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The Schiff base chelating ligands; (E)-2-(3,3-dimethoxy-2-oxa-7,10-diaza-3-silaundec-10-en-11-yl)phenol (L1), (E)-N-(2-((pyridine-2ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L2) and (E)-N-(2-((thiophen-2-ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L3) were immobilized on Fe3O4 magnetic nanoparticles (MNPs) and utilized in the extraction of Cr(VI), Cd(II) and Pb(II) metal cations from aqueous solutions. The compounds synthesized, denoted as L1@ Fe3O4, L2@Fe3O4, and L3@Fe3O4, were characterized using FT-IR spectroscopy, TEM-SEM, VSM, and BET/BHJ techniques for analysis of functional groups, surface morphology, magnetic properties, and degree of porosity of the adsorbents, respectively. BET/BHJ technique confirmed the mesoporous nature of the compounds as their pore diameters ranged between 15 and 17 nm. The initial optimization conditions of pH, adsorbent dosage, initial metal concentration, and contact time on adsorption were studied using L1@ Fe3O4. The optimum efficiencies recorded were 68% and 46% for Cr(VI) and Cd(II), respectively, obtained at pH 3, and a metal concentration of 20 ppm while an efficiency of 99% was recorded for Pb(II) cations at pH 7 and a metal concentration of 100 ppm. Compounds L2@Fe3O4 and L3@ Fe3O4 were also used in the extraction of metal cations from aqueous solution and gave efficiencies of 22%, 56%, and 78% for L2@ Fe3O4 and 19%, 90%, and 59% using L3@ Fe3O4 for Cr(VI), Cd(II), and Pb(II), respectively. The maximum adsorption capacities of L1@ Fe3O4 for Cr(VI), Cd(II), and Pb(II) cations were obtained from the Langmuir isotherm as 32.84, 41.77, and 450.45 mg/g, respectively. The experimental data was analyzed using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. Both linear and non-linear forms of kinetic isotherms; Langmuir, Freundlich, Redlich-Peterson, and Temkin were utilized to investigate the nature of adsorption on L1@Fe3O4. The mechanistic studies deduced that the Langmuir isotherm and pseudo-second-order kinetic model better described the adsorption process both yielding high correlation coefficient values (R2 > 0.98). [ABSTRACT FROM AUTHOR]

The 203Pb and 212Pb lead radioisotopes are attracting growing interest as they can aid in the development of personalized, targeted radionuclide treatment for advanced and currently untreatable cancers. In the present study, the bonding interactions of Pb2+ with twelve macrocyclic ligands, having an octa and nona coordination, were assessed using Density Functional Theory (DFT) calculations. The molecular structures in an aqueous solution were computed utilizing the polarized continuum model. The preference for the twisted square antiprismatic (TSAP) structure was confirmed for ten out of the eleven cyclen-based complexes. The characteristics of the bonding were assessed using a Natural Energy Decomposition Analysis (NEDA). The analysis revealed a strong electrostatic character of the bonding in the complexes, with minor variations in electrical terms. The charge transfer (CT) had a comparable energetic contribution only in the case of neutral ligands, while in general, it showed notable variations regarding the various donor groups. Our data confirmed the general superiority of the carboxylate O and aromatic N donors. The combination of the selected efficient pendant arms pointed out the superiority of the acetate pendant arms and the lack of significant cooperation between the different pendant arms in the probed ligands. Altogether, the combination led only to a marginal enhancement in the total CTs in the complexes. [ABSTRACT FROM AUTHOR]

The synthesis, structural characterization, and catalytic application of two novel aluminum complexes, [κ3ENSe−{Ph2P(E)N−C6H4−SePh}AlMe2] [E=S (1) and Se (2)] supported by new pincer‐type phenylselenium‐phosphanamidinate chalcogenide ligands are described. The molecular structures of both complexes in their solid states reveal a distorted trigonal bipyramidal geometry around the Al(III) ion, involving monoanionic ligand {Ph2P(E)N−C6H4−SePh}− bonded to the AlMe2‐motif in a tridentate manner. Complex 1 was found to be an effective pre‐catalyst for the cyanosilyation of aldehydes and ketones with TMSCN under solvent‐free conditions. The reaction protocol is simple, efficient, and has a diverse substrate scope of aldehydes and ketones, showing superior functional group tolerance. The kinetic study revealed that ketone reduction proceeded with first‐order dependence on ketone concentrations, TMSCN, and catalyst 1. [ABSTRACT FROM AUTHOR]

The synthesis, reactivity, and complexation with Fe(0) precursor of a tight‐bite bis(N‐heterocyclic silylene) (bis(NHSi)) ligand 1 are reported. The reaction of 1 with p‐toluidine led to the activation of both N−H bonds across Si(II) atoms to afford a four‐membered heterocyclic cyclodisilazane 2, with hydride substituents attached to five‐coordinate Si atoms. A 1 : 2 reaction of 1 with Fe(CO)5 led to an intriguing dinuclear complex 3 featuring a five‐membered (N−Si−Fe−Fe−Si) ring with a Fe−Fe bond distance of 2.6892(13) Å. All compounds (1‐3) were thoroughly characterized by various spectroscopic methods and X‐ray diffraction studies conclusively established their molecular structures. DFT calculations were carried out to shed light on bonding and energetic aspects in 1–3. [ABSTRACT FROM AUTHOR]

