Search Results (318)

In this study, three new terphenyl-substituted NPN ligands bearing pyridyl groups, two phosphonites and one diaminophosphine, were synthesized and fully characterized. Their coordination chemistry with copper(I) was investigated using CuBr and [Cu(NCMe)₄]PF₆ as metal precursors, affording six mononuclear Cu(I) complexes, which were characterized using NMR spectroscopy and, in selected cases, single-crystal X-ray diffraction (SCXRD) analysis. The NPN ligands adopt a κ³-coordination mode, stabilizing the copper centers in distorted tetrahedral geometries. The catalytic performance of these complexes in the S-arylation of thiols with aryl iodides was evaluated. Under optimized conditions, complexes 2a and 2b exhibited excellent activity and broad substrate scope, tolerating both electron-donating and electron-withdrawing groups, as well as sterically hindered and heteroaryl substrates. The methodology also proved effective for aliphatic thiols and demonstrated high chemoselectivity in the presence of potentially reactive functional groups. In contrast, aryl bromides and chlorides were poorly reactive under the same conditions. These findings highlight the potential of well-defined Cu(I)–NPN complexes as efficient and versatile precatalysts for C–S bond formation. Full article

The polymerization of norbornene can occur via ring-opening metathesis polymerization (ROMP) or vinyl-addition pathways, each yielding polynorbornene with distinct structures and properties. This study reports on the synthesis and catalytic application of a new class of vanadium(III) and nickel(II) complexes bearing N-heterocyclic carbene ligands, based on the IPr* framework, for the polymerization of norbornene. The vanadium(III) complexes, activated by diethylaluminum chloride and in the presence of ethyl trichloroacetate, showed activity in ROMP. In contrast, the nickel(II) complexes, activated by methylaluminoxane, exhibited catalytic activity toward vinyl-addition polymerization. Characterization by GPC, NMR, and FTIR confirmed the formation of both ring-opening metathesis polymerization and vinyl-type-derived polynorbornenes, with vinyl-type polymers showing significantly higher molecular weights. Structural variations in the N-heterocyclic carbene ligands, particularly the linker length between imidazole donors, were found to strongly influence polymer molecular weight and the morphology of polynorbornenes. Full article

Topping is an essential step in cotton cultivation in Xinjiang, China, which can effectively increase the number of bolls per plant and optimize the yield and quality. Paclobutrazol, as a common chemical topping agent for cotton, faces challenges such as unstable topping effect and limited leaf surface absorption during application. In this study, paclobutrazol was used as the ligand and a zinc complex was synthesized by the thermosolvent method to replace paclobutrazol and improve the topping effect on cotton. The structure of the complex was characterized using FTIR, UV-vis, TG, and XRD analyses. The results confirmed that each zinc ion coordinated with four nitrogen atoms from the triazole rings of paclobutrazol and two oxygen atoms from nitrate ions, forming an octahedral geometry. Surface tension measurement and analysis revealed that the complex had a surface tension reduction of 12.75 mN/m compared to paclobutrazol, thereby enhancing the surface activity of the complex in water systems and improving its absorption efficiency on plant leaves. Two-year field trials indicated that the foliar application of the complex at a dosage of 120 g·hm⁻² in inhibiting cotton plant height was more stable to that of paclobutrazol or mepiquat chloride. It also shortened the length of fruiting branches, making the shape of cotton plants compact, thereby indirectly improving the ventilation and light penetration of the cotton field and the convenience of mechanical harvesting. Yield data showed that, compared with artificial topping, the complex at a dosage of 120 g·hm⁻² treatment increased cotton yield by approximately 4.6%. Therefore, the paclobutrazol–zinc complex is a promising alternative to manual topping and have great application potential in future mechanized cotton production. Full article

