn(III) was possibly via electrophilic attack. Abstract Colloidal MnO 2 is the most reactive phase of Mn(IV) while HSO 3 − is a common reductant in water treatment. This study shows that the presence of HSO 3 − resulted in significant increase in the decomposition rate of organic contaminants by colloidal MnO 2. The degradation rate of contaminants in the MnO 2 /HSO 3 − process dropped with elevating pH and a proper MnO 2 /HSO 3 - molar ratio was critical for efficient decomposition of contaminants. The time-resolved spectroscopy of manganese species, the influence of pyrophosphate on UV absorbance spectra, and the relative rate constants of contaminants oxidation in MnO 2 /HSO 3 − process suggested that the synergetic effect of HSO 3 − and colloidal MnO 2 arose from the generation of Mn(III) aq , which could oxidize contaminants rapidly. The presence of pyrophosphate, ethylenediaminetetraacetic acid, and humic acid depressed the degradation of contaminants in MnO 2 /HSO 3 − process by complexing with Mn(III) aq , buffering the solution or competing with contaminants for Mn(III) aq , and/or inhibiting the consumption of bisulfite. However, Ca2+ and Mg2+ accelerated the oxidation of contaminants in MnO 2 /HSO 3 - process by enhancing the reduction of MnO 2 by HSO 3 -. The good negative correlation of the O/N or H Mulliken charges of organic contaminants with their removal in MnO 2 /HSO 3 − process suggested that organic contaminants were oxidized by Mn(III) aq via electrophilic attack. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel Ce(IV)/HSO 3 − process was proposed firstly in this study. • Carbamazepine (CBZ) could be oxidized at pH ini 3.0–7.0 in Ce(IV)/HSO 3 − process. • SO 4 −, HO, and SO 5 − were identified to be reactive species in this process. • SO 4 − played a major role in the degradation of CBZ in Ce(IV)/HSO 3 − system. • Pathways of CBZ degradation in Ce(IV)/HSO 3 − process were proposed. Abstract In this study, the activation of bisulfite by cerium(IV) (Ce(IV)/HSO 3 − process) is proposed for the first time to degrade organic contaminants. Experiments show that carbamazepine (CBZ), a representative recalcitrant contaminant of emerging concern, is oxidized by Ce(IV)/HSO 3 − treatment at pH ini 3.0–7.0 when O 2(aq) is present to promote HSO 3 − autoxidation. SO 4 −, HO, and SO 5 − were identified as active oxidants of CBZ based on the ESR spectra and the results of alcohol quenching experiments. Quantitative analysis indicates that SO 4 − plays a major role, while HO and other species play minor roles in the degradation of CBZ in the Ce(IV)/HSO 3 − process. SO 4 − radicals are derived from the reaction of SO 5 − with HSO 3 − and the activation of hydrogen peroxomonosulfate (HSO 5 −) by Ce(IV). Five degradation pathways of CBZ are proposed based on transformation products identified by UPLC-QToF-MS/MS, and proposed sites for radical attack are supported by the results of frontier electron density calculations. Elevated concentrations of Cl−, Fe(III), and humic acid (HA) inhibit CBZ degradation, while other non-target solutes have minimal effects on CBZ degradation in the Ce(IV)/HSO 3 − process. Finally, experiments demonstrating degradation of a suite of other organic contaminants suggests that the Ce(IV)/HSO 3 − system can be applied as a new advanced oxidation process for wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract A new dual-site fluorescent probe (probe 1) was synthesized for the separate detection of hydrogen sulfide and bisulfite. Probe 1 exhibited a rapid response to H 2 S and HSO 3 − through two emission wavelengths and color changes, and displayed satisfactory sensitivity. Probe 1 changed color in response to various concentrations of H 2 S, while probe 1 test paper changed gradually from colorless to pink. With HSO 3 − addition, there was almost no color change. Furthermore, the presence of HSO 3 − does not affect the detection of H 2 S; however, the presence of H 2 S interferes with the detection of HSO 3 −. Hence, quantitative detection of HSO 3 − must occur in an H 2 S-free environment. The results indicate that probe 1 is suitable for use as a sensor for hydrogen sulfide detection. Graphical abstract A dual-site fluorescent probe was designed and synthesized for separate detection of hydrogen sulfide and bisulfite. Image 1 Highlights • A dual-site fluorescent probe was developed for separate detection of hydrogen sulfide and bisulfite. • The fluorescent probe reacted with various concentrations of H 2 S and produced gradual color changes. • With increasing H 2 S concentration, the color of probe 1 test paper changed gradually from colorless to pink. • The probe was successfully applied to the qualitative and quantitative detection of H 2 S in real water samples. [ABSTRACT FROM AUTHOR]