Natural and anthropogenic chelating ligands play important roles in promoting mineral dissolution during water-rock interactions. To address the remaining issue of how chelating ligands participate in the dissolution of minerals, this study investigated the dissolution characteristics of seven types of silicate minerals in the presence of a chelating ligand, N,N-bis(carboxymethyl)-L-glutamic acid (GLDA), which is a glutamic acid derivative, through batch dissolution experiments. The results showed that the dissolution of all types of silicate minerals, i.e., olivine (nesosilicate), epidote (sorosilicate), tourmaline (cyclosilicate), enstatite (single-chain inosilicate), hornblende (double-chain inosilicate), biotite (phyllosilicate), and anorthite (tectosilicate), can be enhanced by up to two orders of magnitude at both pH 4 and 8. The chelating ligand particularly facilitated the dissolution of minerals with a higher Al content, such as tourmaline and anorthite. Furthermore, the presence of chelating ligands enhanced the leaching of not only metals but also Si from minerals, resulting in a more congruent characteristic of mineral dissolution. A possible mechanism is that the chelating ligand adsorbs onto the negatively charged the mineral surface, which attracts more H+ and polarizes Si-O and Mg-O bonds, thereby dissolving the minerals at a faster rate. These results have significant implications for understanding the dissolution of minerals in nature and for the application of chelating agents in geological and materials engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of novel ruthenium(ii) complexes with nitron-type N-heterocyclic carbene ligands containing chelating (N -arylcarbamoyl)methyl or carboxymethyl groups have been synthesized. Their evaluation as precatalysts in the hydrogenation of ketones has revealed that the complex containing three N -mesityl groups (one on the carbamoyl- methyl moiety and two on the triazole moiety) is the most efficient one. [ABSTRACT FROM AUTHOR]

A series of silica-based aerogels comprising novel bifunctional chelating ligands was prepared. To produce target aerogels, two aminosilanes, namely (3-aminopropyl)trimethoxysilane (APTMS) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), were acylated by natural amino acids ((S)-(+)-2-phenylglycine or L-phenylalanine), followed by gelation and supercritical drying (SCD). Lithium tetrachloropalladate was used as the metal ion source to prepare strong complexes of Pd2+ with amino acids covalently bonded to a silica matrix. Aerogels bearing chelate complexes retain the Pd2+ oxidation state after supercritical drying in CO2, but the Pd ion is reduced to Pd metal after SCD in isopropanol. Depending on the structure of amino complexes, Pd-containing aerogels showed catalytic activity and selectivity in the hydrogenation reactions of C=C, C≡C and C=O bonds. [ABSTRACT FROM AUTHOR]

In search for structural features that enable the control of the valence isomerization of the fluxional bullvalene, a bullvalene‐bis(harmane) conjugate is identified that acts as chelating ligand in complexes with metal ions. Spectrometric titrations show that this ligand forms 1 : 1 complexes with Ag+, Cu+, Cu2+, and Zn2+. Most importantly, detailed NMR‐spectroscopic analysis at different temperatures reveals that the complexation with Ag+ strongly affects the dynamic isomerization of the bullvalene unit of the ligand such that only one predominant valence isomer is formed, even at 5 °C. Detailed 1H‐NMR‐spectroscopic studies disclose an increased barrier (~11 kJ mol−1) of the Cope rearrangement. Furthermore, the addition of hexacyclene displaces the Ag+ from the complex, so that the valence isomerization is accelerated and an equilibrium with two predominant isomers is formed. In turn, repeated addition of Ag+ regains the complex with the restrained isomerization of the bullvalene unit. This method to control the valence isomerism by straightforward chemical stimuli may be used to simplify structural analysis at elevated temperatures, i. e. a feature not available so far with bullvalenes, and it may be employed as functional element in dynamic supramolecular assemblies. [ABSTRACT FROM AUTHOR]

In this study, we compared carbene and pyridine substituted ligands {3‐Me‐1‐[2‐(CH2CH2SPh)]‐C7H4N2} (L1) and {2‐[(2,6‐iPr2‐C6H3)N=CH]‐6‐(MeO)C5H3N}(L2) for synthesis of ionic C,S‐ and N,N‐coordinated Ru (II) complexes [(κ2‐L1)RuCl(η6‐p‐cymene)]+Cl− (1), [(κ2‐L1)RuI(η6‐p‐cymene)]+I− (2), and [(κ2‐L2)RuCl(η6‐p‐cymene)]+Cl− (3), respectively. Stannylene ligand [{2,6‐(Me2NCH2)2C6H3}SnCl] (L3), as heavy carbene analog, was also used in this study to prepare neutral Sn‐coordinated Ru (II) complex [(κ1‐L3)RuCl2(η6‐p‐cymene)] (4). Finally, reaction of SnCl2 with 1, 3, and 4 was also studied to yield [(κ2‐L1)RuCl(η6‐p‐cymene)]+[SnCl3]− (5), [(κ2‐L2)RuCl(η6‐p‐cymene)]+[SnCl3]− (6), and [(κ1‐L3)RuCl (SnCl3)(η6‐p‐cymene)] (7). The catalytic activity of 1–7 was tested on aerobic oxidation of benzylamine. The effect of different ligands L1–3 as well as the effect of the SnCl3− moiety is discussed. [ABSTRACT FROM AUTHOR]

Heavy metals' contamination of water resources is a global environmental issue due to their detrimental effects on human health. To safeguard humans and the environment, toxic heavy metals must be removed from contaminated water because they cannot be broken down. Diverse technologies are employed to reduce the levels of heavy metals in wastewater. However, these technologies suffer from being either costly or ineffective, particularly when the effluent has extremely low residual amounts. This review outlines the main accomplishments and promising future directions for solvent extraction as one of the potential methods of extracting heavy metals from water, utilizing literature reports. In addition to reviewing some of the commercial chelating reagents now in use, this article also discusses some of the obnoxious effects on human health that are associated with exposure to heavy metals. HIGHLIGHTS Water pollution by heavy metals is a global issue.; Some heavy metals are toxic to plants and human life.; Chelation extraction of heavy metals is a potential technology for remediation of heavy-metal polluted water.; Chelation extraction is potentially more efficient and selective.; With respect to green chemistry principles such as solvent-free technique, functionalization of mesoporous silica is a promising alternative.;