Four new arene–ruthenium(II) complexes [(η⁶-p-cymene)RuCl(dpm)], where dpm are hexa-(L3–L5) and meso-substituted (L6) dipyrromethene ligands, were synthesized. These ligands and the corresponding complexes were thoroughly characterized by elemental analysis and spectroscopic techniques (MS, IR, ¹H, ¹³C NMR, and UV–vis), and the structures of one ligand and three ruthenium complexes were determined by X-ray single-crystal analysis. The DNA-binding ability of the Ru-3–Ru-6 complexes was evaluated by UV–vis DNA titration. Compound Ru-3 exhibited the highest binding energy, outperforming the complexes containing a dipyrrin ligand substituted by chlorides (Ru-4 and Ru-5) or a meso-substituted dipyrrin (Ru-6). Molecular docking revealed that the hypothetical Ru-1 and Ru-2 complexes, which contain iodide ligands in the dipyrrin structures, showed higher DNA-binding affinities than Ru-3. Computational calculations supported the experimental results, confirming that Ru-3 has a higher affinity for DNA than the other complexes. Full article

Photocatalytic CO₂ conversion is one of the ideal approaches to address both topics of solar energy shortage and carbon neutrality. Cobalt(II) centers coordinated with bipyridines have been designed and evaluated as catalysts for CO₂ conversion under light irradiation. Herein, we report a series of pyridine-based cobalt complexes with alkyl substituents as molecular photocatalysts, aiming to elucidate the effects of alkyl type and substitution position on catalytic performance through spectroscopic and electrochemical measurements. The substitution of the hydrogen at 4,4′-positions on the bipyridine ring with a methyl group, a tert-butyl group, and a nonyl group led to a decrease in the conversion rate of CO₂ by 13.2%, 29.6%, and 98%, respectively. The methyl substituents at the 5, 5′-positions of the bipyridine ring resulted in a 71.1% decrease in the CO₂ conversion rate. The usage of either 6, 6′-Me₂-2,2′-bipy, 2,4-bipy, or 3,3′-bipy resulted in no detectable activity for CO₂ conversion in the current system. Both photo- and electrochemical analyses have been employed to reveal the relationship between changing ligands and photocatalytic performance on the molecular scale. These results demonstrate that bulky ligands significantly hinder CO₂ reduction by cobalt complexes due to steric interference with coordination and active-site accessibility. This study demonstrates that the substituent effect of ligands on photocatalytic reactions for CO₂ conversion provides valuable insight into a deeper understanding of molecular catalysis. Full article

Hydrogen peroxide (H₂O₂) is an important industrial chemical that is widely applied in many areas. The direct synthesis of H₂O₂ from H₂ and O₂ has proved to be a green and economic pathway. Pd-based bimetallic catalysts, due to their superior catalytic performances in this reaction, have attracted intensive attention. Herein, Tetrakis(hydroxymethyl)phosphonium chloride (THPC) was adopted as the protective ligand to immobilize Pd-Au alloy nanoparticles onto activated carbon (AC). The varied Pd/Au molar ratios demonstrated homogeneously distributed Pd-Au nanoalloys with average particle sizes ranging from 3.51 to 5.75 nm. The optimal ratio was observed over the Pd₃Au₁/AC-THPC catalyst with a maximum H₂O₂ productivity of 165 mol/(kg_Pd·h) and selectivity of 82.3% under ambient pressure. The relationship between the electronic structure and catalytic activity indicated Pd⁰ was the active site, while the presence of Au inhibited H₂O₂ degradation rate. This research could help in the design efficient bimetallic catalysts for the direct synthesis of H₂O₂. Full article

Diphosphine compounds have been used as ligands for a variety of metals, and studies on their structures and reactivities are still of interest. We investigated the coordination chemistry of P–P-bonded diphosphine by conducting reactions of bis(1,1′-dibenzophospholyl) (Db)₂P–P(Db)₂ 1 with d⁰-titanium(IV) reagents. The reaction of 1 with TiCl₄ afforded the dinuclear titanium complex Cl₃Ti{μ-(Db)₂P–P(Db)₂}(μ-Cl)₂TiCl₃ 2. The final structure of titanium complex 2 was determined by single-crystal X-ray structural analysis. The molecular structure of the complex was found to be a dinuclear d⁰-titanium complex coordinated to diphosphine on the same side, and the central titanium atoms were bridged to each other by chlorides. To further elucidate this complex, density functional theory (DFT) calculations were conducted to analyze its structure. Full article

