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Here, we report the reactivity of copper(I) clusters toward sulfide ions; these sulfide copper(I) clusters have attracted much attention due to their relevance to biologically active centers and their fascinating structural and photophysical properties. Treatment of the CuI3RhIII2 pentanuclear complex, [Cu3{Rh(aet)3}2]3+ (aet=2‐aminoethanethiolate), in which a {CuI3}3+ cluster moiety is bound by two fac‐[Rh(aet)3] metalloligands, with NaSH in water produced the CuI6RhIII4 decanuclear complex, [Cu6S{Rh(aet)3}4]4+, accompanied by the dimerization of [Cu3{Rh(aet)3}2]3+ and the incorporation of a sulfide ion at the center. While similar treatment using the analogous CuI3IrIII2 complex with fac‐[Ir(aet)3] metalloligands, [Cu3{Ir(aet)3}2]3+, produced the isostructural CuI6IrIII4 decanuclear complex, [Cu6S{Ir(aet)3}4]4+, the use of the CuI3RhIII2 complex with fac‐[Rh(apt)3] metalloligands, [Cu3{Rh(apt)3}2]3+ (apt=3‐aminopropanethiolate), resulted in the removal of one of the three CuI atoms from {CuI3}3+ to afford the CuI2RhIII2 tetranuclear complex, [Cu2{Rh(apt)3}2]2+. [ABSTRACT FROM AUTHOR]

A ratiometric-based fluorescence emission system was proposed for the determination of sulfide. It consists of blue emissive graphene quantum dots (GQDs) and self-assembled thiolate-protected gold nanoclusters driven by aluminum ion (Al3+@GSH-AuNCs). The two types of fluorophores are combined to form a ratiometric emission probe. The orange emission of Al3+ @GSH-AuNCs at 624 nm was quenched in the presence of sulfide ion owing to the strong affinity between sulfide and Au(I), while the blue GQDs fluorescence at 470 nm remained unaffected. Interestingly, the Al3+@GSH-AuNCs and GQDs were excited under the same excitation wavelength (335 nm). The response ratios (F470/F624) are linearly proportional to the sulfide concentration within the linear range of 0.02–200 µM under the optimal settings, with a limit of detection (S/N = 3) of 0.0064 µM. The proposed emission probe was applied to detect sulfide ions in tap water and wastewater specimens, with recoveries ranging from 95.3% to 103.3% and RSD% ranging from 2.3% to 3.4%, supporting the proposed method's accuracy. [ABSTRACT FROM AUTHOR]

[Display omitted] • A PEC sensor was proposed based on the precipitation dissolution equilibrium between AgI and S2−. • The photocurrent polarity was reversed after the formation of Ag 2 S on AgI/AuNP FTO. • The proposed PEC sensor showed high sensitivity and selectivity for S2− detection. Sulfides are widely used as industrial raw materials, but they also cause serious water pollution and pose a high risk to human health. Consequently, sensitive and selective methods for detecting sulfide ion (S2−) in water are required. In this work, a photoelectrochemical (PEC) sensor was proposed based on the precipitation-dissolution equilibrium between silver iodide (AgI) and S2− on a gold nanoparticle (AuNP)-modified fluorine-doped tin oxide (FTO) electrode. The sensor was characterized by scanning electron microscopy, X-ray diffraction, and UV–Vis spectroscopy and applied to detect S2− by measuring the photocurrent under Xe lamp irradiation. On the formation of Ag 2 S, the UV–Vis absorption spectrum of the electrode was red shifted and the absorbance increased significantly. Further, the photocurrent polarity was reversed as a result of the formation of Ag 2 S on the surface of AgI/AuNP FTO. Overall, the sensor showed high sensitivity and selectivity for S2− detection, and the detection was linear at 0.2–5.0 and 5.0–50.0 μmol/L with a limit of detection of 0.08 μmol/L. Crucially for practical applications, the sensor was reproducible and showed good recovery and accuracy in real samples. In summary, the proposed sensor owns advantages in simple fabrication, high sensitivity, selectivity, stability, and low cost, and has good application prospects in the environmental monitoring of S2−. [ABSTRACT FROM AUTHOR]

In this paper, a highly sensitive method for sulfur ion (S 2- ) detection was developed based on a four-color fluorescence probe constructed from copper-containing metal-organic framework (CuBDC) and four dye-labeled single-strand DNA (ssDNA). In the absence of S 2- , dye-labeled ssDNA can be adsorbed on the surface of CuBDC, and the dyes are close to copper ion on the CuBDC surface, their fluorescence is quenched by copper ion, and their fluorescence signals are weak. In the presence of S 2- in the system, S 2- reacts with copper ion in CuBDC to form CuS, which has a more stable structure than complex CuBDC, resulting in the decomposition of CuBDC. In this case, dye-labeled ssDNA are detached from the CuBDC surface and dissolved in the solution, and the fluorescence of the dyes is restored. Under the optimized conditions, there is a good linear relationship between the total fluorescence intensity of four dyes and the concentration of S 2- in the range of 2 × 10 -9 to 5 × 10 -8  mol/L; the detection limit is 2.2 × 10 -10  mol/L. The method has a good selectivity and accuracy, and it can be applied to the analysis and detection of S 2- in actual water samples., (© 2024 John Wiley & Sons Ltd.)