Abstract A new colorimetric fluorescent probe 1 contained a C˭C double bond for the detection of bisulfite (HSO 3 -) via Michael-Addition was developed. Significantly, probe 1 can detect HSO 3 - with excellent selectivity, high sensitivity, fast response (< 10 min) and low detection limit (21 nM). Furthermore, the live cell imaging results provided a powerful method to study HSO 3 - chemistry in biological systems. [ABSTRACT FROM AUTHOR]

Abstract A series of compound oxides of Fe-MnX (Fe-Mn1, Fe-Mn2, Fe-Mn3, Fe-Mn4) were synthesized and tested in the activation of bisulfite for methylene blue (MB) degradation in aqueous solution under dark condition. X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area were used to characterize the Fe-MnX oxides. Fe-Mn2 could remove about 92% of MB from solution in 70 min, which was much more than the amounts removed by either Fe 2 O 3 or MnO 2. Mechanism analysis of synergistic effects was validated by simple detection of ionic species such as, Fe (III), Fe (II) and Mn (III) and controlling different variables. After thermal treatment, the current catalysts could be regenerated and recycled for at least three times. [ABSTRACT FROM AUTHOR]

A fluorescent probe is constructed to quickly and accurately detect bisulfite. The detection mechanism was considered to operate via the bisulfite, causing deprotonation of amido bond of 8-aminoquinoline derivative leading to fluorescence enhancement. The probe has a good selectivity for bisulfite over the other competitive substances such as F − , Cl − , Br − , I − , C 2 O 4 2− , NO 2 − , ClO 4 − , OAc − , PO 4 3− , CO 3 2− , HCO 3 − , HS − , HSO 4 − , SCN − , SO 4 2− , S 2 O 3 2− , Cys, Hcy and GSH. There is a good linear relationship between fluorescence intensity and the concentration of bisulfite in the range of 0–200 μM. The limit of detection was calculated to be 0.61 μM. Furthermore, the probe has also been successfully used for imaging bisulfite in living cells. [ABSTRACT FROM AUTHOR]

We report the development of a bifunctional near-infrared fluorescent probe (QZB) for selective sensing of bisulfite (HSO 3 −) and hypochlorous acid (HOCl). The synergistic detection of HSO 3 − and HOCl was achieved via a C=C bond recognition site. In comparison with the red-fluorescence QZB , two different products with non-fluorescence and paleturquoise fluorescence were produced by the recognition of QZB towards HSO 3 − and HOCl respectively, which can realize effectively the dual-functional detection of HSO 3 − and HOCl. QZB features prominent preponderances of dual-function response, near-infrared emission, reliability at physiological pH, low cytotoxicity and high sensitivity to HSO 3 − and HOCl. The detection of HSO 3 − in actual food samples has been successfully achieved using QZB. Utilization of QZB -based test strip to semi-quantitatively detect HSO 3 − and HOCl in real-world water samples by the "naked-eye" colorimetry are then demonstrated. Simultaneously, the determination of HSO 3 − and HOCl in real-world water sample has been achieved by smartphone-based standard curves. Additionally, the applications of QZB for imaging HSO 3 − and HOCl in vivo are successfully demonstrated. Consequently, the successful development of QZB could be promising as an efficient tool for researching the role of HSO 3 −/HOCl in the regulation of redox homeostasis regulation in vivo and complex signal transduction and for future food safety evaluation. A bifunctional near-infrared fluorescent probe (QZB) was developed for selective sensing of HSO 3 − and HOCl by two different fluorescence signals. QZB features near-infrared emission, low cytotoxicity and high sensitivity. The detection of HSO 3 − in actual food samples has been successfully achieved using QZB. Utilization of QZB -based test strip to semi-quantitatively detect HSO 3 − and HOCl in real-world water samples by the "naked-eye" colorimetry are then demonstrated. Simultaneously, the determination of HSO 3 − and HOCl in real-world water sample has been achieved by smartphone-based standard curves. Additionally, the applications of QZB for imaging HSO 3 − and HOCl in vivo are successfully demonstrated. [Display omitted] • A bifunctional probe (QZB) has been successfully developed for the detection of HSO 3 − and HOCl. • QZB features advantages of near-infrared emission, reliability at physiological pH, low cytotoxicity and high sensitivity. • The quantitative determination the levels of HSO 3 − and HOCl in real-world water samples has been achieved under the assistance of smartphone. • The imaging HSO 3 − and HOCl in vivo using QZB are successfully demonstrated. [ABSTRACT FROM AUTHOR]