The mixture was quenched with H SB 2 sb O (20 mL) and CH SB 2 sb Cl SB 2 sb (100 mL) was added. The reaction mixture was then stirred for 12 h at rt, quenched with H SB 2 sb O (10 mL), and CH SB 2 sb Cl SB 2 sb (75 mL) was added. Keywords: phosphines; aryl chloride; chelating ligands EN phosphines aryl chloride chelating ligands 2737 2741 5 08/17/23 20230901 NES 230901 Graph Phosphines represent the most widely used ligand class in homogeneous catalysis. [Extracted from the article]

Semicarbazide (OC(NH2)(N2H3)) and thiosemicarbazide (SC(NH2)(N2H3)) are well-known for their coordination complex formation ability. They contain nonbonding electrons in the form of heteroatoms (N, O and S) and π-electrons in the form of >C=O and >C=S through they strongly coordinate with the metal atoms and ions. Because of their association with this property, the Semicarbazide (SC), thiosemicarbazide (TSC) and their derivatives are widely used for different applications. They serve as building blocks for synthesis of various industrially and biologically useful chemicals. The SC, TSC and they derivatives are also serve as strong aqueous phase corrosion inhibitors. In the present reports, the coordination ability and corrosion protection tendency of Semicarbazide (SC), thiosemicarbazide (TSC) and their derivatives is surveyed and described. These compounds are widely used as inhibitors for different metals and alloys. Through their electron rich sites they adsorb on the metal surface and build corrosion protective film. Their adsorption mostly followed the Langmuir adsorption isotherm. Through their adsorption they increase the value of charge transfer resistance and decrease the value of corrosion current density. Computational studies adopted in the literature indicate that SC, TSC and their derivatives adsorb flatly and spontaneously using charge transfer mechanism. [ABSTRACT FROM AUTHOR]

• PICA improved OPs removal in the Fe(III)/PI process at near-neutral pH conditions. • OPs structures affected their removal rates and the reactive species contribution. • OPs with larger E HOMO , smaller IP, and smaller ΔE had higher removal rate. • FeIV=O was identified based on the sulfoxide probe and 18O isotope-labeling tests. • Fe(III)-PICA/PI process has great long-term effectiveness in actual water matrixes. The application of Fe-catalyzed periodate (PI) processes is often limited by both the narrow applicable pH range and weak reaction between Fe(III) and oxidant. Here, the biodegradable picolinic acid (PICA) was used as one kind of chelating ligands (CLs) to enhance the removal of organic pollutants (OPs) at initial pH 3.0−8.0, which displayed superior properties than the other CLs in Fe(III)/PI process. The dominant reactive species produced in the Fe(III)-PICA/PI process turned out to be high-valent iron-oxo (FeIV=O) species and hydroxyl radical (•OH) by quenching, sulfoxide probe transformation, and 18O isotope-labeling tests. The relative contribution of FeIV=O and •OH was dependent on OPs ionization potential (IP) and energy gap (ΔE). The degradation of OPs was also directly associated with their structure, the apparent rate constants correlated well with the highest occupied molecular orbital energy (E HOMO), IP, and ΔE, and among them ΔE had a greater effect. Furthermore, Fe(III)-PICA complexes displayed excellent long-term effectiveness for OPs removal in actual water matrixes, along with the non-toxic conversion of PI, indicating a broad application perspective of Fe(III)-PICA/PI process. This study provides an efficient method to improve the performance of Fe(III)/PI process and reveals the mechanism and relationship between removal efficiency and pollutant structure. [Display omitted] [ABSTRACT FROM AUTHOR]