The rheology of a partially hydrolyzed polyacrylamide (HPAM) solution plays an important role in its oil recovery during polymer flooding. However, multiple factors in brine, such as sulfide ions, cause a dramatic loss in the viscosity and oil recovery. To better understand the sulfide-induced viscosity loss and the consequent flow mechanisms in pore networks, the morphology of polymer solutions with and without sulfide ion was observed by scanning electron microscopy; and the variations of the pore scale flow fields were demonstrated by a microscopic visualization seepage experiment combined with Micro-PIV (Microscale Particle Image Velocimetry). The results showed that, with the presence of sulfide ion, the microstructure of the polymer changed from a uniform three-dimensional network structure to loose and uneven floccules, which resulted in viscosity loss (over 70% with 5-mg/L sulfide ion). Moreover, higher concentrations of sulfide ions (5 mg/L and 10 mg/L) resulted in earlier shear thinning characteristics than those with lower sulfide concentrations. Due to viscosity loss, the average flow velocity in the main stream of the microscopic seepage experiment increased more significantly than that without sulfide. However, the viscosity loss alone cannot independently explain the severe viscous fingering during the subsequent post-water flooding, which was about five times greater than that of the primary water flooding in terms of the velocity ratio between the mainstream and margin. A further pore-scale flow field analysis exhibited an eccentric and a bimodal velocity distribution in the throat along the radial and axial directions, respectively. The former distribution indicated that the adsorbed polymer on the pore wall was broken through by hydraulic shear due to the collapsed structure caused by sulfide ion. The latter suggested that another sulfide-induced impact was an earlier-occurring non-Newtonian characteristic with a low shear rate. Therefore, instead of viscosity loss, elastic loss is the dominant mechanism affecting the characteristics of the aggregate flow field under the action of sulfide. Microscopic flooding combined with Micro-PIV is a feasible and essential method to reveal pore scale flow mechanisms. [ABSTRACT FROM AUTHOR]

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Sulfide ions (S2−) that are widely distributed in biological and industrial fields are extremely toxic and pose great harms to both ecological environment and human health. However, fluorescent sensors toward S2− ions commonly use S2−-recovered fluorescence of fluorophore that is first quenched mainly by metal ions. Fluorescent probe which enables direct, selective, and sensitive detection of S2− ion is highly desirable. Herein, we demonstrate one-step preparation of fluorescent ionic liquid–graphene quantum dots (IL-GQDs) nanocomposite, which can act as a fluorescent probe for direct and sensitive detection of S2− ion. The IL-GQDs nanocomposite is easily synthesized via facile molecular fusion of carbon precursor and in situ surface modification of GQDs by IL under hydrothermal condition. The as-prepared IL-GQDs nanocomposite has uniform and ultrasmall size, high crystallinity, and bright green fluorescence (absolute photoluminescence quantum yield of 18.2%). S2− ions can strongly and selectively quench the fluorescence of IL-GQDs because of the anion exchange ability of IL. With IL-GQDs nanocomposite being fluorescent probe, direct and sensitive detection of S2− is realized with a linear detection range of 100nM–10μM and 10μM–0.2mM (limit of detection or LOD of 23nM). Detection of S2− ions in environmental river water is also achieved.

The rheology of a partially hydrolyzed polyacrylamide (HPAM) solution plays an important role in its oil recovery during polymer flooding. However, multiple factors in brine, such as sulfide ions, cause a dramatic loss in the viscosity and oil recovery. To better understand the sulfide-induced viscosity loss and the consequent flow mechanisms in pore networks, the morphology of polymer solutions with and without sulfide ion was observed by scanning electron microscopy; and the variations of the pore scale flow fields were demonstrated by a microscopic visualization seepage experiment combined with Micro-PIV (Microscale Particle Image Velocimetry). The results showed that, with the presence of sulfide ion, the microstructure of the polymer changed from a uniform three-dimensional network structure to loose and uneven floccules, which resulted in viscosity loss (over 70% with 5-mg/L sulfide ion). Moreover, higher concentrations of sulfide ions (5 mg/L and 10 mg/L) resulted in earlier shear thinning characteristics than those with lower sulfide concentrations. Due to viscosity loss, the average flow velocity in the main stream of the microscopic seepage experiment increased more significantly than that without sulfide. However, the viscosity loss alone cannot independently explain the severe viscous fingering during the subsequent post-water flooding, which was about five times greater than that of the primary water flooding in terms of the velocity ratio between the mainstream and margin. A further pore-scale flow field analysis exhibited an eccentric and a bimodal velocity distribution in the throat along the radial and axial directions, respectively. The former distribution indicated that the adsorbed polymer on the pore wall was broken through by hydraulic shear due to the collapsed structure caused by sulfide ion. The latter suggested that another sulfide-induced impact was an earlier-occurring non-Newtonian characteristic with a low shear rate. Therefore, instead of viscosity loss, elastic loss is the dominant mechanism affecting the characteristics of the aggregate flow field under the action of sulfide. Microscopic flooding combined with Micro-PIV is a feasible and essential method to reveal pore scale flow mechanisms.