A near-infrared fluorescent probe LJ was rationally constructed for sensing HSO 3 −. The fluorescence quenching recognition mechanism was realized by the addition reaction of electron-deficient C C bond in probe LJ and HSO 3 −. Probe LJ revealed multifarious preponderances such as longer wavelength emission (710 nm), low cytotoxicity, larger Stokes shift (215 nm), better selectivity, higher sensitivity (72 nM) and short response time (50 s). Encouragingly, probe LJ can detect HSO 3 − in living zebrafish and mice in vivo by fluorescence imaging techniques. Probe LJ was also successfully employed to semi-quantitatively detect HSO 3 − in real foodstuff samples by "naked-eye" colorimetriy. More importantly, quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. [Display omitted] • Probe LJ has many advantages such as near-infrared emission, short response time and reliability in a wide range of pH. • Probe LJ was successfully employed for the fluorescence imaging of HSO 3 − in live zebrafish and mice in vivo. • Semi-quantitative analysis of HSO 3 − in food and water samples has been realized by "naked-eye" colorimetry using probe LJ. • Quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. Bisulfite (HSO 3 −) has been widely used as an antioxidant, enzyme inhibitor and antimicrobial agent in foodstuffs, pharmaceutical and beverages industries. It is also a signaling molecular in the cardiovascular and cerebrovascular systems. Nevertheless, a high level of HSO 3 − can cause allergic reactions and asthmatic attacks. Accordingly, the monitoring of HSO 3 − levels possesses momentous significance from the perspectives of biological technology and food security supervision. Herein, a near-infrared fluorescent probe LJ is rationally constructed for sensing HSO 3 −. The fluorescence quenching recognition mechanism was realized by the addition reaction of electron-deficient C C bond in probe LJ and HSO 3 −. Probe LJ revealed multifarious preponderances such as longer wavelength emission (710 nm), low cytotoxicity, larger Stokes shift (215 nm), better selectivity, higher sensitivity (72 nM) and short response time (50 s). Encouragingly, probe LJ can detect HSO 3 − in living zebrafish and mice in vivo by fluorescence imaging techniques. In the meantime, probe LJ was also successfully employed to semi-quantitatively detect HSO 3 − in real foodstuff samples and water samples by the "naked-eye" colorimetry without the help of any special instruments. More importantly, quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. Consequently, probe LJ is expected to provide an effective and convenient way for the detection and monitoring of HSO 3 − in organisms and for food safety detection, which has tremendous application potential. [ABSTRACT FROM AUTHOR]

Bifunctional fluorescent probes for recognizing different substances have important research significance due to the wide variety of analytes. Here, a triphenylamine structural fluorescent probe (TPA-CHO) for the recognition of hydrazine (N 2 H 4) and bisulfite (HSO 3 -) in environment and lipid droplets based on aldehyde group sensing site was developed. The probe can detect those analytes with low detection limits and distinguishable color change (0.24 µM, red to green for N 2 H 4 ; 1.71 µM, red to blue for HSO 3 -). The reaction mechanism indicates that after reacting with N 2 H 4 and HSO 3 -, the production of hydrazone or hydroxy methanesulfonate group leads to a different molecular length and intramolecular charge transfer degree and then induces color-differentiated fluorescence emission. This structural design strategy for bifunctional fluorescent probes provides essential ideas for the design of single-molecule dual-analyte target probes. [Display omitted] • A triphenylamine fluorescent probe for N 2 H 4 /HSO 3 - was developed. • The probe can detect N 2 H 4 /HSO 3 - with distinguishable color change. • Aldehyde reacts with N 2 H 4 /HSO 3 - producing hydrazone or methanesulfonate group. • The probe can distinctively recognize N 2 H 4 /HSO 3 - in lipid droplets. [ABSTRACT FROM AUTHOR]