The exploration of phosphorus-nitrogen heterocycles derived from chelating N-donor ligands is an area of research that has lagged behind the development of similar heterocycles based on other main group elements, most notably boron. The fact that phosphorus and nitrogen are both group 15 elements and that their compounds are most commonly viewed as Lewis bases likely contributes to this observation. However, through judicious ligand design and creative use of phosphorus sources that render phosphorus as Lewis acidic and/or electron poor, a variety of heterocyclic architectures are possible. In this article, we highlight selected examples of phosphorus adducts of bidentate, tridentate, and tetradentate N-donor ligands that have shown utility as functional molecular materials, in small molecule activation and catalysis, and as therapeutics and diagnostics in chemical biology. Finally, we look forward to the future of this emerging area and provide commentary on the unique opportunities available to researchers working within the field of phosphorus-nitrogen heterocycle chemistry., (© 2025 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Carbon dots (CDs) have been widely applied in metal ion recognition and detection, which makes them promising in the fields of environmental monitoring and biomedical science. However, CDs usually contain multiple functional groups that have different affinities for metal ions, so the relationship between CDs and recognized metal ions is ambiguous, which limits the prediction of recognized metal ions. Herein, CDs with different chelating ligands were target synthesized via free radical polymerization in combination of hydrothermal carbonization technology, the precursors directional converted into CDs. The tailor-made CDs with ethylenediamine tetraacetic acid (EDTA, EfCDs) and hydroxyethylidene diphosphonic acid (HEDP, HfCDs) chelating ligands were synthesized with high synthetic yields of 86.7% and 72.5%, respectively. The coordination constant (K) and the number of chelation site (n) of EfCDs for Fe3+ were (3.92 ± 0.03) × 104 M−1 and 3.62 ± 0.18, while the values of K and n of HfCDs for Cu2+ were (5.95 ± 0.04) × 105 M−1 and 1. EfCDs and HfCDs can serve as fluorescence probes for specific recognition of Fe3+ and Cu2+, respectively. Based on the metal-chelating affinity of EDTA and HEDP for Fe3+ and Cu2+ (lgK EDTA-Fe = 25.1, lgK HEDP -Cu = 12.5), EfCDs and HfCDs were predicted to specifically recognize Fe3+ and Cu2+. We established the exponential type functions between fluorescence quenching degree (1-F/F 0) and coordination constant (lgK) of EDTA or HEDP to facilitate the prediction of specific recognition of metal ions. This study proposes a new strategy for heavy metal ions specific recognition using CDs with tailor-made chelating ligands. Carbon dots with different chelating ligands were target synthesized via free radical polymerization in combination of hydrothermal carbonization technology, in which precursors were directional converted into carbon dots. The chelate functionalized carbon dots modified with EDTA and HEDP can achieve specific recognition of Fe3+ and Cu2+ and enhanced magnetic resonance imaging. [Display omitted] • Target synthesis of CDs via free radical polymerization and carbonization process. • The coordination constant and chelation sites of functionalized CDs were calculated. • Established exponential type functions between lgK and (1-F/F 0). • Predicted and confirmed CDs with EDTA and HEDP specifically recognize Fe3+ and Cu2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • Up to 1,200 mg kg−1 REE extracted from commercial rock phosphate fertilizers. • REEs in fertilizers can be readily leached (>80 %) using 1.5 M HCl at 25 °C. • TODGA-associated organosilica sorbent recovered up to 90% of REEs at < 0 pH. • Resin-in-pulp separation system selectively separated REEs from other metals. Phosphate fertilizers are the main source for heavy metal and hazardous metal enrichment in agricultural soils, which can pose health risks to exposed organisms including humans. Recovery of valuable and potentially hazardous metals such as rare-earth elements (REEs) from phosphate fertilizers before land application could limit the total metal loading of fertilizer-applied agricultural fields while providing an alternate supply of metals in the form of a value-added REE concentrate. Laboratory experiments evaluated the potential to extract and separate REEs from three different types of rock phosphate fertilizer samples. Total REE concentrations measured with aqua regia microwave digestions ranged from 300 to 1,200 mg REE kg−1 rock. More than 80% of the total leached REEs were from 5 elements (La, Ce, Nd, Pr, and Y). Extremely fast extraction kinetics were observed in acid leaching experiments, with > 90% REE extraction within 15 min in 1.5 M HCl concentrations with a liquid–solid ratio of 20 mL g−1. Two methods of REE recovery from leachates were examined: (1) precipitation and (2) solid–liquid extraction with a new diglycolamide-associated sorbent media. A pH increase step (increasing the pH from ∼ pH 0 to pH 2.5 with NaOH) precipitated more than 95 % of the REE from the leachate and produced a concentrate powder suitable for further enrichment. Proof-of-concept experiments using a new TODGA-associated organosilica media with filtered leachate or in a resin-in-pulp system demonstrated that REEs can be selectively separated from non-REE ions. Economic analysis of the metal oxide equivalent value (MOEV) identified metal values in phosphate fertilizer as high as $60 per ton. These findings may help reduce REE inputs from phosphate fertilizers to agriculture while also providing for recovery of critical elements that are crucial for many important technologies. [ABSTRACT FROM AUTHOR]

N-acylhydrazones 2-(4-chlorophenyl)-N0 -(2-hydroxybenzylidene)acetohydrazide, N0 -(2-hydroxybenzylidene)-2-(4-methoxyphenyl)acetohydrazide, 2-(4-chlorophenyl)-N0 -(2,4-dihydroxybenzylidene)-acetohydrazide, and N0 -(2,4-dihydroxybenzylidene)-2-(4-methoxyphenyl)acetohydrazide were successfully synthesized by a multistep procedure. The obtained organic molecules were characterized by spectroscopic techniques (FT-IR, 1D and 2D NMR, UV-Vis) and mass spectrometry. The structure of 2-(4-chlorophenyl)-N0 -(2-hydroxybenzylidene)acetohydrazide was also confirmed by X-ray diffraction. Ab initio computational simulations of the ligand spectra were in good agreement with experimental data and validated the hypothesis about the existence of a conformational mixture of each ligand in solution. Finally, the complexation potential of the synthesized ligands to Cu2+ was assessed by continuous variation experiments and FT-IR spectroscopy.

Abstract Background 64Cu is one of the few radioisotopes that can be used for both imaging and therapy, enabling theranostics with identical chemical composition. Development of stable chelators is essential to harness the potential of this isotope, challenged by the presence of endogenous copper chelators. Pyridyl type chelators show good coordination ability with copper, prompting the present study of a series of chelates DOTA-xPy (x = 1–4) that sequentially substitute carboxyl moieties with pyridyl moieties on a DOTA backbone. Results We found that the presence of pyridyl groups significantly increases 64Cu labeling conversion yield, with DOTA-2Py, −3Py and -4Py quantitatively complexing 64Cu at room temperature within 5 min (1 × 10− 4 M). [64Cu]Cu-DOTA-xPy (x = 2–4) exhibited good stability in human serum up to 24 h. When challenged with 1000 eq. of NOTA, no transmetallation was observed for all three 64Cu complexes. DOTA-xPy (x = 1–3) were conjugated to a cyclized α-melanocyte-stimulating hormone (αMSH) peptide by using one of the pendant carboxyl groups as a bifunctional handle. [64Cu]Cu-DOTA-xPy-αMSH retained good serum stability (> 96% in 24 h) and showed high binding affinity (Ki = 2.1–3.7 nM) towards the melanocortin 1 receptor. Conclusion DOTA-xPy (x = 1–3) are promising chelators for 64Cu. Further in vivo evaluation is necessary to assess the full potential of these chelators as a tool to enable further theranostic radiopharmaceutical development.