A novel multifunctional fluorescent peptide sensor based on pentapeptide dansyl‐Gly‐His‐Gly‐Gly‐Trp‐COOH (D‐P5) was designed and synthesized efficiently using Fmoc solid‐phase peptide synthesis (SPPS). This fluorescent peptide sensor shows selective and sensitive responses to Hg2+ and Cu2+ among 17 metal ions and six anions studied in N‐2‐hydroxyethylpiperazine‐N‐2‐ethane sulfonic acid (HEPES) buffer solution. The peptide probe differentiates Hg2+ and Cu2+ ions by a 'turn‐on' response to Hg2+ and a 'turn‐off' response to Cu2+. Upon addition of Hg2+ or Cu2+ ions, the sensor displayed an apparent color change that was visible under an ultraviolet lamp to the naked eye. The limits of detection (LOD) of DP‐5 were 25.0 nM for Hg2+ and 85.0 nM for Cu2+; the detection limits for Cu2+ were much lower than the drinking water maximum contaminant levels set out by the United States Environmental Protection Agency (USEPA). It is noteworthy that both D‐P5‐Hg and D‐P5‐Cu systems were also used to detect S2− successfully based on the formation of ternary complexes. The LODs of D‐P5‐Hg and D‐P5‐Cu systems for S2− were 217.0 nM and 380.0 nM, respectively. Furthermore, the binding stoichiometry, binding affinity and pH sensitivity of the probe for Hg2+ and Cu2+ were investigated. This study gives new possibilities for using a short fluorescent peptide sensor for multifunctional detection, especially for anions. [ABSTRACT FROM AUTHOR]

Highlights • The silk fibroin protected copper nanoclusters have been successfully demonstrated. • The Cu nanoclusters possessed unique aggregation/assembly induced emission enhancement characteristics in the present of S2−. • The S2− can induced the Cu nanoclusters of ca. 2.8 nm assembled to large nanoparticles of uniform rod-like with the size (47 ± 2) × (15 ± 2) nm. • The sensors exhibit a stable response for S2− in the range of 5 μM–110 μM. The LOD is 0.286 μM. Abstract Herein, we observed that the simple one-pot green method synthesized fluorescent silk fibroin (SF) protected copper nanoclusters (CuNCs) possessing unique aggregation/assembly induced emission enhance (AIEE) characteristics with the assistance of sulfide ion in aqueous solution. The interaction of CuNCs with S2− was further investigated by fluorescence spectroscopy, UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It demonstrated that the S2− can induced the ultrasmall Cu nanoclusters of ca. 2.8 nm orderly assembled to large nanoparticles of uniform rod-like with the size (47 ± 2) × (15 ± 2) nm by transmission electron microscopy (TEM). And the fluorescence intensity of the dispersed CuNCs was increased with the increase of absolute quantum yield from 1.6% to 4.9%. More importantly, the assembly large Cu nanoparticles are also monodispersed in size and morphology, which provides a distinctive advantage for analytical applications. Based on this, SF@CuNCs can be developed into a practical nanosensor for "turn-on" luminescence detection for S2− with a highly sensitive and selectivity. The linear response with the S2− concentrations range from 5.0 μM to 110.0 μM and detection limit was 0.286 μM. We demonstrated this assembled nanostructure as a powerful analytical platform for S2− detection. [ABSTRACT FROM AUTHOR]