Bisulfite-activated permanganate (S(IV)/Mn(VII)) process has proven to be a promising method for rapidly degrading micropollutants. Previous studies have shown that the treatment efficiency of the S(IV)/Mn(VII) process suffer from significant water matrix effects while the mechanism still remains unclear. This study systematically investigates the influence of chloride, which is a common water constituent, on the S(IV)/Mn(VII) process. Addition of chloride decreased the removal of methyl phenyl sulfoxide, phenol, benzoic acid and carbamazepine by the S(IV)/Mn(VII) process but increased dimethoxybenzene removal. The distribution of reactive species in the S(IV)/Mn(VII) process in the absence and presence of chloride was determined with relative rate method. The S(IV)/Mn(VII) process primarily relies on SO 4 •− and reactive manganese species (RMnS) for pollutant abatement while dosing chloride decreased the concentration of these reactive species. Reactive chlorine species (RCS), such as Cl 2 •– and ClO•, are formed through the reaction of SO 4 •– with chloride, and become more important at high concentrations of chloride. RMnS includes Mn(VI), Mn(V) and Mn(III), but none of these species are capable of oxidizing chloride. However, chloride retarded the consumption of bisulfite which reduced RMnS and RCS in turn. DOM inhibited pollutant removal by the S(IV)/Mn(VII) process while the impact mechanism was significantly altered by chloride. Additionally, the study observed a synergistic inhibition of DOM and chloride on the degradation of pollutants that are highly reactive towards Cl 2 •– and ClO•. [Display omitted] • Cl− altered the treatment efficiency of pollutants by the S(IV)/Mn(VII) process. • Cl− changed the distribution of reactive species in the S(IV)/Mn(VII) process. • Cl− retarded HSO3 − consumption, resulting in the decrease of RMnS concentration. • The impact mechanism of DOM on S(IV)/Mn(VII) process was markedly changed by Cl−. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A dual responsive ratiometric fluorescent probe for N 2 H 4 and HSO 3 − was developed. • Different color changes based on different sensing mechanisms for N 2 H 4 and HSO 3 −. • It has high selectivity and low detection limit for N 2 H 4 and HSO 3 −. • Good recovery was achieved in industrial water for detecting N 2 H 4 and HSO 3 −. • It has good biocompatibility. Abstract Hydrazine and bisulfite are poisonous to the environment and human health, hence it is necessary to monitor hydrazine and bisulfite in the environment and living cells. In this study, we reported a smart fluorescent probe (CMCA) for discriminative detection of hydrazine and bisulfite. The single fluorescent probe can respond to hydrazine and bisulfite with two different sets of colorimetric and ratiometric fluorescence signals together with high selectivity, fast response and low detection limit. The discriminative sensing behaviors of the probe for hydrazine and bisulfite were ascribed to different reaction mechanisms, which were confirmed by 1H NMR and HR-MS spectra. The probe has been successfully used to discriminatively determine hydrazine and bisulfite in industrial wastewater with good recoveries. Furthermore, the probe was employed to visualize hydrazine and bisulfite in live cells from different fluorescence channels with good performance. Therefore, this probe has great potential applications for discriminative detection of hydrazine and bisulfite in the environment and living cells. [ABSTRACT FROM AUTHOR]

A new fluorescent probe tetrahydro[5]helicene-malononitrile derivative was designed and synthesized for selective detection of bisulfite. This fluorescent probe exhibites high response speed and selectivity toward HSO 3 − in PBS solution over other coexisting species accompanied by a distinct fluorescence color change from yellow to blue, which can be visually identified. The probe shows excellent sensitivity to HSO 3 − and the detection limit is as low as 0.27 μM. Once reacted with HSO 3 − , the signal-to-background ratio of fluorescence intensity can reach a 45-folds enhancement and the quantum yield dramatically increases from 1.9% to 52.3%. The response mechanism proved to be a nucleophilic addition reaction of probe with HSO 3 − , which was confirmed by 1 H NMR, Mass titration and theory calculation. Additionally, the preliminary cell imaging experiments demonstrated that the probe could be used for intracellular bisulfite detection. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescent probe was designed and synthesized for detection of bisulfite, via pyrene as an electron donor (D) and 4, 5-dibromothiophene as an electron acceptor (A). It had good selectivity, sensitivity and short response time. The fluorescence intensity ratio at 420 nm and 530 nm (I 420 /I 530 ) displayed a good linear relationship with the concentration of HSO 3 − in the range of 0–35 μM, and the detection limit was 0.77 μM. The possible recognition mechanism of probe and HSO 3 − was illustrated by NMR, HRMS and computational analysis. Notably, the probe was successfully applied for imaging HSO 3 − in A549 cells, Caenorhabditis elegans and zebrafish, which indicated that this probe had great potential for HSO 3 − detection in vivo. [ABSTRACT FROM AUTHOR]

Abstract A spinel-type Co-Mn oxide was designed and synthesized through a two-step oxidation-precipitation method at modest temperatures. The Co-Mn oxide was applied as the catalyst in the presence of NaHSO 3 under visible light irradiation in order to establish the superiority of heterogeneous photo-chemical catalysis system. In the above system, the Co-Mn catalyst exhibited much better catalytic capability than that in either single photocatalysis or chemocatalysis system, implying that the Co-Mn catalyst could well combine photocatalysis and chemocatalysis to obtain the highest degradation efficiency of up to 94% within 40 min when using Orange II as the target pollutant. Recycling experiments results showed that the as-obtained catalyst has excellent stability and recyclability. Powder X-ray diffraction (XRD) analysis showed that the as-obtained Co-Mn catalyst had a cubic MnCo 2 O 4.5 spinel structure. Because of relatively low temperature (180 ℃) synthesis, the catalyst was formed with nanoparticles (25–65 nm) and high specific surface area as confirmed by SEM and BET analyses. XPS indicated the presence of both manganese and cobalt species that serve as reactive sites for the catalytic oxidation reactions. Rational degradation mechanisms responsible for superior catalytic activity and durability were proposed based on a series of experimental results. The active species such as Mn(III), holes and sulfate and hydroxyl radicals were proposed to be responsible for the outstanding degradation results. [ABSTRACT FROM AUTHOR]