The structural and bonding properties of Bi and Ac complexes with cyclen-based chelating ligands have been studied using relativistic DFT calculations in conjunction with TZ2P all-electron basis sets. Besides the parent cyclen ligand, the study has covered its extensions with pyridine-type (Lpy), carboxylate (DOTA, DOTPA), picolinate (MeDO2PA) and phosphonate (DOTMP) pendant arms. The effect of the cyclen ring size has been probed by increasing it from [12]aneN4 to [16]aneN4. Additional extensions in the DOTA complexes included the H2O ligand at the 9th coordination site as well as the p-SCN-Bn substituent (a popular linker to the targeting vector). The study focuses on the complex stability, the nature of bonding and the differences between Ac and Bi in the complexes. The metal–ligand interactions have been analysed by the Extended Transition State method combined with Natural Orbitals of Chemical Valence theory and Quantum Theory of Atoms in Molecules models. [ABSTRACT FROM AUTHOR]

[Display omitted] • Charge transfer complexes between nano-TiO 2 and malonic acid (TiO 2 -MoA CTCs) were synthesized for the first time. • TiO 2 -MoA CTCs calcined at 270 °C showed a very high surface area (between 306 and 324 m2.g−1). • TiO 2 -MoA-270 CTCs highly absorbed along the visible light spectrum. • TiO 2 -MoA CTCs s how ∼ 100 % degradation of tetracycline under low-power visible light. • TiO 2 -MoA CTCs are an efficient source of photogenerated •O 2 – radicals. Charge transfer complexes (CTCs) between nano-TiO 2 and chelating ligands are among the most promising alternatives for photocatalytic applications, such as environmental remediation. However, the development of CTCs based on nano-TiO 2 modified with malonic acid (MoA) has not yet been investigated in detail. In this study, TiO 2 -MoA CTCs, synthesized via sol–gel route, were tested for tetracycline (antibiotic) and chlorophenol (pesticide) photocatalytic degradation with, and without, scavengers of reactive oxidizing species, under low-power visible light (26 W). The TiO 2 -MoA CTCs were thoroughly characterized. TGA-MS and FTIR analyses revealed malonic acid bonded to the TiO 2 surface, while the PL and EPR analyses proved the generation of extrinsic oxygen vacancies due to calcination process of the xerogels. CTCs based on nano-TiO 2 strongly bonded to malonic acid, and highly sensitive to visible light, have been synthesized by sol–gel method, followed by calcination at 270 °C in air. The as-prepared CTCs showed very high surface areas (between 180.9 and 323.9 m2.g−1), presence of F+ color centers in the calcined CTCs due to extrinsic oxygen vacancies and high photocatalytic activity, degrading approximately 100 % of the tetracycline after 6 h. In addition, it has been proved that the TiO 2 -MoA CTCs are efficient sources of •O 2 – radicals. The findings of this research can be generalized to the synthesis, via sol–gel, of other CTCs between TiO 2 and bidentate ligands, such as dicarboxylic acids, and explored for air purification and hydrogen production. [ABSTRACT FROM AUTHOR]

A survey of the experimental equilibrium constants in solution for the mixed complexes of 4f ions with acidic (chelating) and O-donor organophosphorus ligands published in the period between 1954 and 2022 is presented. These data are widely used in both analytical and solvent extraction chemistry. Important data evaluation criteria involved the specification of the essential reactions, process conditions and the correctness of techniques and calculations used, as well as appropriate equilibrium analysis of experimental data. Higher-quality data have been evaluated, compiled and presented herein, providing a synoptic view of the unifying theme in this area of research, i.e., synergism.

Incorporating nanoparticles into devices for a wide range of applications often requires the formation of thick films, which is particularly necessary for improving magnetic power storage, microwave properties, and sensor performance. One approach to assembling nanoparticles into films is the use of electrophoretic deposition (EPD). This work seeks to develop methods to increase film thickness and stability in EPD by increasing film-substrate interactions via functionalizing conductive substrates with various chelating agents. Here, we deposited iron oxide nanoparticles onto conductive substrates functionalized with three chelating agents with different functional moieties and differing chelating strengths. We show that increasing chelating strength can increase film-substrate interactions, resulting in thicker films when compared to traditional EPD. Results will also be presented on how the chelating strength relates to film formation as a function of deposition conditions. Yield for EPD is influenced by deposition conditions including applied electric field, particle concentration, and deposition time. This work shows that the functionalization of substrates with chelating agents that coordinate strongly with nanoparticles (phosphonic acid and dopamine) overcome parameters that traditionally hinder the deposition of thicker and more stable films, such as applied electric field and high particle concentration. We show that functionalizing substrates with chelating agents is a promising method to fabricate thick, stable films of nanoparticles deposited via EPD over a larger processing space by increasing film-substrate interactions.

Metal uptake, transport and storage in plants depend on specialized ligands with closely related functions. Individual studies differing by species, nutrient availability, tissue type, etc. are not comprehensive enough to understand plant metal homeostasis in its entirety. A thorough review is required that distinguishes the role of ligands directly involved in chelation from the myriad of plant responses to general stress. Distinguishing between the functions of metal chelating compounds is the primary focus of this review; reactive oxygen species mediation and other aspects of metal homeostasis are also discussed. High molecular weight ligands (polysaccharides, phytochelatin, metallothionein), low molecular weight ligands (nicotianamine, histidine, secondary metabolites) and select studies which demonstrate the complex nature of plant metal homeostasis are explored. • The function of chelating ligands in plants requires further clarification. • Metal binding properties alone do not fully describe the function of ligands. • Notable studies and lacking areas of research in plant homeostasis are explored. • Iron-chelating phytotoxins may serve primarily as phytosiderophores. • Metal hyperaccumulators uniquely demonstrate the role of ligands in homeostasis. [ABSTRACT FROM AUTHOR]

