Transition Metal Chemistry最新文献

The pyrazine-modulated oligo-α-pyridylamino ligand N,N′-di(pyrazin-2-yl)pyridine−2,6-diamine (H₂dpzpda) was used to synthesize and structurally characterize two novel mononuclear copper(II) complexes. In both complexes, H₂dpzpda acts as a tridentate ligand and coordinates to the metal center in an all-anti conformation. Complex 1 exhibits a distorted trigonal–bipyramidal geometry around the Cu(II) center, whereas complex 2 adopts a distorted square-pyramidal geometry. The nitrogen atoms of the amino groups remain uncoordinated in both complexes. The free ligand and its copper(II) complexes were evaluated as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors. The free H₂dpzpda ligand exhibited IC₅₀ values of 9.83 and 50.72 µM against AChE and BChE, respectively. Complexes 1 and 2 displayed IC₅₀ values of 5.50 and 1.42 µM against AChE and 41.30 and 25.68 µM against BChE, respectively. Comparison with the free ligand demonstrated that Cu(II) coordination enhanced cholinesterase inhibitory activity, particularly for complex 2 against AChE. Molecular docking and molecular dynamics simulations were also performed for both complexes against the two enzymes. In addition to single-crystal X-ray diffraction analyses, Hirshfeld surface analysis and two-dimensional fingerprint plots were employed to investigate the intermolecular interactions within the crystal structures. Furthermore, DFT calculations revealed HOMO–LUMO energy gaps of 3.70 and 0.79 eV for complexes 1 and 2, respectively. The markedly smaller energy gap of complex 2 indicated greater frontier-orbital delocalization and a higher tendency toward electronic transitions, while the molecular electrostatic potential maps identified the chloride, nitrate oxygen, and pyrazine nitrogen atoms as the principal electron-rich regions. These theoretical findings supported the structural and electronic features observed experimentally.

Photocatalytic degradation under ultraviolet irradiation provides an efficient strategy for removing toxic organic dyes such as Methylene Blue (MB) and Rhodamine B (RhB), which pose serious risks to aquatic ecosystems and human health. Copper-based photocatalysts are attractive alternatives to noble metals due to copper’s natural abundance, low cost, and accessible redox states. In this study, a mononuclear copper(II) complex, Cu(II)(2,9-dmp)Cl₂, was investigated as a homogeneous photocatalyst for MB and RhB degradation under UVC irradiation. The complex was characterised via CHN elemental analysis, FTIR, UV-Vis spectroscopy, and single-crystal X-ray diffraction (SCXRD), which confirmed a distorted square pyramidal geometry (τ = 0.26) within a monoclinic crystal system (space group P2₁). Photocatalytic performance was evaluated in a custom-built reactor (22 W UVC), with degradation kinetics assessed across varying dye concentrations, catalyst dosages, and H₂O₂ levels. Under optimal conditions, the catalyst achieved degradation efficiencies of 95% for MB and 90% for RhB within 100 min, following second-order kinetics. The higher rate constant for MB (0.242 M⁻¹min⁻¹) compared to RhB is tentatively attributed to the greater structural susceptibility of the thiazine framework relative to RhB’s rigid xanthene core. The complex is proposed to operate via a dual-pathway mechanism involving ligand-to-metal charge transfer (LMCT) and Cu(II)/Cu(I) redox cycling to generate hydroxyl radicals, although direct radical-identification experiments remain to be performed. These findings establish phenanthroline-based copper complexes as cost-effective, environmentally compatible photocatalysts, providing a foundation for future structural optimisation and heterogeneous system development for industrial wastewater treatment.

A new amine-templated cobalt(II) bis(phthalate) coordination polymer, ({H₃N(CH₂)₄NH₃}[Co(OOC–C₆H₄–COO)₂])ₙ (1), was synthesised by a conventional solution method using 1,4-diaminobutane as a structure-directing agent. Crystallographic studies reveal that the doubly deprotonated 1,2-benzenedicarboxylate (1,2-BDC^2-) ligands bridge adjacent Co(II) centres through their carboxylate groups, generating repeated 14-membered cyclic units that extend into a one-dimensional anionic helical chain. 1,4-diammoniobutane occupies the interchain regions, where it serves as a charge-balancing species and a supramolecular template. Coulombic interactions, extensive N–H···O hydrogen bonding, and complementary weak intermolecular interactions act cooperatively to organise the crystal packing, assembling adjacent polymeric chains into a three-dimensional supramolecular network. Antimicrobial investigations demonstrated that the coordination polymer exhibits promising activity against selected microbial strains. The present study highlights the effectiveness of amine-templating strategies in constructing structurally intriguing cobalt(II)-based coordination polymers with potential biological applications.