A new benzo[ e ]indolium derivative 1 including pyridyl and thienyl groups was synthesized and characterized, which failed to response to Hg 2+ or Cu 2+ in aqueous system. However, it is interesting that when it reacted with bisulfite in HEPES buffer, the in situ generated ensemble as 1 -SO 3 H displayed dramatic absorption and fluorescence changes after adding Cu 2+ or Hg 2+ , which were contrary to the changes of 1 upon the addition of bisulfite ions. By contrast, the other two derivatives 2 and 3 showed the almost similar trends of spectral changes, which were short of ligating atoms N or S. The further investigation of 1 HNMR spectra changes of 1 showed that C−SO 3 H bond may be interrupted because the good binding capacity of Hg 2+ and Cu 2+ with O of C−SO 3 H weaken the binding force of C−SO 3 H, which resulted in the recovery of ethylene with benzo[ e ]indolium block. The DFT calculations results further confirmed it. [ABSTRACT FROM AUTHOR]

A new cycloruthenated 2-(2-thienyl)pyridine complex ( 1 ) with a benzo[ e ]indolium block was successfully synthesized and characterized, which has good water-solubility and displays a maximum absorption band centered at 730 nm (ε = 6.3 × 10 3  M −1  cm −1 ) in water. Moreover, its absorption edge can extend to 1000 nm. When either HSO 3 – or SO 3 2– ions were added to the buffer solutions of 1 , obvious color changes from dark-red to purplish-red were observed. However, it is noticeable that the addition of HSO 3 – ions resulted in the solution color of this complex changing from dark-red to colorless other than purplish-red. The different solution color changes displayed that 1 can be used as an optical chemo-sensor to distinguish HSO 3 – from SO 3 2– in pure water. [ABSTRACT FROM AUTHOR]

Organic contaminants can be oxidized rapidly in permanganate/bisulfite (PM/BS) process due to generation of Mn(III) aq . However, the influence of O 2 and its role in contaminants degradation in PM/BS process are poorly understood. Thus, the influence of O 2 concentration on phenol removal was quantified and isotopic oxygen tracers ( 18 O-labeled water and 18 O 2 ) were employed to further unravel the mechanisms of PM/BS process. The introduction of O 2 to PM/BS process appreciably improved phenol oxidation. Under oxic conditions the oxidation products of bisulfite included SO 4 2− and HSO 5 − while SO 4 2− was the single stable oxidation product under anaerobic conditions. The oxygen isotope labeling experiments confirmed that HSO 5 − originated from the oxidation of SO 3 − by O 2 to SO 5 − and the following reduction of SO 5 − by HSO 3 − . Incorporation of oxygen isotope from H 2 18 O to MnO 2 due to the disproportionation of Mn(III) aq was observed, which verified the generation of Mn(III) aq in PM/BS process. The critical influence of O 2 on PM/BS process was mainly associated with rapid oxidation of SO 3 − by O 2 to SO 5 − , which otherwise competed with target contaminants for Mn(III) aq . Oxygen from H 2 O and/or O 2 can also be incorporated in the degradation products of organics in PM/BS process. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of sulfite at a platinum electrode was investigated, in which changing the pH of supporting electrolytes caused qualitative changes in the oxidation behavior. In an acidic environment, oscillations in current were found to occur; however, only transient behavior was observed without the incorporation of an external resistor. Electrochemical impedance spectroscopic measurements indicate that the system possesses a region of negative differential resistance (NDR) at acidic conditions. To gain insights into the influence of pH, electrochemical oxidation of bisulfite was also studied, in which NDR was found, suggesting that changes in the dominant species induced by pH is responsible for the observed phenomena. Perturbation experiments illustrate the presence of bistability under galvanostatic conditions, lending support that the observed instabilities belong to the N-NDR class of electrochemical oscillators. Mass spectroscopic analysis and precipitation with barium ion suggest that SO 4 2− is a major product of the electro-oxidation of sulfite. [ABSTRACT FROM AUTHOR]

