Metal Anions Research Articles

Amino-functionalized 3D crosslinked Ti3C2Tx nanosheets for highly efficient UO22+ and ReO4− immobilization simultaneously from aqueous solutions

Construction of the multifunctional Ti3C2Tx for efficient extraction of radioactive metal cations and anions from radioactive waste simultaneously remained challenging. Decorating Ti3C2Tx into multifunctional materials with controllable and desired properties was an efficient strategy for eliminating UO22+ and ReO4−. In this work, a novel amino-functionalized 3D crosslinked Ti3C2Tx nanosheets (N-CTC) were designed by covalent bonding crosslinking method, followed by a facile hard template to prevent the delamination Ti3C2Tx nanosheets from stacking. Introducing amino functional groups and adjusting surface charge of N-CTC considerably enhances the removal of simultaneously UO22+ and ReO4− from aqueous solutions. Impressively, N-CTC exhibited the exceptional trapping capacities toward UO22+ (550.71 mg/g) and ReO4− (105.01 mg/g), which were significantly superior than that of the pristine Ti3C2Tx nanosheets. More importantly, N-CTC also possessed fast rapidly and recyclable UO22+/ReO4− extraction in different artificial water samples. The elimination mechanism was clearly visualized by spectral analysis, uncovering UO22+ removal was abided by chelation effect, whereas the ReO4− adsorption was determined by both inner-sphere complexation and electrostatic interaction. The present results illustrate an effective strategy to design functionalized 3D crosslinked Ti3C2Tx nanosheets with effectively extraction of radioactive metal cations and anions from wastewater.

Synthesis, Single Crystal X-ray Structure, Spectroscopy and Substitution Behavior of Niobium(V) Complexes Activated by Chloranilate as Bidentate Ligand

Chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, caH2) as a bidentate ligand for Nb(V) as a metal center is presented. The different coordination behavior of caH2 is well illustrated by a monomeric (Et4N)cis-[NbO(ca)2(H2O)OPPh3]·3H2O.THF (5) and a novel tetranuclear compound (Et4N)4[Nb4O4(ca)2(μ2-O)2Cl8]·2CH3CN (6) via self-assembly, respectively. These were obtained in >80% yields and characterized by IR, UV/Vis and NMR (1H, 13C{1H}, 31P{1H}) spectroscopy and single crystal X-ray diffraction, and they included a systematic assessment of the solid-state behavior. The anionic metal complexes showed different coordination modes at the Nb(V): [Nb4O4(ca)2(μ2-O)2Cl8]4− (6a; distorted octahedral) and cis-[NbO(ca)2(H2O)(OPPh3)]− (5a; D5h distorted pentagonal bipyramidal), respectively. The tetranuclear complex 6a is substitution inert, while cis-[NbO(ca)2(H2O)OPPh3]− (5a) allowed a systematic ligation kinetic evaluation. The substitution of the coordinated triphenylphosphine oxide by a range of pyridine-type entering nucleophiles, 4-N,N-dimethyl-aminopyridine (DMAP), pyridine (py), 4-methylpyridine (4Mepy), 3-chloropyridine (3Clpy) and 3-bromopyridine (3Brpy) in acetonitrile at 31.2 °C was carefully evaluated. The subtle interplay between the main group ligand systems and the hard, early transition metal Nb(V) complex (5a) was well illustrated. The entering monodentate ligands showed a 15-fold reactivity range increase in the order 3Brpy < 3Clpy < 4Mepy < py < DMAP in broad agreement with the Brønsted-donating ability of the nucleophiles. The activation parameters determined for the reaction of 5a with DMAP as the entering ligand yielded ΔH≠kf = 52 ± 1 kJ mol−1 and ΔS≠kf = −108 ± 3 J K−1 mol−1 for the enthalpy and entropy of activation, respectively, indicating an associative substitution mechanism. The study presents an important contribution to the structure/reactivity relationships in Nb(V) complexes stabilized by chloranilic acid as a bidentate ligand.

Analyte Detection: A Decade of Progress in the Development of Optical/Fluorescent Sensing Probes.