This study explores the use of a deep eutectic solvent (DES) composed of choline chloride and pyrogallol (1:1 molar ratio) for the recovery of lithium, cobalt, and nickel from spent lithium-ion battery cathodes based on LiNi_0.33Co_0.33Mn_0.33O₂ (NMC111). The DES exhibits moderate viscosity, intrinsic redox activity, and strong complexation ability, enabling efficient metal dissolution under mild conditions. The effects of both temperature (50–80 °C) and time (up to 12 h) on leaching efficiency were systematically investigated. Optimal leaching parameters—80 °C, 8 h, and a liquid-to-solid ratio of 50—yielded extraction efficiencies of 92% for Li, 85% for Co, and 88% for Ni. Kinetic modeling indicated pseudo-first-order behavior with activation energies of 26.6, 22.1, and 25.2 kJ/mol for Li, Co, and Ni, respectively. Mechanistic analysis confirmed the dual role of pyrogallol as both reducing agent (facilitating Co³⁺ to Co²⁺ conversion) and chelating ligand. Full article

This work presents the synthesis routes for the first representatives of cadmium complexes based on 1,2-bis(arylimino)acenaphthene (Ar-bian). The reaction of CdCl₂ with bis-(2,4,6-trimethylphenylimino)acenaphthene (tmp-bian) in a 1-to-1 molar ratio led to a dimeric complex [Cd₂(tmp-bian)₂Cl₂(µ-Cl)₂] (1). Further treatment of complex 1 with silver triflate as a chloride-eliminating agent, followed by the addition of one equivalent of tmp-bian, resulted in the formation of a mixture consisting of [Cd₂(tmp-bian)₂(H₂O)₄(µ-Cl)₂](OTf)₂ (2) and [Cd(tmp-bian)₂(OTf)₂] (3). To obtain complex 3 in its individual form, a reaction of Cd(OTf)₂ with two equivalents of tmp-bian was carried out. The characterization of the complexes was conducted through a range of analytical methods, including X-ray diffraction analysis, elemental analysis, as well as IR and ¹H NMR-spectroscopies. Redox properties of 1 and 3 were investigated by means of cyclic voltammetry. Cyclic voltammograms revealed irreversible reduction processes centered on the tmp-bian ligand, which were confirmed by quantum chemical calculations. Full article

Deep eutectic solvents (DESs) have shown promise as a medium for extracting polar volatile fatty acids (VFAs) and in situ esterification of the extracted molecules using lipases. This solvent enhanced biocatalysis process can potentially streamline VFA separation from fermentation broth by integrating conversion and extraction steps. Two commercial lipases from Aspergillus oryzae (AoL) and Candida rugosa (CrL) were evaluated in reaction systems containing hydrophilic or hydrophobic DESs using a newly optimized lipase assay. The optimal pH for both lipases was around 5.0, with a slight reduction in activity at pH 8.0 and a significant inhibition at pH 2.0. The impact of DES concentration on lipase activity varied depending on the specific DES–lipase pairs. Most hydrophilic DESs show good compatibility with the tested lipases. Specifically for choline chloride/ethylene glycol (1:2) and choline chloride/levulinic acid (1:2), taking into account the influence of pH, CrL activity increased with DES concentration. However, the hydrophobic DES thymol/2,6-dimethoxyphenol (1:2) demonstrated enhanced inhibitory effects on both lipases. Docking simulation helped explain the ligand–protein interactions but showed limited capability in predicting the compatibility of specific DES–lipase pairs due to its constraints in simulating flexible protein structures and the complex interactions between DES components and water. Full article