Abstract Viscosity of polymer solution is one of the key factors which, in some case, notably influence its application effect. However, it has been found that the viscosity drops significantly with sulfide ion. To better understand this phenomenon, the rheological behavior, dynamic light scattering (DLS), and 1H NMR analysis were conducted. The results show that sulfide ion significantly reduced the viscosity of HPAM solution and this reduction was further enhanced under low pH and high O 2 content and, more specifically, could not be recovered by dialysis. The polymeric network structure of HPAM formed in water was apparently destroyed and the hydrodynamic radius was reduced by sulfide ion. Furthermore, 1H NMR spectra indicated that the chemical environment of some protons in the methyne group connected to amide group in HPAM was modified by sulfide ion. The interaction between sulfide ion and the amide groups in side chain intra-/inter-molecule of HPAM reduces the hydrodynamic radius and destroys the three dimensional network structure and consequently decreases the viscosity of HPAM solution. These results are helpful for investigating the mechanisms of HPAM-sulfide interaction and optimizing the usage of HPAM for enhanced oil recovery in oil reservoirs with sulfide ions produced by sulfate reducing bacteria. Highlights • Sulfide ions significantly reduce the viscosity of HPAM solution even at very low concentrations. • The viscosity reduction caused by sulfide is enhanced under low pH and high O 2 content and unrecoverable by dialysis. • The sulfide-amide interaction destroys the network of HPAM in solution and consequently decrease the viscosity. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract The interaction among the biologically synthesized silver nanoparticles (AgNPs) and industrially useful antibiotic kanamycin or environmentally hazardous sulfide ions led to the development of a possible colorimetric sensor for the selective detection of kanamycin and sulfide ions. In this study, a facile green protocol toward the synthesis of silver nanoparticles (AgNPs) was established while Epigallocatechin gallate (EGCG) was used as reducing and stabilizing agents, for the first time. The as-synthesized nanoparticles were characterized by UV–visible spectroscopy, high resolution transmission electron microscopy (HR-TEM) and dynamic light scattering (DLS) techniques. Detection of kanamycin and sulfide ions was established based on the SPR technique. The yellow color of the AgNPs solution turned to reddish pink in the presence of kanamycin, accompanying the decrease in intensity of SPR band. In contrast, AgNPs solution turned to colorless upon the addition of sulfide ions. The sensitivity and selectivity of AgNPs toward other interference antibiotics/anions were studied. Moreover, the effect of the concentration of kanamycin and sulfide ions in the nanoparticle solution was investigated and the LOD (limit of detection) for kanamycin and sulfide ions were found to be 0.96 μM and 1.62 μM, respectively. The results indicate that the proposed technique is very efficient for the colorimetric detection of kanamycin and sulfide ions. Highlights • EGCG is explored toward synthesis of stable silver nanoparticle. • Simple and cost effective method is reported for colorimetric detection of kanamycin. • Process for rapid colorimetric detection of hazardous sulfide ions is established. • Practicability of kanamycin detection is validated for milk sample. [ABSTRACT FROM AUTHOR]

[Display omitted] • A BODIPY chemosensor with 2,6-subsititution is designed for S2– detection. • Both absorption and fluorescence of the probe change with dosage of S2–. • The probe exhibits high selectivity and sensitivity with a short response time. • Change in intramolecular charge transfer is the sensing mechanism. • The probe shows low cytotoxicity and suits for S2– detection at cellular level. BODIPY derivatives have often been employed as fluorescent sensors to probe toxic ions in environment and living systems, such as sulfide ion (S2−). Whilst many structure modifications have been exploited on groups at the 3, 5, 8-positions, there are quite few examples on tailoring the 2,6-substituents for chemosensor investigations. Herein, we design and synthesize a 2,6-substituted BODIPY molecule, LM-BDP , to use as a fluorescent probe for detecting S2− in aqueous media. The electronic and crystal structures of the probe are studied by density functional theory (DFT) calculations and single-crystal X-ray diffraction analysis. Spectroscopy investigations are performed in a variety of conditions, showing that LM-BDP exhibits a noticeable color change from pink to dark red and a fluorescence shift from yellow to pink channel with decreased intensity upon addition of S2−. The selectivity and sensitivity measurements show that LM-BDP can only response to S2− with a detection limit of 0.29 μM in less than 100 s. The remarkable contrast in fluorescence images in test-stripe and RAW 264.7 cell experiments indicates that the probe is a proper candidate for the application in detecting exogenous S2−. [ABSTRACT FROM AUTHOR]

A novel Hg 2+ ion fluorescent sensor 1 has been synthesized based on amide group, sensor 1 showed a highly sensitive and selective response towards Hg 2+ over other metal ions by reversibly forming a [ 1 -Hg 2+ ] complex in 100% aqueous solution. The fluorescence detection limits was 0.41 nM. The Job's plots, the MS analysis and 1 H NMR titration experiments implied that there was only the formation of a 1 /Hg 2+ complex with 1:1 stoichiometry. Moreover, S 2− ion can remove Hg 2+ from the complex and restore the spectral signal of 1 . This research may enrich the field of multi-functional chemosensors in natural products. [ABSTRACT FROM AUTHOR]