A series of Ni/ZrO 2 catalysts was prepared by the impregnation method with modification of the morphology of ZrO 2 support as well as the impregnation procedure and tested for CO 2 methanation. The catalysts supported on the ZrO 2 nanosheets displayed superior catalytic performance as compared with that on ZrO 2 nanoparticles, which could be mainly attributed to the abundant oxygen vacancies promoting the adsorption and dissociation of CO 2 molecules as well as the high dispersion of Ni species. With the introduction of ethylenediamine (En) in the impregnation procedure, the resulting Ni-15En/ZrO 2 -1.5 catalyst showed the optimal activity with CO 2 conversion of 86% significantly higher than Ni/ZrO 2 -0 of 44% and Ni/ZrO 2 -1.5 of 79% at 0.5 MPa and 300 °C. The excellent performance was attributed to increased moderately basic sites for CO 2 adsorption in ZrO 2 nanosheets, as well as the enhanced dispersion of nickel caused by the complexation of Ni ions with En, which inhibited the aggregation of nickel particles in the subsequent thermal treatments. In conclusion, the synergistic effects of the morphology of ZrO 2 nanosheets as well as the chelating behavior of En contributed to the enhanced performance of Ni-15En/ZrO 2 -1.5 in the CO 2 methanation reaction. The strategy shows good prospects for controlling the size of active metals, especially those that were dispersed on the surface of the two-dimensional (2D) metal oxide materials. • Nickel supported on ZrO 2 nanosheets exhibited superior CO 2 methanation activity than that on ZrO 2 nanoparticles. • Abundant oxygen vacancies in ZrO 2 nanosheets promoted the CO 2 adsorption and activation. • Stronger metal-support interaction caused higher nickel dispersion on nanosheets than on nanoparticles. • Adding ethylenediamine in the impregnation process further improved Ni dispersion and oxygen defects on ZrO 2 nanosheets. • Both nanosheet morphology and chelating effect of ethylenediamine afford enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Chelating phosphines have long been a mainstay as efficient directing ligands in transition‐metal catalysis. Low‐valent derivatives, namely chelating phosphinidenes, are to date unknown, and could lead to chelating complexes containing more than one metal centre due to the intrisic capacity of phosphinidenes to bind two metal fragments at one P‐centre. Here we describe the synthesis of the first such chelating bis‐phosphinidene ligand, XantP2 (2), generated by the reduction of a diphosphino xanthene derivative, Xant(PH2)2 (1) with iPrNHC (iPrNHC=[:C{N(iPr)C(H)}2]). Initial studies have shown that this novel chelating ligand can act as a bidentate ligand towards element dihalides (i.e. FeCl2, ZnI2, GeCl2, SnBr2), forming cationic complexes with the tetryl elements. In contrast, XantP2 demonstrates an ability to bind multiple metal centres in the reaction with CuCl, leading to a cationic Cu3P3 ring complex, with Cu centres bridged by phosphinidene arms. Density Functional Theory calculations show that 2 indeed holds 4 lone pairs of electrons, shedding further light on the coordination capacity for this novel ligand class through observation of directionality and hybridisation of these electron pairs. [ABSTRACT FROM AUTHOR]

Background: 64Cu is one of the few radioisotopes that can be used for both imaging and therapy, enabling theranostics with identical chemical composition. Development of stable chelators is essential to harness the potential of this isotope, challenged by the presence of endogenous copper chelators. Pyridyl type chelators show good coordination ability with copper, prompting the present study of a series of chelates DOTA-xPy (x = 1–4) that sequentially substitute carboxyl moieties with pyridyl moieties on a DOTA backbone. Results: We found that the presence of pyridyl groups significantly increases 64Cu labeling conversion yield, with DOTA-2Py, −3Py and -4Py quantitatively complexing 64Cu at room temperature within 5 min (1 × 10− 4 M). [64Cu]Cu-DOTA-xPy (x = 2–4) exhibited good stability in human serum up to 24 h. When challenged with 1000 eq. of NOTA, no transmetallation was observed for all three 64Cu complexes. DOTA-xPy (x = 1–3) were conjugated to a cyclized α-melanocyte-stimulating hormone (αMSH) peptide by using one of the pendant carboxyl groups as a bifunctional handle. [64Cu]Cu-DOTA-xPy-αMSH retained good serum stability (> 96% in 24 h) and showed high binding affinity (Ki = 2.1–3.7 nM) towards the melanocortin 1 receptor. Conclusion: DOTA-xPy (x = 1–3) are promising chelators for 64Cu. Further in vivo evaluation is necessary to assess the full potential of these chelators as a tool to enable further theranostic radiopharmaceutical development. [ABSTRACT FROM AUTHOR]

Binding of bismuth cation with two newly synthesized picolinate containing acyclic (L1) and macrocyclic (L2) ligands was studied. Both ligands demonstrate complex formation with Bi3+ under ambient conditions with high complexation constants. Serum stability of the complexes was investigated in serum protein excess of 10- and 100-times. Experiments with no-carrier-added radiobismuth (207Bi and 213Bi) were performed. A one-column 225Ac/213Bi generator system, based on Ac resin (Triskem Inc.), was tested. The overall yield of 213Bi was exceeding 85% with 225Ac breakthrough below 10−4%. [ABSTRACT FROM AUTHOR]

Tenatumomab is an anti-tenascin murine monoclonal antibody previously used in clinical trials for delivering radionuclides to tumors by both pre-targeting (biotinylated Tenatumomab within PAGRIT) and direct 131Iodine labeling approaches. Here we present the synthesis and in vitro characterization of three Tenatumomab conjugates to bifunctional chelating agents (NHS-DOTA, NCS-DOTA and NCS-DTPA). Results indicate ST8198AA1 (Tenatumomab-DOTAMA, derived by conjugation of NHS-DOTA), as the most promising candidate in terms of conjugation rate and yield, stability, antigen immunoreactivity and affinity. Labeling efficiency of the different chelators was investigated with a panel of cold metals indicating DOTAMA as the best chelator. Labeling of Tenatumomab-DOTAMA was then optimized with several metals and stability performed confirms suitability of this conjugate for further development. ST8198AA1 represents an improvement of the previous antibody forms because the labeling with radionuclides like 177Lu or 64Cu would allow theranostic applications in patients bearing tenascin expressing tumors. [ABSTRACT FROM AUTHOR]