The synthesis of (E)-1-(1-benzyl-5-methyl-1H-1,2,3-triazol-4-yl)-3-phenyl-2-propen-1-one derivatives was carried out in two steps, using benzylic chloride derivatives as starting material. The structural determination of intermediates and final products was performed by spectroscopic methods: infrared spectroscopy, nuclear magnetic resonance spectroscopy and mass spectrometry (IR, NMR, and MS). In vitro evaluation of cytotoxic activity on adherent and non-adherent cells showed that triazole chalcones exhibited significant activity against three of the five cell lines studied: non-Hodgkin lymphoma U937, glioblastoma multiform tumor T98G, and gallbladder cancer cells Gb-d1. In contrast, the cytotoxic activity observed for cervical cancer HeLa and gallbladder adenocarcinoma G-415 was considerably lower. Additionally, in the cell lines where activity was observed, some compounds demonstrated an In vitro inhibitory effect superior to that of the control, paclitaxel. Molecular docking studies revealed specific interactions between the synthesized ligands and therapeutic targets in various cell lines. In U937 cells, compounds 4a and 4c exhibited significant inhibition of vascular endothelial growth factor receptor (VEGFR) kinase, correlating with their biological activity. This effect was attributed to favorable interactions with key residues in the binding site. In T98G cells, compounds 4r and 4w showed affinity for transglutaminase 2 (TG2) protein, driven by their ability to form hydrophobic interactions. In Gb-d1 cells, compounds 4l and 4p exhibited favorable interactions with mitogen-activated protein kinase (MEK) protein, similar to those observed with the known inhibitor selumetinib. In HeLa cells, compounds 4h and 4g showed activity against dihydrofolate reductase (DHFR) protein, driven by hydrogen bonding interactions and favorable aromatic ring orientations. On the other hand, compounds 4b and 4t exhibited no activity, likely due to unfavorable interactions related to halogen substitutions in the aromatic rings. Full article

The increasing demand for critical metals has intensified efforts to recover valuable metals from various sources, including secondary waste. Zn-Pb tailings contain both major and trace metals with economic and environmental significance. This study examined the extraction of transition metals from Zn-Pb tailings using inductively coupled plasma mass spectrometry (ICP-MS) at a constant time of 30 min. Metal extraction efficiencies were evaluated using N-Methyl-N,N,N-trioctylammonium chloride (Aliquat 336), methyl salicylate (MS), di(2-ethylhexyl) phosphoric acid (D2EHPA), tributyl phosphate (TBP),2,4,6-tris(allyloxy)-1,3,5-triazine (TAOT), and triethyl phosphate (TEP). Increasing mixing rates improved mass transfer, enhancing recoveries, with Hf⁴⁺, Ti⁴⁺, and Fe³⁺ reaching 88, 56, and 50%, respectively, at 1000 rpm (mixing rate; rotation per minute) using D2EHPA. At a mixing rate of 1000 rpm, 10% TEP recovered 25% of Cu²⁺ and 34% of Mn²⁺, while 150 g/L extracted 48% of Hf⁴⁺ and 46% of V⁴⁺. Additionally, 10% TBP extracted 33% of Mn²⁺ and 35% of V⁴⁺, 10% MS recovered 41% of Mn²⁺ and 39% of V⁴⁺, while TAOT extracted 35% of V⁴⁺. At room temperature (22.5 °C) and 1400 rpm, 10% of D2EHPA recovered 80% of Hf⁴⁺, 73% of Ti⁴⁺, and 61% of Fe²⁺. However, 10% TAOT selectively recovered 50% of V⁴⁺, while 10% MS, under the same conditions, recovered 50% of V⁴⁺ with co-extraction of Mn²⁺ and Cu²⁺ (<10%). A total of 150 g/L Aliquat 336 effectively extracted Hf⁴⁺ (66%), Zn²⁺ (19%), and V⁴⁺ (56%). A total of 10% TBP recovered 53% and 47% of Mn²⁺ and V⁴⁺, respectively. A total of 10% TEP recovered Cu²⁺ (45%), Mn²⁺ (55%), Zn²⁺ (29%), V (40%), and 26% of Ni²⁺. At room temperature (22.5 °C) and 1400 rpm, pH changes significantly affected extraction, with D2EHPA (10%) demonstrating 89% efficiency for Hf⁴⁺ at pH 1.3, while other metals showed lower recoveries. TEP (10%) increased Cu²⁺ and Hf⁴⁺ recovery to 52% and 80%, respectively, at pH 1.3, while 150 g/L Aliquat 336 favored Cu²⁺ (58%), with co-extraction of 16% of Zn²⁺ at pH 1.3. TBP (10%) extracted 60% and 61% of Cu²⁺ and Fe, respectively, at pH 1.3, while 10% of MS recovered 55% and 50% of V, respectively. A concentration of 10% D2EHPA favored the recovery of 90% of Hf⁴⁺ at pH 1.3, with less than 35% co-extraction of Cu²⁺, Mn²⁺, Zn²⁺, and Fe²⁺. At 1400 rpm, temperature also influenced extraction, with D2EHPA recovering 84% of Hf⁴⁺ at 35 °C, 77% of Ti (55 °C), and 79% of Fe (55 °C) and TBP extracting 73% of Cu²⁺, 67% of Mn²⁺, 68% of Zn, 60% of V⁴⁺, and 47% of Ni²⁺ at 55 °C. A concentration of 10% MS extracted 61% of V⁴⁺and 54% of Fe²⁺, while 150 g/L recovered 61% of V⁴⁺ at 55 °C. TAOT extracted 46% of Mn and 41% of V⁴⁺, while 10% TEP recovered 60% of Mn and 32% of V⁴⁺ at 55 °C. These outcomes contribute to an improved understanding of the solvent extraction mechanisms of different ligands. Full article