In this paper, Bio-MOF-1 is prepared as reported and then Eu 3+ is introduced into it via cation exchange method. A FAM-labeled ssDNA is chosen to fabricate with the obtained Eu 3+ @Bio-MOF-1. A luminescent hybrid material is assembled, which can exhibit the fluorescence of Eu 3+ and FAM simultaneously by adjusting the ratio of FAM-ssDNA and Eu 3+ @Bio-MOF-1. The sample is then used for the detecting of metal ions, results shows which has good selectively for Cu 2+ (LOD = 0.14 μM, 0–250 μM). The introduction of Cu 2+ can quench the fluorescence of FAM while the luminescent intensity of Eu 3+ enhancing. After the detection of Cu 2+ , the Cu 2+ involved hybrid system can then be further employed for the detection of S 2− (LOD = 1.3 μM, 0–50 μM). Low concentration of S 2− can make the luminescent intensity of Eu 3+ decrease gradually while high concentration of S 2− can further recover the luminescent of FAM, which is quenched by Cu 2+ . [ABSTRACT FROM AUTHOR]

We demonstrate an advance in the fabrication of circular dichroism (CD) sensors for detection of Cd 2 + and S 2 − based on chiral CdS quantum dots (QDs) generated by a facile in-situ reaction. The chiral quantum dots are generated in solutions composed of Cd 2 + , S 2 − , cysteamine (CA) and L -penicillamine ( L -PA), with the number of the generated particles limited by either the Cd 2 + or S 2 − concentration. We show that the magnitude of the CD signal produced by the QDs is linearly related to the initial concentration of Cd 2 + and S 2 − , with excellent selectivity over other ions. Our sensor functions over concentration ranges of 65–200 μM and 7–125 μM with detection limits of 59.7 and 1.6 μM for Cd 2 + and S 2 − , respectively. The sensor is applied in real water samples with results comparing favorably with those obtained from ICP-OES (for Cd 2 + ) and HPLC (for S 2 − ). [ABSTRACT FROM AUTHOR]

As a common environmental pollutant, the sulfide anion (S 2− ) is toxic to the human body. We report here the simple preparation of a selective fluorogenic glycoprobe–metal complex for the rapid analysis of S 2− in full aqueous solution and real water samples. The probe was synthesized by “clicking” a dipropargyl naphthalimide dye with a water-soluble azido β- d -galactoside. Fluorescence spectroscopic analyses showed that the probe had an on–off response to Cu 2+ , forming a fluorogenic probe–Cu 2+ complex. The subsequent addition of S 2− selectively recovered the fluorescence of the complex over other anions tested, probably because of the high-affinity association between Cu 2+ and S 2− . The complex showed a good linear range and a nanomolar limit of detection with S 2− in full aqueous solution, and has also proven to be suitable for accurate recovery of spiked S 2− in real water samples. [ABSTRACT FROM AUTHOR]