The development of selective and sensitive chemical sensors capable of detecting metal ions, anions, neutral species, explosives and hazardous substances, selectively and sensitively has attracted considerable interest of various research groups. The presence of such analytes within the permissible limits is often beneficial, but the excess amounts may lead to lethal effects to both the environment as well as the living organisms. Owing to the toxicity of the heavy metal ions, toxic anions and nitro-aromatics which are main constituents of explosives, the timely detection of these materials is most desirable to ensure safety and security of the mankind. In this personal account, we present several classes of molecular sensors that were specifically designed in our lab during the past decade for detecting several species in solutions, solid state as well as biological media. Modulation of the optical properties in response to the presence of guest species, led to selective and sensitive detection protocols, and was supported by the theoretical studies wherever possible. We have also extended the application of some of these probes for the on-site detection of analytes by developing the paper strips, glass slides and even the wool and cotton fabrics loaded with probes. One such development represents detection of palladium in human urine and blood samples collected from clinical samples. Additionally, the sensing events in some cases have successfully been reproduced in the live cancer cells. Based on the ease and cost-effective synthesis of the molecular probes, we hope that this account shall provide significant information to researchers in understanding the structure dependent sensing capabilities of the molecular probes.

One‐pot synthesis of POM‐CaO2@ZIF‐8 nanoparticles with self‐supply of H2O2 for electrically enhanced chemodynamic therapy

Chemodynamic therapy (CDT) is a highly effective clinical treatment strategy based on the Fenton or Fenton‐like responses. However, its efficacy has been greatly limited by the complex tumor microenvironment, TME, such as the low levels of H2O2 and the overexpression of the glutathione (GSH). Polyoxometalates (POMs) are compounds that consist of anionic transition metal oxide clusters, such as tungsten (W) and molybdenum (Mo), and notably, these compounds have excellent redox properties in biological systems that can be utilized therapeutically. Therefore, POM‐CaO2@ZIF‐8 nanoparticles (NPs) have been synthesized and used as a mediator to develop an electrically enhanced CDT strategy. It is hoped that the simultaneous modulation of endogenous (the H2O2 generated by CaO2 NPs and GSH depletion by POM) and exogenous (Electric, E) stimulation enhanced Fenton‐like responses will lead to better therapeutic results. Such a treatment strategy has shown excellent tumor cell killing effects in both in vitro and in vivo studies.

Luminol immobilized on the metal–organic framework: As an efficient and highly sensitive sensor for the detection of antibiotics in aqueous medium

In this research, an anionic metal–organic framework (MOF) with the general formula of [HDMA]2[Zn2(BDC)3(DMA)2]·6DMF (HDMA+: dimethylamonnium, BDC2−: 1,4‐benzenedicarboxilate, DMA: dimethylamine, and DMF: N,N′‐dimethylformamide), namely, TMU‐3, was synthesized by the solvothermal method and then modified with the chemiluminescent reagent of luminol via post‐synthetic modification. The Luminol@TMU‐3 was incorporated as an ideal sensor for the immediate detection of four kinds of antibiotics such as cephalexin, amoxicillin, ampicillin, and 6‐aminopenicillanic acid (6‐APA) in aqueous media. Based on the results, Luminol@TMU‐3 exhibits high throughput and high efficiency of luminescent intensity, and the limit of detection (LOD) of cephalexin (in the 0.001 to 1000 μM concentration range), amoxicillin (in the 0.05 to 100 μM concentration range), ampicillin (in the 0.05 to 100 μM concentration range), and 6‐APA (in the 0.001 to 500 μM concentration range) is estimated to be 0.00005, 0.0001, 0.00012, and 0.00003 μM, respectively. High sensitivity, high throughput, and high fidelity are some of the notable features of this unique diagnostic platform, which can act as a universal device in the quantitative and rapid recognition of a wide range of analytes.