Polystyrene-supported chiral hydroxyamide-functionalized benzimidazolium chloride was synthesized by reacting Merrifield resin with a substituted-azole derived from (S)-leucinol. The combination of [IrCl(cod)]₂ and the resulting polymer-supported N-heterocyclic carbene (NHC) ligand precursor catalyzed the enantioselective reduction of ketones using (EtO)₂MeSiH under heterogeneous reaction conditions via a pre-mixing reaction procedure. Additionally, the solid-state resin could be easily recovered through simple filtration and the catalyst system’s reusability was evaluated. Full article

In this study, the photophysical properties of thin films of an Eu³⁺ dye, namely europium tetrakis(dibenzoylmethide) triethylammonium (EuD₄TEA), within deoxyribonucleic acid (DNA) biopolymer functionalized with hexadecyltrimethylammonium chloride (CTMA) were extensively investigated and compared with those of thin films of the same dye embedded in more conventional polymers, like poly(methyl methacrylate) and polycarbonate. The new materials obtained have good optical properties, as shown by their absorption and emission spectra. Remarkably, a large enhancement in photoluminescence was observed upon the interaction of EuD₄TEA with DNA-CTMA (2- and 17-fold increase in luminescence quantum yield with respect to PMMA and PC). Photophysical analyses suggest that the emission enhancement was mainly due to the increase in the sensitization efficiency (η_sens) from the ligands to the Eu³⁺ ion along with the suppression of the vibrational deactivation upon immobilization onto the DNA-CTMA matrix, as the concentration of the complex increased from 20 to 50%. These phenomena are primarily driven by the transformation of the Eu³⁺ micro-environments, which are created by the interactions between complex ligands and the DNA-CTMA matrix. Full article

The sustainable management of industrial byproducts represents a critical challenge for the aluminum industry. This study developed a cost-effective adsorbent (SA@RM) derived from sodium alginate and red mud for fluoride removal, addressing both solid waste utilization and water purification needs. Systematic adsorption experiments revealed optimal performance under conditions of 15 g/L dosage and pH 5, achieving adsorption equilibrium within 40 min for initial fluoride concentrations of 11.7 mg/L. Notably, the adsorbent demonstrated exceptional cyclic stability, maintaining 54.8% adsorption capacity through three regeneration cycles. The adsorption process followed the Langmuir isotherm model (R² = 0.994) and pseudo-second-order kinetics (R² = 0.975), indicating monolayer chemisorption as the dominant mechanism. Advanced characterization techniques (SEM-EDS, FT-IR, XPS) elucidated three main mechanisms: fluoride complexation with aluminum oxides, ligand exchange with surface hydroxyl groups, and ion exchange with chloride species. This material achieves 92% fluoride removal while valorizing industrial waste, reducing adsorbent production costs by 60–70% compared to conventional materials. The detailed mechanism analysis provides fundamental insights for designing waste-derived adsorbents, offering a practical solution for sustainable industrial development and water treatment applications. Full article