• A quinolimide-based reversible sensor QPC for Cu2+ and S2− was developed. • QPC and its Cu2+ complex had the high specificity to detect Cu2+ and S2−. • QPC possessed high quantum yield, short response time, and low cytotoxicity. • The INHIBIT logic gate was simulated by the addition of Cu2+ and S2−. • QPC had been applied to detect Cu2+ and S2− in water samples and living cells. A quinolimide-based reversible fluorescent sensor QPC with carboxamidoquinoline as the receptor was prepared for the relay recognition of Cu2+ and S2−. QPC displayed the high selectivity and anti-interference ability to Cu2+ through the 1:1 binding mode. Subsequently, the selectively sensing S2− with the QPC Cu2+ complex gave a remarkable recovery of the emission. The LODs of QPC and its Cu2+ complex for Cu2+ and S2− were calculated to be 47.8 nM and 0.178 µM, respectively. Moreover, QPC and its Cu2+ complex had the satisfactory recoveries 93.5–105.8% for Cu2+ and 97.7–104.0% for S2− in water samples, and exhibited low cytotoxicity, which enabled them to image Cu2+ and S2− in yeast cells. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A ratiometric fluorescent gold@copper nanocluster of PVP/MBT-Au@CuNCs was prepared at 20 °C without cumbersome operation. • PVP/MBT-Au@CuNCs was applied to investigate the quality of Tremella and Radix Codonopsis with S2− pollution. • PVP/MBT-Au@CuNCs could recognize S2− in living cells. • The visual detection of S2− was realized with a dual-emissive ratiometric paper strip. • The established method is facile, eco-friendly, sensitive and efficient. Herein, a novel fluorometric-sensor with dual-emission system was constructed on the basis of polyvinylpyrrolidone (PVP) and 2-mercaptobenzothiazole (MBT) co-functionalized gold/copper nanoclusters (PVP/MBT-Au@CuNCs) by a facile and eco-friendly one-pot approach. The sensor exhibited ratiometric fluorescence emission (F 590 nm /F 422 nm) for visual and selective detection of S2− with a sensitive detection limit of 11.9 nM. Besides, fluorescence quenched sensing of S2− was chalked up by a quickly selectivity monitoring time of 30 s, owing to the strongly binding of Cu 2 S and Au 2 S by hard-soft-acid-base theory and the destruction of the aggregated structure of PVP/MBT-Au@CuNCs. Furthermore, the platform also provided the portable analysis for visual detection of S2− by capturing the change in fluorescence color with a single dual-emissive ratiometric paper strip. It is worth mentioning that the fluorescent gold-copper nanoclusters showed excellent application activities in the selective detection of S2− in Radix Codonopsis or Tremella samples and recognition of S2− in HeLa cells or macrophages by confocal microscopy fluorescent imaging. Overall, the sensing system paved a new avenue for effectively developing a convenient ratiometric fluorescent sensor platform for evaluating the safety of food with S2− pollution in environment and biological system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interaction of sulfide ion with edge and side-wall functionalized single wall carbon nanotubes is studied. • Mullikan and NBO charge analyses reveal transfer of charge from sulfide ion to SWCNTs. • UV–Vis–NIR spectral bands and simulated vibrational frequencies for functionalized SWCNTs have been studied. • Sidewall functionalized COOH+NH 2 -SWCNT has a greater sensing ability towards sulfide ion over the pristine SWCNT. Density functional theory (DFT) and Time Dependent Density functional theory (TD-DFT) calculations were performed to study the interaction of sulfide ion with pristine and edge/sidewall covalently functionalized single wall carbon nanotube (SWCNT, OH+NH 2 -SWCNT and COOH+NH 2 -SWCNT). NBO and Mulliken charge transfer between sulfide ion and pristine, edge/sidewall functionalized SWCNT (OH+NH 2 -SWCNT and COOH+NH 2 -SWCNT) was analyzed and a greater effect of charge transfer from analyte (sulfide ion) to SWCNT was calculated for sidewall functionalized carbon nanotube (COOH+NH 2 -SWCNT-S2-). Further, the electronic properties like ionization potential (IPs), electron affinities (EAs), and frontier molecular orbitals analysis were computed. Upon interaction appreciable decrease in energy gap is observed in all studied systems, however, the least energy gap is obtained in case of sidewall functionalized COOH+NH 2 -SWCNT-S2-. The simulated vibrational frequencies of both pristine and functionalized SWCNT interacting with sulfide ion were in good correlations with the reported literature. Similarly, the UV–Vis–NIR spectral bands for SWCNT-S2-, OH+NH 2 -SWCNT-S2- and COOH+NH 2 -SWCNT-S2- have been analyzed at TD-DFT-ωB97XD/6-31G (d,p). DFT study has revealed that the sidewall functionalized COOH+NH 2 -SWCNT has a greater sensing ability towards sulfide ion over the pristine SWCNT. [ABSTRACT FROM AUTHOR]

In this work, we have presented a novel strategy to utilize as-synthesized yeast extract-stabilized Cu nanoclusters (Cu NCs) for sensitive and selective detection of S 2− . The fluorescence intensity of Cu NCs was enhanced significantly in the presence of both Na 2 S 2 O 8 and S 2− . By virtue of this specific response, a Cu NC-based fluorescent turn-on sensor was developed, which allows the detection of S 2− in the range of 0.02–0.8 μM with a detection limit of 10 nM. The enhancing mechanism was also discussed based on fluorescence decay, transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies, indicating that S 2− enhanced the Cu NCs emission mainly through sulfide-induced aggregation of Cu NCs. Furthermore, we demonstrated the usability of the present approach for the detection of S 2− in water samples, which illustrates its great potential for the environmental monitoring and water quality inspection fields. [ABSTRACT FROM AUTHOR]

A new chromogenic and fluorogenic probe for the discriminative signaling of sulfide and azide ions using a nitrobenzoxadiazole (NBD)-dansyl dyad 3 has been investigated. Probe 3 showed prominent colorimetric and fluorescence signaling behavior toward sulfide and azide ions in aqueous tetrahydrofuran (THF). Anion selectivity was controlled by the water content in THF. In a water rich system (H 2 O/THF = 99:1, v/v), probe 3 reacted mainly with sulfide ions, owing to the sulfide-selective cleavage of the NBD-OSO 2 Ar bond, to yield the pink-colored NBD-SH and fluorescent dansyl acid. However, in water deficient conditions (H 2 O/THF = 10:90, v/v), probe 3 exhibited both azide- and sulfide-selective reactions, due to the cleavage of the NBD-OSO 2 Ar bond, to yield either NBD-N 3 (for azide ions) or NBD-SH (for sulfide ions), and dansyl acid. Azide ions can be discriminatively signaled by selective excitation at the NBD-N 3 without interference from the sulfide signaling products. This selective signaling behavior is not affected by other anions that might be present in the environmental samples. To test the practical use of this probe, we created a test strip that could be used to detect sulfide and azide ions. [ABSTRACT FROM AUTHOR]