Anion-Directed Synthesis of Core–Shell and Janus Hybrid Nanostructures

Hybrid nanoparticles show considerable promise with potential applications ranging across catalysis (including photocatalysis), energy conversion, and storage. A generalized synthetic procedure for hybrid nanoparticles is presented. The method offers the flexibility to drive the products toward different hybrid nanostructure morphologies merely via a change in the metal anion, under otherwise identical experimental conditions. Both Ag@CZTS (CZTS = Cu2ZnSnS4) core–shell nanoparticles and Ag2S-CZTS Janus nanoparticles, along with PbS and Au/AuAg hybrid analogues, are synthesized using this methodology, highlighting its versatility and translatability across different materials. The nucleation of the semiconductor is the critical determining step for the synthesis of a given hybrid product. Insight into the mechanism of growth for these two morphologies paves the way for the rational and generalized synthesis of hybrid nanoparticles.

A comparative study of selected vitex species for phenolics estimation along with their antioxidant and herbicidal activities

This study aims to quantitative, qualitative estimation of phenolics, antioxidant (DPPH free radical scavenging, nitric oxide radical scavenging, superoxide anion scavenging, reducing power and metal chelating activity), and herbicidal properties of methanol extract of Vitex species {(Vitex negundo L. collected from Haldwani (VNH), Bhimtal (VNB) and Salari (VNS); Vitex agnus-castus L. collected from Pantnagar (VACP); Vitex trifolia L. collected from Pantnagar (VTP)}, Kumaun region, Uttarakhand, India. Herbicidal activity of methanol extracts of Vitex species was evaluated against Raphanus sativus at various concentrations for 120 h. The results revealed that the phenolic content varies from species to species as well as their location. HPLC profiling of Vitex species was carried out to identify the presence of different phenolic acids viz: vanillic acid, ferulic acid, p-coumaric acid, etc. In methanol extracts of Vitex species. VTP showed the highest DPPH (IC50 = 6.84 μg/mL), nitric oxide (IC50 = 2.86 μg/mL) and superoxide radical scavenging (IC50 = 3.12 μg/mL) activity. The maximum reducing power was observed in VNH (RP50 = 28.22 μg/mL) and the highest ion chelating capacity in VNB (IC50 = 6.80 μg/mL). The effective herbicidal activity was shown by VNS, resulting in complete inhibition of seed germination. Based on the heatmap clustering selected species are divided into two clusters. The first cluster comprises VNB and VTP are there whereas in the second cluster there are two sub-clusters including VNS only in one sub-cluster and VNH and VACP in the second sub-cluster.

Anion detection employing synthetic chemosensors in aqueous media

Water is a vital component of our daily life. A variety of human-caused climate change as well as natural geochemical aging of soil and rocks leads to water pollution. Through water the pollutants can easily enter human and animal food network. These contaminants include heavy metals cations, anions, pesticides, cosmetics, polymers, dyes, and drugs. When consumed through the contaminated water these toxins can cause direct injury to human beings and animals even at concentrations slightly higher than the permissible limit. Thus, wastewater or contaminated water treatment is a major goal for scientists and policymakers these days. To remove the contaminants from water, first and foremost, the pollutants must be identified. As a result, many techniques are used and/or being developed to validate water adulteration, such as detection of pollutants using nanocomposites, supramolecular approaches, metal–organic frameworks, heteronuclear-organic frameworks, polymeric membranes, molecule-based optical chemosensors etc. This article focuses on the detection of particular anions (F–, CN–, PO43–, SO42–, NO2–, S2-, Cl-) in aqueous medium using synthetic optical chemosensors as well as computational research to validate the detection method of anion in the aqueous media.

Unveiling the role of counter-anions in amorphous transition metal-based oxygen evolution electrocatalysts