Six new green to yellow-emitting heteroleptic bis-cyclometalated iridium(III) complexes of the type Ir(C⁁N)2(L⁁X) (C⁁N = cyclometalating ligand, L⁁X = monoanionic chelating ancillary ligand) bearing two widely used cyclometalating ligands (C⁁N = 2-(2-thienyl)pyridine (thpy) and 2-phenylbenzoxazole (bo)) and six different ancillary ligands were prepared. In this study, the complexes include structurally diverse ancillary ligands that allow us to investigate several aspects of structure-property relationships. Ancillary ligands used in this study are small-bite-angle N-phenylacetamidate (paa), N-isopropylbenzamidate (ipba) and N,N′-diisopropylbenzamidinate (dipba), and larger bite-angle β-ketoiminate (acNac), β-diketiminate (NacNac), and β-thioketoiminate (SacNac). The emission color is governed by the choice of the cyclometalating ligand, but the ancillary ligands influence the electrochemical and photophysical properties. Electrochemical analysis shows that the energy of the HOMO varies substantially as the L⁁X structure is altered, whereas the energy of LUMO remains nearly constant. The emission maxima range from 537 nm to 590 nm, with solution quantum yields between 0.0094 and 0.60 and microsecond lifetimes. The results here reveal the ancillary ligands provide a channel to control redox properties and excited-state dynamics in cyclometalated iridium complexes that luminesce in the middle regions of the visible spectrum. [ABSTRACT FROM AUTHOR]

• Titanyl compounds can form chain-like or cyclic structures, but no clusters with μ 3 -O. • The ligands compensate the charge of TiO2+ and complete the coordination shell of the Ti atoms. • The ligand have great influence on whether titanyl compounds or titanium oxo clusters with μ 3 -O are formed. Chain-like and cyclic structures of compounds with a ⋯Ti–O–Ti–O⋯ backbone are reviewed, that is, compounds in which the coordination octahedra of the titanium atoms share corners by means of μ 2 -O atoms. The charge of the TiO2+ unit is balanced by organic or inorganic ligands which additionally complete the coordination sphere of the titanium atoms. Typical substitution patterns are two mono-anionic bidentate ligands, two monodentate anionic plus two neutral ligands, or one tetradentate dianionic ligand. While only few examples of polymeric chain structures, or segments thereof, were structurally characterized, several types of cyclic compounds are known. This includes rings in which the Ti polyhedra are only linked via the μ 2 -O atoms, capped rings, or rings in which the titanium octahedra are additionally bridged by organic ligands. [ABSTRACT FROM AUTHOR]

Considerable research effort has focused on the in vivo use of responsive imaging probes that change imaging properties upon reacting with oxygen because hypoxia is relevant to diagnosing, treating, and monitoring diseases. One promising class of compounds for oxygen-responsive imaging is EuII-containing complexes because the EuII/III redox couple enables imaging with multiple modalities including magnetic resonance and photoacoustic imaging. The use of EuII requires care in handling to avoid unintended oxidation during synthesis and characterization. This review describes recent advances in the field of imaging agents based on discrete EuII-containing complexes with specific focus on the synthesis, characterization, and handling of aqueous EuII-containing complexes.

Background: Flavonoids and their analogous are mainly found in pink lady apples, green and black tea (catechins), celery and red peppers, onions, broccoli and spinach, berries, cherries, soybean, citrus fruits, and fungi. The different derivatives of flavonoids belonging to polyphenolic compounds such as 3,4',5,7-Tetrahydroxyflavylium (pelargonidin), 2-(3,4-Dihydroxyphenyl)chromenylium-3,5,7-triol (cyanidin), 3,3',4',5,5',7-Hexahydroxyflavylium (delphinidin), 3,3',4',5,7-Pentahydroxy-5'-methoxyflavylium (petunidin), and 3,4',5,7-Tetrahydroxy-3',5'-dimethoxyflavylium (malvidin) can act as good chelating agents for metal-chelate complex formation. These flavonoid-metal complexes have been reported to have various biomedical and pharmacological activities., Objective: Flavonoid-metal ion complexes display a broad spectrum of biological properties such as antioxidant, anti-inflammatory, anti-allergic, antiviral, anticarcinogenic, and cytotoxic activity. The literature survey showed that flavonoid metal complexes have potential therapeutic properties against various cancerous cells. The objective is to gain insight into the current perspective and development of novel anticancer metallodrugs., Methods: The flavonoid-metal ion complexes can be prepared by reacting flavonoid ligand with appropriate metal salt in aqueous or alcoholic reaction medium under stirring or refluxing conditions. In this review article, the various reported methods for the synthesis of flavonoid-metal complexes have been included. The utility of synthetic methods for flavonoid-metal complexes will support the discovery of novel therapeutic drugs., Results: In this review study, short libraries of flavonoid-metal ion complexes were studied as potential anticancer agents against various human cancer cell lines. The review report reveals that metal ions such as Fe, Co, Ni, Cu, Zn, Rh, Ru, Ga, Ba, Sn etc., when binding to flavonoid ligands, enhance the anticancer activity compared to free ligands. This review study covered some important literature surveys for the last two decades., Conclusion: It has been concluded that flavonoid metal complexes have been associated with a wide range of biological properties that could be noteworthy in the medicinal field. Therefore, to develop a new anticancer drug, it is essential to determine the primordial interaction of drug with DNA under physiological or anatomical conditions. The study of numerous flavonoid metal complexes mentioned in this paper could be the future treatment against various cancerous diseases., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Nucleophilic attack on complex [RuCl(η6‐C10H14){κ3(P,C,C)‐Ph2PCH2CH=CH2}][BPh4] (2) takes place, either to the metal or to the coordinated olefin depending on the nucleophile and the reaction conditions. The nucleophilic attack of phosphanes on the coordinated olefin leads diastereoselectively to complexes [RuCl(η6‐C10H14){ĸ2(P,C)‐Ph2PCH2CH(PR3)CH2}]+ bearing κ2(P,C)‐ligands obtained as a racemic mixture of the enantiomers RRuSc/SRuRC. These kinetically stable isomers, undergo an isomerization process leading to the thermodynamically stable products isolated as the diastereoisomer RRuRC/SRuSC. 31P{1H} NMR monitoring experiments on the isomerization processes have been carried out. New Ru complexes containing bidentate κ2(P,C)‐ligands [RuCl(η6‐C10H14){ĸ2(P,C)‐Ph2PCH2CH(PR3)CH2}][BPh4] have been diastereoselectively synthesized as the kinetically stable isomer (RRuSC/SRuRC). This diastereoisomer spontaneously evolves to the thermodynamically stable diastereoisomer (RRuRC/SRuSC). 31P{1H} NMR monitoring experiments shed light on the isomerization processes. [ABSTRACT FROM AUTHOR]