Immensely sensitive, accurate, and simple on-site colorimetric sensor has been developed for the quantitative detection of the sulfide ion in human blood plasma. The colorimetric sensor consists of lead-ion-modified silica-gel powders placed in a glass tube. The powder color changes upon reaction with sulfide ions in blood plasma. It is capable of easily detecting toxic sulfide ion by using a glass tube with an inner diameter of 3 mm. By employing the type of colorimetric sensor to a blood sample, it is possible to detect the sulfide ion with a concentration limit of 0.1 ppm and excellent reproducibility, thus making it superior to conventional analysis methods that need multiple preparation processes and various sophisticated instruments. Since the sensor reported here is insensitive to environmental conditions such as temperature or humidity, and is featured by simplicity, fast response, high sensitivity, and easily understandable results based on absolute affirmative/negative response, it is expected to be effectively used for on-site applications such as detecting poisonous ions in blood samples. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxidation of sulfide ion on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNTs) and a copper (II) complex was investigated. The Cu(II) complex was used due to the reversibility of the Cu(II)/Cu(III) redox couple. The MWCNTs are evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on Cu(II) complex adsorbed on MWCNTs immobilized on the surface of GCE. The modified GCE was applied to the selective amperometric detection of sulfide at a potential of 0.47 V ( vs. Ag/AgCl) at pH 8.0. The calibration graph was linear in the concentration range of 5 µM-400 µM; while the limit of detection was 1.2 µM, the sensitivity was 34 nA µM. The interference effects of SO, SO, SO, SO, Cysteine, and Cystein were negligible at the concentration ratios more than 40 times. The modified electrode is more stable with time and more easily restorable than unmodified electrode surface. Also, modified electrode permits detection of sulfide ion by its oxidation at lower anodic potentials. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A highly specific and sensitive chromatographic method for the determination of sulfide ions was developed. The procedure is based on the sensitive and specific reaction of sulfide ions with 4-[p-(N,Ndimethylamino) phenyl]-2,6-diphenylpyrylium cations. The product of the reaction is a thiopyrylium derivative which can be quantitatively determined. Separations were performed on cellulose thinlayer chromatography (TLC) plates with a mixture of phosphoric buffer (pH 3.0), propan-2-ol, and acetonitrile (4:4:0.5, v/v) as the mobile phase. The thiopyrylium derivative was visible in the form of blue spots against a colorless background, which were converted into a chromatogram using TLSee software. Linearity was obtained in the range of 40-500 pmol per spot. The limits of detection and quantification were 10 pmol per spot and 33 pmol per spot, respectively. The proposed method was successfully used for the detection and determination of sulfide ions in water samples from the Busko Zdrój health resort. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, green curcumin nanoparticles (CURNs) are introduced for colorimetric sensing of sulfide using micelle mediated cloud point extraction for the first time. CURNs are transferred into non-ionic surfactant phase and show strong surface plasmon absorption intensity. The extraction of CURNs to the surfactant rich phase is suppressed in the presence of Cu2+ but upon addition of sulfide, the extraction of CURNs to the surfactant rich phase is increased again. This increase in the absorbance of surfactant rich phase is related to the sulfide concentration and was used as an analytical signal for the sensing of sulfide. The effect of chemical variables such as pH of the sample solution, concentration of Cu2+, electrolyte and CURNs on the cloud point extraction was studied. Under optimum conditions, the change in absorption intensity was linearly proportional to the concentration of sulfide in the range of 0.5–200.0ngmL−1 with a detection limit of 0.4ngmL−1. The relative standard deviations for 10 replicate measurements of 20ngmL−1 and 175ngmL−1 of sulfide were 4.1% and 1.4% respectively. The method was successfully applied to the determination of sulfide in different water samples. [Copyright &y& Elsevier]

The interactions of S 2− and HS − ions with gold, silver, and copper were studied by density functional theory using the cluster model of the metal surface. The geometrical and energy characteristics of the interactions of these ions with the surface metal atoms were evaluated. The S 2− ions form stronger chemical bonds with the surface metal atoms than HS − ions. A significant charge transfer from anion to metal occurs during the adsorption. The adsorbability increased in the series Ag < Cu < Au for both anions. The HS − ion showed greater ability to be transferred to the surface during the electrochemical adsorption due to the strong hydration of the S 2− ion. In alkaline media, however, the dissociation of the adsorbed HS − leads to its conversion to S 2−. [ABSTRACT FROM AUTHOR]