Bisulfite (HSO 3 − ) and sulfite (SO 3 2− ) compounds play key roles in numerous geochemical and biochemical processes extending from the atmosphere to the subseafloor biosphere. Despite decades of spectroscopic investigations, the molecular composition of HSO 3 − in solution remains uncertain and, thus, the role of bisulfite in (bio)chemical and isotope fractionation processes is unclear. We report new experimental estimates for the bisulfite isomer quotient ( Q i  = [(HO)SO 2 − ]/[(HS)O 3 − ]; [] = concentration) as a function of temperature from the interpretation of Raman spectra collected from aqueous NaHSO 3 solutions contained in fused silica capsules. In pure NaHSO 3 solutions (1Na + :1HSO 3 − , stoichiometric) over [NaHSO 3 ] = 0.2–0.4 m (moles/kg H 2 O), the following relationship is obtained: ln ( Q i ) = 878.59 ( ± 32.98 ) T - 1.9642 ( ± 0.1081 ) , where T = 278–358 K (5–85 °C) (based on 50 determinations; additional significant figures are provided to avoid rounding errors). This relationship suggests that the minor isomer, (HS)O 3 − , may comprise 23–38% (±3%) of the mole fraction of HSO 3 − over 5–85 °C, respectively, which is higher in relative abundance than has generally been understood previously. We additionally provide estimates for Q i in NaHSO 3 solutions containing a total ionic strength of µ  = 1.0 m (0.2 m NaHSO 3  + 0.8 m NaCl) and different pH (3.3–4.5), but do not appear to resolve any significant differences in Q i as a function of these additional variables. These new values of Q i are employed to re-assess the bulk sulfur isotope fractionations among bisulfite and other S(IV) compounds as a function of temperature, which appear to be highly dependent on the amount of (HS)O 3 − present. Our new constraints on the bisulfite isomer quotient may allow for a detailed assessment of the molecular composition and isotope mass balance of S(IV) solutions containing HSO 3 − , and may be useful in the further investigation of the mechanisms and isotope fractionations associated with a number of processes that involve bisulfite compounds. These may include the intracellular enzymatic transformations of sulfite and bisulfite compounds that occur as part of dissimilatory sulfate reduction, which is a major and geologically important form of anaerobic respiration. [ABSTRACT FROM AUTHOR]

A novel and powerful chemiluminescence (CL) system was developed based on the promoting effect of graphene quantum dots (GQDs)/bisulfite on rhodamine B (RB)-H 2 O 2 CL reaction. GQDs were synthesized by a simple, green and affordable approach and characterized using their distinctive absorption and emission patterns. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) transmission and transmission electron microscopy (TEM) analysis were implemented for complementary studies on the structural and morphological characteristics of GQDs. The simultaneous enhancing effect of the synthesized GQDs and bisulfite on the CL emission of RB-H 2 O 2 reaction provided a more strong and efficient CL system. The mechanism of CL emission was described. Furthermore, HCHO as a well-known pollutant, could selectively diminish the developed CL system. This effect was linearly proportional to HCHO concentration which turned the introduced CL system to a susceptible chemosensor for HCHO. Under the optimized operational condition, the linear changing of CL response was obtained in HCHO concentration ranges of 0.02–5 μg L −1 and 5–11 μg L −1 , with limit of detection (LOD) and quantification (LOQ) of 6 ng L −1 and 20 ng L −1 , respectively. Ultimately, presented CL chemosensor was served as an accurate tool for determination of formaldehyde concentration in water and wastewater samples. [ABSTRACT FROM AUTHOR]