At the initial stage of the oxygen evolution reaction (OER) most electrocatalysts undergo structural and chemical surface reconstruction. While this reconstruction strongly influences their performance, it is frequently overlooked. Herein, we analyze the role of the oxidized anions, which is particularly neglected in most previous works. We introduce a range of different anionic groups (Cl-, CH3COO-, NO3-, SO42-) on the surface of an amorphous ZnCoxNiyOz catalyst by a facile proton etching and ion exchange method from a ZIF-8 self-sacrificial template. The structural and chemical properties of the obtained set of materials are thoroughly analysed and correlated with their electrocatalytic performance to study the effect of surface anionic groups, phase transition, metal leaching and defect generation on OER activity. Exploiting the control possibilities provided by the synthesis method here described and employing the uncovered property-performance correlations, the electrocatalyst is optimized. As a result, we produce ZnCo1.25Ni0.73Ox-SO4 catalysts with outstanding OER performances, including a low overpotential of 252 mV at 10 mA cm−2 with a small Tafel slope of 41.6 mV dec−1. Furthermore, this catalyst exhibits remarkable stability with negligible overpotential variation for 100 h. The excellent catalytic properties are rationalized using density functional theory calculations, showing that the surface-adsorbed anions, particularly SO42−, can stabilize the OOH* intermediate, thus enhancing the OER activity. This work offers new insight into the roles of metal leaching and surface-adsorbed anions in the OER progress and facilitates the rational design of highly-efficient electrocatalysts for OER.

Synthesis of anionic rare-earth metal salan complexes as catalysts for copolymerization of cyclohexene oxide with cyclic anhydrides

• New anionic rare-earth metal salan complexes [Et 3 NH][salanMCl 2 ]. • Promoting the ROCOPs without cocatalyst producing alternating polyesters. • Different substituents and central metals affect the catalytic activity. Several new rare-earth metal salan complexes of [Et 3 NH][salanMCl 2 ] were synthesized and evaluated as catalysts for copolymerization of cyclohexene oxide (CHO) with cyclic anhydrides. It was found that all of the complexes show moderate activities toward the copolymerizations without any cocatalysts, resulting in alternating polyesters with number-average molecular weight (M n ) of 1.7–2.2 kg/mol. Both the different substituents and central rare-earth metals of the catalysts affect the catalytic activity. Catalysts carrying bulkier substituents show lower activity. In general, [Et 3 NH][salanYCl 2 ] complexes show relatively high activity in comparison to their lutetium analogues bearing the same ligands.

Adsorptive removal of heavy metal anions from water by layered double hydroxide: A review.

High-valence heavy metals with high ecotoxicity are generally found in water in the form of anions, and this increases heavy metal pollution intensity and treatment difficulty. Recent studies have pointed to the potential efficiency of layered double hydroxides (LDHs) to meet this challenge. In this review, we retrospectively research the development of LDHs using a Java application called CiteSpace. We describe the unique layer structure, highly adjustable chemical properties, and diverse synthesis methods of LDHs, all of which decide the effective adsorption of heavy metal anions by LDHs. Subsequently, we focus on discussing the adsorption mechanism of LDHs on heavy metal anions, as well as the current state of research and future directions for microscopic interaction mechanisms. For practical applications, it is critical to improve the adsorption selectivity and stability. We then recommend solutions to improve the adsorption selectivity and stability after identifying the influencing mechanism. Finally, we provide our perspectives on the future development of LDHs adsorption of heavy metal anions.

A Comprehensive Review on Analytical Applications of Hydrazone Derivatives

This review covers a summary of analytical applications of hydrazone derivatives in a systematic manner (1961-2021), which will help researchers in the design and development of hydrazone derivatives as potential candidates in medicinal, pharmaceutical, catalytic, and analytical chemistry, especially in the separation, identification, and detection of several metal ions, anions, organic molecules, and water in various real and synthetic samples. In addition to these, hydrazone derivatives may be used as light emitting diodes, for synthesis of DSSC, nanoparticles and polymers, as corrosion inhibitors, as dyes, etc. This review does not include all papers in this field, but it does synthesize all significant works on the subject.

Research and Application Progress of Geopolymers in Adsorption: A Review.

Geopolymer is a porous inorganic material with a three-dimensional mesh structure, good mechanical properties, a simple preparation process (no sintering) and a low economic cost, and it is environmentally friendly. Geopolymer concrete has been widely used in the construction field, and many other studies have revealed that geopolymer will become one of the most promising inorganic materials with unique structure and properties. This paper provides a review of the development and current status of geopolymers and briefly explains the effects of material proportioning, experimental factors and activators on geopolymer performance. Because of the advantages of high specific surface area and high porosity, geopolymers could be used as adsorbent materials. This paper summarizes the research progresses of the adsorption of metal cations, anions, dyes, and gases by geopolymers, which emphasizes the geopolymer membranes in adsorption, and discusses the challenges and opportunities for the development of more efficient, sustainable and practical adsorption protocols.