Abstract: This work reports a spectrofluorimetric method for selective and sensitive determination of sulfide ion in aqueous solution. The ultra-small zinc sulfide quantum dots (QDs) doped with manganese (ZnS:Mn) were synthesized by using a simple and fast procedure based on the co-precipitation of nanoparticles in aqueous solution in the presence of 2-mercaptoethanol, as capping agent. The nanoparticles have exhibited two strong fluorescent emissions at about 424 and 594nm. Luminescent surface-capped ZnS:Mn QDs, with particle size below 5nm, have been applied for determination of sulfide anions in water samples. Under the optimum conditions, the fluorescence intensity of ZnS:Mn QDs is linearly proportional to the sulfide ion concentration in the range 1.2×10−6 to 2.6×10−5 molL−1 with a detection limit as 3.3×10−7 molL−1. The relative standard deviation for five replicate measurements (for 8.0×10−6 molL−1 of S2−) was obtained to be 2.6%. It was founded that the interference of the other anions was negligible on the quantitive determination of sulfide ion. [Copyright &y& Elsevier]

Abstract: Photocatalytic hydrogen production was investigated over ZnS1−x−0.5y O x (OH) y –ZnO using sulfide ion (Na2S–Na2SO3) as an electron donor from NaCl saltwater. NaCl can affect markedly the activity for photocatalytic hydrogen production, depending on NaCl concentration. When NaCl concentration is lower, the activity is lower than that in pure water, whereas when NaCl concentration is higher, the activity is higher than that in pure water. NaCl decreases not only the surface charge of ZnS1−x−0.5y O x (OH) y –ZnO but also the surface hydration. When ZnS1−x−0.5y O x (OH) y –ZnO was impregnated with the electron donor (Na2S–Na2SO3), ZnO was transformed partly into ZnS. The impregnated ZnS1−x−0.5y O x (OH) y –ZnO exhibits higher activity than the non-impregnated one. The possible mechanisms were discussed. [Copyright &y& Elsevier]

Simple and sensitive TLC-densitometry (method 1) and HPTLC with TLSee software (method 2) have been used for analysis of sulfide ions in water. For both methods, separations were performed on silica gel 60 with dichloromethane-methanol-diethyl ether-25% aqueous ammonia 8:1:1:0.2 (v/v) as mobile phase. Sulfide ions were detected using the 'methylene blue method' - production of methylene blue (MB) by oxidative coupling of sulfide with N,N-dimethyl-pphenylenediamine (DMPD) in the presence of iron(III) ions in acidic medium. In method 1 the spots were scanned at 660 nm. In method 2 spots were converted into chromatograms by use of TLSee software. Both methods were validated. Response for both was a linear function of concentration in the range 20-100 pmol per spot. The limits of detection and quantification were 10 pmol per spot (3.2 mg L-1) and 20 pmol per spot (6.4 mg L-1), respectively. [ABSTRACT FROM AUTHOR]

It is shown that the gold dissolution in thiocarbamide electrolytes containing sulfide ions in the pH range from 1 to 4 proceeds with a current efficiently of almost 100%, and a change in solution acidity has a weak effect on the process. The oxidation of thiocarbamide to formamidine disulfide proceeds at the potentials around 1.1 V and depends on the pH of solution. When the pH value is raised, the thiocarbamide oxidation potential shifts in the negative direction and approaches the potential of gold dissolution. It is found that, in the absence of catalytically active species, the gold dissolution rate in thiocarbamide solutions in the pH range from 6 to 10 is vary low. At these pH values, as well as in the acidic solutions, an addition of less than 10−4 M sulfide ions to thiocarbamide electrolyte accelerates the gold dissolution at the potentials about 0.6 V. It is shown that sulfide ions in the concentration above 10−4 M inhibit the process. At pH 11, the gold dissolution proceeds also with no special addition of sulfide ions. This is associated with the formation of sulfide ions as a result of accelerated decomposition of thiocarbamide and formamidine disulfide with increasing pH value. It is found that in the pH range from 12 to 13, the processes of gold dissolution and thiocarbamide oxidation are inhibited as a result of the formation of passive film on the electrode surface. Probably, the film consists of elemental sulfur. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode followed partial order kinetics (between current and mass transport control) in the absence and presence of chloride ion and of naphthenic acids, at sulfide concentrations typical of sour brines. The desired outcome was to promote the 2-electron oxidation of sulfide to elemental sulfide rather than the 8-electron oxidation to sulfate. Although elemental sulfur accumulated to some extent at low conversion of sulfide, sulfate ion became the principal product as the reaction progressed. At high conversion, the overall current efficiencies were typically higher than 50%, with material balance about 90%. However, this anode material was gradually poisoned by sulfide in long term use. [ABSTRACT FROM AUTHOR]

NiW systems are known as one of the best catalysts for various desulfurization processes. In this study, we examined catalytic properties of NiW electrodeposits, produced from two different electrolytes, towards sulfide ion oxidation in alkaline solution. Despite the big difference in morphology and structure of both materials, they exhibit almost the same catalytic activity for the examined reaction. A possible explanation of this experimental fact is that the overall reaction is controlled by the transport of oxygen through the catalyst samples. [ABSTRACT FROM AUTHOR]