• A lysosome-targeting probe has been developed based on pyrrole-tricyanofuran. • The probe shows AIE behavior in almost pure aqueous media. • The probe can detect HSO 3 − and viscosity on fluorescence and UV−Vis spectra. • The probe can image lysosomal HSO 3 − and viscosity in cells and zebrafish. A novel AIE active bifunctional probe for detecting bisulfite (HSO 3 −) and viscosity synchronously was developed based on pyrrole-tricyanofuran skeleton. This probe exhibited aggregation-induced emission behavior in almost pure aqueous media, and responded to HSO 3 − with a "turn-off" signal and viscosity changes with a "turn-on" signal in semi-aqueous solutions, respectively. The response mechanism of the probe associated with HSO 3 −-involving C C breakage was demonstrated via ESI-MS, 1H NMR analysis, and density functional theory calculations. Furthermore, the probe has been applied to imaging endogenous HSO 3 − and viscosity changes in the lysosomes of C6 cells and zebrafish. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The surface of Y-CDs was linked with Coum to afford Coum-CDs as a nanoprobe for HSO 3 −. • The Coum-CDs displayed a ratiometric response to HSO 3 − with a detection limit of 15 nM. • The nanoprobe exhibited higher sensitivity and outstanding specificity toward HSO 3 −. • The Coum-CDs were applied to ratiometric monitor HSO 3 − in live cells and food samples. As an important food additive, extensive intake of bisulfite (HSO 3 −) often leads to serious related diseases. However, the reliability and accuracy of HSO 3 − detection remains an outstanding challenge because the majority of previously reported sensors for HSO 3 − have been evaluated by the single-channel signal output. Herein, we constructed a ratiometric fluorescent nanoprobe, Coum-CDs , by covalently coupling the coumarin dye (Coum) onto the surface of yellow emissive carbon dots (Y-CDs) via amide bonds. The Coum-CDs themselves showed peculiar dual fluorescence emission at 480 and 565 nm under single-wavelength excitation. However, upon treatment with HSO 3 −, the π-conjugation structure of Coum was destroyed due to the selectively nucleophilic reaction between the C-4 atom of Coum and HSO 3 −, which shut off the pathway of fluorescence resonance energy transfer from Coum to Y-CDs. As a result, the fluorescence emission of Coum-CDs at 565 nm decreased significantly, accompanied by a slight change in fluorescence intensity at 480 nm, allowing the ratiometric detection of HSO 3 −. In addition, the nanoprobe Coum-CDs displays a very low detection limit of 15 nM and excellent selectivity without interference from other relevant analytes, especially reactive sulfur-containing species. Importantly, preliminary experiments showed that the Coum-CDs have been successfully applied to ratiometric monitoring of exogenous and endogenous HSO 3 − in living cells, as well as the quantitative measurement of HSO 3 − in sugar and wine. [ABSTRACT FROM AUTHOR]

In view of the important physiological role of HSO 3 − and H 2 O 2 , it is of great significance to develop fluorescent probes to detect HSO 3 − and H 2 O 2 in aqueous medium. We herein report a new fluorescent probe (E)-3-(2-(4-(1,2,2-triphenylvinyl)styryl)benzo [d]thiazol-3-ium-3-yl)propane-1-sulfonate (TPE-y) possessing benzothiazolium salt based on tetraphenylethene (TPE) moiety with aggregation-induced emission (AIE) characteristics. TPE-y can sequentially recognize HSO 3 − and H 2 O 2 through colorimetric and fluorescence dual-channel response in HEPES (pH = 7.4, 1% DMSO) buffer solution, and exhibits high sensitivity and selectivity, a large Stokes shift (189 nm), as well as a wide applicable pH range. The detection limits of TPE-y and TPE-y-HSO 3 for HSO 3 − and H 2 O 2 are 3.52 μM and 0.15 μM, respectively. The recognition mechanism is verified by 1H NMR and HRMS methods. Furthermore, TPE-y can detect HSO 3 − in sugar samples, and can image exogenous HSO 3 − and H 2 O 2 in living MCF-7 cells. TPE-y can relay detect HSO 3 − and H 2 O 2 , which is of great significance to maintain the redox balance in organisms. [Display omitted] • A long wavelength emissive AIE-based fluorescent probe TPE-y has been developed. • TPE-y displays sequential recognition to HSO 3 − and H 2 O 2 with colorimetric and fluorescent dual responses. • TPE-y can alternately recognize HSO 3 −/H 2 O 2 in a high water content media. • TPE-y can be applied to detect HSO 3 − in food samples and cell imaging. [ABSTRACT FROM AUTHOR]

A newly designed cyclometalated iridium complex Ir(mepi)(ppy) 2 (2, Hppy = 2-phenylpyridine, Hmepi = 3,3-dimethyl-1-ethyl-2-(4-(pyridin-2-yl)styryl)indolium iodide ( 1 )) was successfully synthesized for the rapid detection of HSO 3 − and CN − . For complex 2 , it is interesting that the selective 1,4-addition reaction with HSO 3 − in aerated DMSO/PBS buffer can be visualized by intense turn-on green emission. However, the 1,2-addition reaction with CN − resulted in an emission color change from colorless to orange-yellow. Furthermore, the limits of detection for HSO 3 − and CN − were calculated as low as 0.049 and 0.15 μM, respectively. The results indicate that the two anions can be detected selectively and separately by naked-eyes in neutral aqueous system. As the typical interfering anion for detecting HSO 3 − , HS − led to the almost similar emission change that was caused by HSO 3 − . As a result, the reaction between 2 and HS − could be assigned as 1,4-addition rather than 1,2-addition reaction, which was further confirmed by the 1 H NMR spectra changes of the ligand with these representative anions (HSO 3 − , HS − and CN − ). [ABSTRACT FROM AUTHOR]