The lattice thermal conductivity of transition metals is fundamental to their applications in thermal management, high-temperature alloys, and energy-related technologies, as well as to understanding their lattice dynamics and heat-transport behavior. However, reliable and accurate prediction of thermal conductivity remains challenging due to anharmonic lattice effects, complex structure-property relationships, and limited experimental data. This study aims to predict the thermal conductivity of transition metals using a dataset of nearly 1000 individual records that include their physical and chemical properties, with the goal of designing advanced materials. To achieve the goal, this study employed several Gaussian Process Regression (GPR)-based models: Rational Quadratic GPR (RQGPR), Squared Exponential GPR (SEGPR), Matern 5/2 GPR (MGPR), Exponential GPR (EGPR), and Optimizable GPR (OGPR), which were investigated on the transition metals dataset. Among the implemented models, the OGPR showed excellent predictive performance, achieving R² values of 98.47% and 99.89% in the validation and tests for thermal conductivity prediction, respectively. Furthermore, the RReliefF algorithm is employed to reveal the significance of input features to the target property. Moreover, there is a strong relationship between the target attribute and the input feature that has the greatest influence. Furthermore, the partial dependence plots are also employed to interpret feature influence and validate model predictions. These findings demonstrate the effectiveness of machine-learning GPR models in predicting the thermophysical properties of transition metals.

Water pollution, driven by industrial, agricultural, and domestic activities, has introduced a diverse range of toxic contaminants into aquatic ecosystems, including heavy metals, dyes, pesticides, pharmaceuticals, endocrine-disrupting compounds, and volatile organic compounds (VOCs). Addressing these pollutants requires advanced, sustainable, and energy-efficient treatment technologies. This review critically examines recent advances in the application of metal oxide nanoparticles (MONPs) as photocatalysts for water remediation, with photocatalysis discussed as a key advanced oxidation process (AOP). The review highlights that engineered MONPs exhibit excellent photocatalytic performance, with many studies reporting degradation efficiencies exceeding 90% for a broad spectrum of organic pollutants under optimized conditions. Key findings demonstrate that band gap engineering, elemental doping, and morphology control significantly enhance visible-light absorption, improve charge separation, and increase reactive oxygen species (ROS) generation, thereby enabling efficient solar-driven photocatalysis. The review further discusses synthesis methods, characterization techniques, and the influence of operational parameters, including pH, pollutant concentration, catalyst dosage, light source, and co-existing ions and natural organic matter, on photocatalytic efficiency. Collectively, the reviewed studies identify band gap modulation and surface engineering as critical strategies for improving catalyst performance while emphasizing catalyst stability, reusability, and scalability as major challenges for practical implementation. Overall, this review provides a comprehensive assessment of current progress, identifies key knowledge gaps, and outlines future research directions toward the development of efficient, eco-friendly, and commercially viable MONP-based photocatalytic systems for sustainable water remediation.

In this work structural, mechanical, electronic, thermal, and piezoelectric characteristics of cubic KMF₃ fluoroperovskites (FP’s) (M = Fe, Co, Ni, Zn) treated under pressure 0–60 GPa has been presented by utilising density functional theory (DFT). All studied materials satisfied the stability tests which include structural optimizations, enthalpy of formation, Born–Huang mechanical stability conditions and Gold Schmidt tolerance factor. In mechanical analysis it is found that KNiF₃ attains the highest stiffness and hardness within the series, whereas KZnF₃ displays the most pronounced ductility and elastic anisotropy. In thermal analysis, Debye temperature, Grüneisen parameter, acoustic velocities, and minimum thermal conductivity demonstrates linear response with increase in pressure. Moreover in electronic properties, KZnF₃ found as a non-magnetic wide-gap semiconductor (Eᴳ = 3.80 eV at ambient pressure, increasing to 4.90 eV at 60 GPa). While all remaining magnetic materials KNiF₃, KCoF₃, and KFeF₃ are half-metallic at zero pressure and acquire fully metallic character upon compression at 60 GPa. Piezoelectric performance, assessed through the shear-to-bulk ratio (η), Kleinman parameter (ζ), and a composite figure-of-merit (FOM), places KCoF₃ as the most active ambient-pressure piezoelectric (FOM = 0.095) and KNiF₃ as the compound whose piezoelectric response is most strongly pressure-activated (58% FOM gain over 0–-60 GPa). This comprehensive analysis indicates that KMF₃ fluoroperovskites have strong potential as multifunctional materials for high-pressure applications.

A chiral Cu(II)–L-arginine Schiff base self-assembles into a one-dimensional helical coordination polymer. Hirshfeld surface analysis shows that O···H hydrogen bonding controls the supramolecular structure. UV–Vis and circular dichroism studies confirm effective transfer of molecular chirality into the extended coordination framework.