Leaching and characterization studies of heavy metals in contaminated soil using sequenced reagents of oxalic acid, citric acid, and a copolymer of maleic and acrylic acid instead of ethylenediaminetetraacetic acid.

In this work, the removal performance of three environmentally friendly reagents, oxalic acid (OA), citric acid (CA), and a copolymer of maleic and acrylic acid (PMAA), on heavy metals in polluted soil was studied at the optimum conditions and compared their sequenced performance. The results showed that the consecutive washing with the individual acids significantly improved the removal percentage of heavy metals in the soil compared to that of EDTA (10.2%, 71.3%, 29.8%, 61.6%, and 52.4% removal for As, Cd, Cu, Pb, and Zn, respectively). The removal of As, Cd, Cu, Pb, and Zn in the sequence of CA-OA was 65.6%, 79%, 59.1%, 64.6%, and 63.5%, respectively. In addition, the organic acids had little influence on the soil physicochemical properties after washing with slight reductions of acidity (pH) and soil organic matter (SOM), which are the major determinants of the usability of washed soils for plant growth. The germination rate of Sorghum bicolor in CA-OA-washed soils reached over 70% on the 7th day. CA-OA-washed soils collectively stand out in using washed soils for plant growth with the following advantages: simultaneous removal of cationic and anionic metals, less harmful impact on soil properties, and successful support for the germination of crops. Based on the findings, we recommend the CA-OA sequence as the best alternative to EDTA with higher metal removal efficiency and germination success.

Synthesis and Fluorescence Studies of Diborene Coinage Metal Complexes.

Nine different coinage metal (Cu, Ag) π complexes of diborenes with various anionic diborene (aryl, heteroaryl) and metal substituents (Cl, Br, C6F5, C2SiMe3), stabilizing neutral donors (N-heterocyclic carbene = NHC, phosphine), configurations (cis/trans, acyclic/cyclic diborene), and charges (neutral, cationic) were synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallographic analyses. Their optical properties were investigated by UV-vis absorption and steady-state as well as time-resolved luminescence spectroscopy in solution and the solid state to gain insights into the excited-state behavior of this unusual class of photoactive compounds and to provide structure-property relationships. The structural and electronic modification of the (B═B)···M motif greatly influences not only the visible light absorption but also the photostability and quantum yields, which can reach high values of up to f = 0.42. The lifetimes are found in the nanosecond regime, providing estimated radiative rate constants over a wide range of kr = 1.3-14 × 107 s-1, indicative of fluorescence. Intersystem crossing (ISC) is sufficiently slow for prompt emission from the S1 state to be observed, while the spin-orbit coupling in the T1 state is too weak for phosphorescence to occur at room temperature. ISC can be accelerated, however, by modifying diborene ligand substitution and the coinage metal center, hinting at the potential for exploiting the properties of long-lived triplet excited states of metal diborene complexes in the future.

Anionic Porous Zn-Metalated Porphyrin Metal-Organic Framework with PtS Topology for Gas-Phase Photocatalytic CO2 Reduction.

Presented here are the synthesis and gas-phase photocatalytic CO2 reduction of an anionic porous Zn-metalated porphyrin metal-organic framework (MOF) induced by an ionic liquid. The desired CO2 affinity and deep conduction band position of the MOF catalyst provide strong kinetic and thermodynamic advantages for photocatalytic CO2 to CH4 conversion with high selectivity (∼70%) in H2O vapor.

Fluorinated Materials as Positive Electrodes for Li- and Na-Ion Batteries.