Very recently, it has been reported that bisulfite can activate permanganate to enhance the oxidation of selected organic contaminates at acid and neutral pH, where aquo and hydroxo Mn(III) formed via the fast reaction of permanganate with bisulfite is proposed to be responsible. In this work, to gain further insight into the role of bisulfite, we investigated the degradation of an emerging endocrine disruptor bisphenol S (BPS) by the permanganate/bisulfite system. We found that permanganate showed very sluggish reactivity toward BPS, while the permanganate/bisulfite system rapidly oxidized BPS at pH 4–7 with rates (∼2.8–85.2 s −1 ) that were 6–7 orders of magnitude faster than those for permanganate alone (∼10 −6 s −1 ). Both rate and extent of BPS loss in the permanganate/bisulfite system maximized at the [bisulfite]:[permanganate] ratio of 5:1–10:1, appreciably higher than the stoichiometric ratio of 2:1. Similarly, thiosulfate and hydrosulfite also showed activating effects, where the loss of BPS exhibited dependency on the [thiosulfate]:[permanganate] or [hydrosulfite]:[permanganate] ratio as well. Comparatively, arsenite showed negligible activating effect, while the combination of arsenite and bisulfite resulted in appreciable degradation of BPS by permanganate even though arsenite outcompeted bisulfite for permanganate. In addition, it was found that several model organic ligands appreciably inhibited the degradation of BPS in the permanganate/bisulfite system while Fe(III) showed negligible effect. These results were rationalized by the fact that reduced sulfur inorganics acted as complexing agents to stabilize Mn(III), and the formation of reactive Mn(III)-sulfur complexes responsible for BPS degradation was at near diffusion-controlled rate (∼10 9 M −1 s −1 ) and thus not a rate-limiting step in the permanganate/bisulfite process. [ABSTRACT FROM AUTHOR]

Bisulfite, in the form of sodium bisulfite or metabisulfite, is used commercially as a food preservative. Bisulfite is used in the laboratory as a single-stranded DNA mutagen in epigenomic analyses of DNA methylation. Recently it has also been used on whole yeast cells to induce mutations in exposed single-stranded regions in vivo . To understand the effects of bisulfite on live cells we conducted a genome-wide screen for bisulfite sensitive mutants in yeast. Screening the deletion mutant array, and collections of essential gene mutants we define a genetic network of bisulfite sensitive mutants. Validation of screen hits revealed hyper-sensitivity of transcription and RNA processing mutants, rather than DNA repair pathways and follow-up analyses support a role in perturbation of RNA transactions. We propose a model in which bisulfite-modified nucleotides may interfere with transcription or RNA metabolism when used in vivo . [ABSTRACT FROM AUTHOR]

Reaction products of bisulfite and caftaric acid were found in wines containing sulfites as a preservative. Acidic compounds were separated from wine and analyzed by HPLC combined with DAD and QTOF mass spectrometer. HPLC chromatograms of the expected [M−H] − ion and UV absorption revealed the presence of five possible reaction products ( a – e ). These compounds were isolated then characterized by NMR and confirmed to be the reaction products as follows; 5-sulfo-( E )-caftaric acid ( a ), 2-sulfo-( Z )-caftaric acid ( b ), 2-sulfo-( E )-caftaric acid ( c ), ( E )-caftaric acid-4- O -sulfate ( d ) and ( E )-caftaric acid-3- O -sulfate ( e ). UV spectra and high resolution product ion spectra of the five compounds also supported their identity. The reaction products were confirmed to be commonly present in commercial wines across four vintages and two varieties. Their concentration was found to be as much as that of 2- S -glutathionyl caftaric acid, suggesting that bisulfite consistently competes as a nucleophile with glutathione for the o -quinone of caftaric acid. [ABSTRACT FROM AUTHOR]

A long-lived iridium(III) complex probe Ir_1 for bisulfite detection has been synthesized. The iridium(III) complex probe Ir_1 , containing double aldehyde groups in the N^N donor ligand, can react with bisulfite to form an adduct with enhanced luminescence. The interaction of probe Ir_1 with bisulfite was investigated through NMR and emission titration experiments. Upon the addition of bisulfite, probe Ir_1 displayed more than a 4-fold luminescence enhancement, and a detection limit of 0.35 μM was recorded. Probe Ir_1 shows a large Stokes shift (280 nm) and a long-lived luminescence which allows it to be distinguished from autofluorescent media through time-resolved emission spectroscopy (TRES). Finally, the applications of probe Ir_1 to the detection of bisulfite in living cells and zebrafish were described. [ABSTRACT FROM AUTHOR]