Copper electrodeposition on a glassy carbon electrode from a 70:30 (v/v) acetonitrile/water (AN/H₂O) electrolyte containing 0.01 M CuCl₂ and 0.5 M NaClO₄ as the background electrolyte was investigated in the absence and presence of 10^–3 M sodium dodecyl sulfate (SDS), tetrabutylammonium chloride (TBACl), and betaine hydrochloride ([Hbet]Cl) to elucidate the additive-dependent electrocrystallization in a mixed-solvent medium. Potentiostatic current-time transients recorded at − 0.45 V vs. Ag|AgCl were evaluated within the Scharifker-Hills (SH) framework to assess nucleation regimes and further analyzed using Scharifker-Mostany (SM) model to obtain the apparent nucleation descriptors A and N₀. The additive-free and SDS-containing electrolytes exhibited predominantly progressive-like 3D nucleation, whereas the TBACl and [Hbet]Cl responses lay between the progressive and instantaneous limits, with [Hbet]Cl showing a shift toward the instantaneous limit. TBACl yielded the highest SM-derived A and N₀ values, corresponding to the strongest apparent early-stage nucleation response among the investigated systems. The apparent double-layer capacitance (C_dl) of the resulting Cu/GC composite electrodes, measured by cyclic voltammetry in an aqueous 0.5 M NaHCO₃ solution, followed the order TBACl > SDS > [Hbet]Cl > additive-free sample. Scanning electron microscopy (SEM) provided complementary qualitative information on the final deposit morphologies within the examined regions, from sparsely distributed faceted crystallites in the additive-free electrolyte to closely spaced particulate deposits with TBACl and flower-/rosette-like crystallites with [Hbet]Cl and SDS. Overall, the results show additive-dependent differences in early-stage nucleation behaviour, apparent Cu/GC capacitive response, and final deposit morphology, providing a basis for future direct evaluation of the resulting Cu/GC electrodes in CO₂ electroreduction.

This work presents a combined experimental and theoretical study of the molecular structure, vibrational, and optical properties of tris(1,8-octanediammonium) bis(tetrachloridocobaltate) dichloride (C₈H₂₂N₂)₃(CoCl₄)₂Cl₂. The crystal structure consists of discrete [CoCl₄]²⁻ anions surrounded by organic (C₈H₂₂N₂)²⁺ cations and uncoordinated Cl⁻ ions, resulting in a zero-dimensional structure. Optical properties were investigated using UV–visible absorption and photoluminescence (PL) spectroscopy at room temperature. The UV–visible absorption spectrum exhibits an absorption edge near 280 nm, corresponding to an optical band gap of 4.42 eV. The PL spectrum shows a strong blue-green emission centered at 470 nm (2.63 eV). Additional characterization was performed using Raman and infrared spectroscopy at room temperature. For reliable assignment of vibrational modes, the IR and Raman spectra were calculated using density functional theory (DFT) at the B3LYP/LanL2DZ level. To gain deeper insight into the electronic structure, DFT and time-dependent DFT (TD-DFT) calculations were carried out, enabling evaluation of the density of states (DOS) and estimation of the band gap. The theoretical results show good agreement with the experimental observations, as evidenced by the close correspondence between calculated and measured absorption spectra. These results demonstrate that the optical properties arise from a synergistic interplay between the inorganic [CoCl₄]²⁻ units and the organic sublattice. In addition to offering a less toxic alternative to lead-based systems, this material shows promising potential for optoelectronic and photonic applications.

Two new hetero-metallic trinuclear copper(II)-Zinc(II) complexes; [(CuL¹)₂Zn(NCO)₂] (1) and [(CuL²)₂Zn(NCO)₂] (2) have been isolated by mixing two similar metalloligands [CuL¹] or [CuL²] (where H₂L¹= N, N’-bis(salicylidene)-1,3-propanediamine and H₂L² = N, N′-bis(α-methylsalicylidene)-1,3-propanediamine) separately with Zn(ClO₄)₂·6H₂O and NaOCN at same reaction condition. The trinuclear complexes have been structurally characterized by single crystal X-ray analyses showing that the molecular shape of 1 is bent whereas 2 is a triangular. In 1, the zinc is six-coordinate, being bonded to four oxygen atoms from two [CuL¹] units and a couple of cyanate nitrogen atoms. The geometry around Zn(II) is far from ideal octahedron. The coordination environments around copper centres are square planar with different degrees of tetrahedral distortions. On the other hand, Zn(II) is being bonded to only two phenoxido oxygens along with two cyanate nitrogen atoms and it is now distorted tetrahedral in 2. Interestingly, Cu(II) ions involve in axial interactions via double µ₃-phenoxido bridges with phenoxido oxygens that not bonded to Zn(II). As a result, they are now in a penta-coordinated square pyramidal environment.

Graphical abstract

Two new trinuclear hetero-metallic Cu(II)-Zn(II) compounds with different molecular shapes have been isolated by reacting two similar metalloligand with zinc perchlorate and sodium cyanate. Both the compounds have been characterized by elemental analysis, IR spectroscopy and single crystal X-ray crystallography