Fluorine is known to be a key element for various components of batteries since current electrolytes rely on Li-ion salts having fluorinated ions and electrode binders are mainly based on fluorinated polymers. Metal fluorides or mixed anion metal fluorides (mainly oxyfluorides) have also gained a substantial interest as active materials for the electrode redox reactions. In this review, metal fluorides for cathodes are considered; they are listed according to the dimensionality of the metal fluoride subnetwork. The synthesis conditions and the crystal structures are described; the electrochemical properties are briefly indicated, and the nature of the electron transport agent is noted. We stress the crucial importance of the elaboration processes to induce the presence of cation disorders, of anion substitutions (mainly F-/O2- or F-/OH-) or vacancies. Finally, we show that an accurate structural characterization is a key step to enable enhanced material performances to overcome several lasting roadblocks, namely the large irreversible capacity and poor energy efficiency that are frequently encountered.

Zn2+-enhanced Ru (II) photoluminescence directed by double-clamp structural ligand for selective Zn2+ sensing and live-cell imaging

A novel water-soluble, visible-light-excitable, fluorescence enhancement sensor (λex = 450 nm), [Ru (PYPZA-tBuDO3A) (bipy)2]2+, has been synthesized and characterized, which efficiently recognize Zn2+ ions without interference from other biologically relevant metal ions, anions, amino acids, small biomolecules or pharmaceutical molecules in phosphate buffered saline (PBS, pH = 7.0). The detection has high sensitivity (detection limit = 5.3533 × 10-9 mol/L) for Zn2+ ions owning to the formation of 1:1 binding with a large binding constant (K = 2.1586 × 105 M-1). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were performed to determine the mechanism for changes of photophysical properties illustrating fluorescence increase response to Zn2+ ions. The [Ru (PYPZA-tBuDO3A) (bipy)2]2+ also exhibits excellent membrane permeability and negligible cytotoxicity, and can be applied to sense intracellular Zn2+ in live human cells.

Fast responsive colorimetric and ratiometric fluorescence chemoprobe based on a 1,8–naphthalimide for nM recognition of Cu2+ and its application in real food and drinkable water samples

In this research, a novel 1,8–naphthalimide–based colorimetric and ratiometric fluorescence chemoprobe (NAPH) was realistically developed for the recognition of copper (II) (Cu2+) in different vegetables and drinkable water samples. The sensing studies of NAPH depicted a ratiometric ''turn–on'' fluorescent response from bright yellow to blue as well as a colorimetric response toward Cu2+ from yellow to colorless, and it was found to be unselective towards various metal ions, anions and amino acids. The fast response of NAPH to Cu2+ caused a wavelength shift from 550 nm to 454 nm, and hence NAPH was used to recognize Cu2+ with an ultralow detection limit (9.53 nM). To validate the spectral data of NAPH, the study was performed using important analytical parameters and statistical tests. The binding stoichiometry between NAPH and Cu2+ was computed as 1:1 by Job's plot method as well MALDI TOF MS. Besides, the binding constant between the NAPH and Cu2+ was found to be 6.84 × 103 M–1. In addition to sensing studies, density–functional theory (DFT) findings strongly confirmed spectral data, and the Smartphone sensing results demonstrated that NAPH could be utilized as a powerful tool for the monitoring of Cu2+ without the need for sophisticated equipment. A test paper application was also performed to achieve semi–quantitative detection and to produce test kits with excellent selectivity toward Cu2+ without interfering metal ions. Furthermore, the newly designed probe NAPH was not only successfully used to recognize Cu2+ in bottled drinking waters (93.93–103.97%) but also was employed for vegetables with satisfactory results (92.97–109.92%).

Yeast Inhibitive Assay for Anionic Heavy Metals: A review

One of the most common types of pollution that has a negative impact on the biotic community in aquatic habitats is heavy metal poisoning of the water. Both essential and non-essential heavy metals can be toxic to living things if their concentrations are too high for their bioavailability. Although the toxicity of heavy metals, and especially anionic metal ions, is better known than that of cationic metal ions, it is just as toxic, if not more so. The focus of this review is on the usefulness of eukaryotic organisms like yeast, Saccharomyces cerevisiae, for toxicity assessment because they can be easily maintained and developed in controlled circumstances, thereby avoiding variability issues that arise when employing more complex organisms. Recent research has shown that the majority of cellular MTT reduction occurs outside of the mitochondrial inner membrane, and that this reduction is dependent on NADH and NADPH but is resistant to respiratory chain inhibitors.