Iron (Fe) is an important nutrient for phytoplankton. The low solubility of Fe in oxic waters can be a growth-limiting factor for phytoplankton. Synthetic aminopolycarboxylates (APCs) such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are widely used as Fe complexing agents for microalgae culture. However, the presence of these non-ready biodegradable APCS in aquatic systems may have serious environmental consequences. In the present study, the effects of biodegradable chelating ligands (hydroxyiminodisuccinic acid (HIDS), methylglycinediacetic acid (MGDA), and iminodisuccinate (IDS)) on Fe uptake in and growth of three coastal microalgae (Heterosigma akashiwo, Prymnesium parvum, and Skeletonema marinoi-dohrnii complex) were investigated, and the results were compared with those of non-ready biodegradable APCs (EDTA, ethylenediamine tetra-methylene phosphonic acid (EDTMP), and DTPA). The biodegradable chelating ligands did not have significant growth inhibition effect on the phytoplankton. Although the growth of the algae (except S. marinoi-dohrnii complex) was not affected substantially by 1.5 and 7.5 μM of DTPA, growth inhibition occurred by 7.5 μM of EDTMP and 150 μM of EDTA, DTPA, and EDTMP. The effect of chelating ligands on microalgal growth was likely to be associated with the intracellular Fe uptake influenced by the chelating ligands. On average, intracellular Fe concentrations for biodegradable chelating ligands were substantially higher than those for non-ready biodegradable APCs. Except H. akashiwo, the ratio of intra/extracellular Fe concentrations was highest for MGDA followed by IDS and HIDS. The results indicate that biodegradable chelating ligands are more efficient than non-ready biodegradable APCs in intracellular Fe uptake and algal growth. [ABSTRACT FROM AUTHOR]

This review provides a summary, including spectroscopic and structural data, of the metal complexes accessible with mono-oxide, sulfide and selenide bis(diphenylphosphino)amine (DPPA)-based ligands and their N -substituted/functionalized derivatives. The nature of the E (O, S, Se) donor in these mixed P ,P E donor ligands strongly influences the nature of the resulting metal complexes, which can incorporate the DPPA-type ligand(s) as P -monodentate or P , E -chelate. When available, a comparison between the reactivity of the mixed P ,P E and parent P , P systems is given. The catalytic applications of P , E -supported metal complexes are also discussed. [ABSTRACT FROM AUTHOR]

Substitution at a B-H unit of the heteroborate cluster stanna- closo-dodecaborate [SnB11H11]2- at the upper belt of the icosahedron by one of the triarylphosphine moieties of xantphos was carried out under the catalysis of palladium acetate. The resulting coupling product is a monoanion offering two coordination sites: a low-valent tin-cluster vertex and a triaryl phosphine moiety. The basicity and nucleophilicity of the anion were investigated in reactions with a strong acid or an alkylating agent. Transition-metal electrophiles like platinum halide PtCl2 or rhodium carbonyl [Rh(CO)2Cl]2 react with the bidentate ligand, with the formation of cis-coordination products. [ABSTRACT FROM AUTHOR]

Influenza virus is an hot topic in medicinal chemistry and great efforts are ongoing for the discover of new antivirals able to overcome problems related to resistant strains and adverse side effects of current drugs. Influenza virus endonuclease is an attractive target for antiviral drug development and in particular the strategy to chelate the metal ion(s) within the active site proved to be an efficient mode to inhibit enzymatic activity. Our previous findings revealed that 2-hydroxyamide derivatives are able to chelate Mg 2+ ions, forming complexes with different stoichiometric ratios. Here we report on the activity of the three ligands N -(4-fluorobenzyl)-2-hydroxybenzamide, N -(4-fluorobenzyl)-2,3-dihydroxybenzamide, and N1,N3 -bis(4-fluorobenzyl)-2-hydroxyisophthalamide, containing the salicylic group, and their Mg 2+ complexes (7)–(9) , evaluated by means of virus yield assay in influenza virus-infected MDCK cells and vRNP reconstitution assay in HEK293T cells. In some cases, promising anti-influenza activities with EC 50 values in the low micromolar range were found. As a contribute to clarify the activity in cells of the ligands, here we also present a study on the their coordinating properties towards the other essential metal ion Cu(II), carried out by potentiometric and calorimetric measurements. [ABSTRACT FROM AUTHOR]