The Royal Society of Chemistry最新文献

Tris(2-pyrimidyl)- and tris(5-pyrimidyl)phosphines, previously inaccessible multidentate ligands, have been synthesized and introduced into coordination chemistry. Theoretical studies indicate that both ligands are weak σ-donors and strong π-acceptors, exhibiting electronic properties comparable to those of trialkyl phosphites. Positional isomerism of the pyrimidyl groups induces a pronounced difference in steric profile, with the 5-isomer adopting a more open conformation and the 2-isomer a significantly more compact geometry, reflected in their Tolman cone angles of 157° and 148°, respectively. Reactions with Cu(I), Cu(II), Ag(I), Au(I), Co(II), and Pt(II) salts afforded a series of molecular complexes together with 1D and 2D coordination polymers. Tris(5-pyrimidyl)phosphine acts predominantly as a P-monodentate or P,N-/N,N'-bridging ligand, yielding extended frameworks, whereas tris(2-pyrimidyl)phosphine forms both discrete complexes and coordination polymers through P,N,N'- and P,N,N',N″-modes. Selected Cu(I) and Ag(I) complexes exhibit short-lived luminescence with emission maxima between 460 and 605 nm. These findings demonstrate the potential of symmetric tris(pyrimidyl)phosphines as versatile ligands for coordination chemistry.

With the aim of investigating whether the coordination of fenamates to Ni(II) affects the biological profile, a chloro-derivative of fenamic acid (4'-chloro-fenamic acid) was synthesized and used as a ligand for the synthesis of seven nickel(II) complexes in the absence or presence of the nitrogen-donors pyridine, β-picoline, 1H-imidazole, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, and 2,2'-bipyridylamine. The characterization of the resultant Ni(II) complexes was performed with diverse techniques (elemental analysis, molar conductivity measurements, mass spectrometry, IR and UV-vis spectroscopy, and single-crystal X-ray crystallography). The compounds were evaluated for their in vitro biological activity in terms of the antioxidant activity via free radical scavenging and H₂O₂ reduction, the antimicrobial activity against two Gram-positive and two Gram-negative bacterial strains, the interaction with calf-thymus DNA, the cleavage of supercoiled pBR322 plasmid DNA (pDNA) in the dark or under UVB/UVA/visible light irradiation, and the binding affinity toward bovine and human serum albumins. The antioxidant activity of the compounds is noteworthy against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals and H₂O₂, and comparable with that of the reference compounds. The complexes exhibit notable antimicrobial activity against the strains tested. The compounds interact with calf-thymus DNA via intercalation with binding constants of 10⁵-10⁶ M^-1 magnitude. The pDNA-cleavage ability of the compounds is significantly enhanced under irradiation. All the compounds can bind tightly and reversibly to both albumins tested.

The reactivity of the sodium phosphido-borane complex, [Na(THF)₃]⁺[1-BCy₂-8-PPh-C₁₀H₆]^- (1), with RCH₂NC isocyanides is reported. In contrast to traditional bases or phosphides, 1 act as an efficient nucleophile to form reactive carbanion intermediates instead of proton abstraction from RCH₂NC and formation of protonated phoshane 1-BCy₂-8-P(H)Ph-C₁₀H₆ (2). This study showed that 1 acts as a nucleophile and reacts with RCH₂NC in a 1 : 2 stoichiometry to form a 2-imidazoline, imidazole or an enamine. Isolated compounds demonstrate the ability of 1 in promoting carbanion formation and participating in subsequent reactions to give various N-substituted alkyl phosphine organic compounds, which are not usually obtained by different synthetical approaches.

In this study, a one-dimensional (1D) numerical simulation framework based on COMSOL Multiphysics was employed to investigate and optimize the structural design of a lead-free PSC. To optimize the device performance, the thickness of the ETL, absorber layer, and HTL was systematically varied, and its influence on the PV characteristics was investigated under standard operating conditions. Furthermore, the effects of operating temperature, donor concentration, and acceptor concentration on the electrical and PV behavior of the PSC were comprehensively examined. The simulation results demonstrated that the device performance was strongly influenced by both structural and material parameters. The highest PCE of approximately 19.565%, together with a P_max value of 195.650 W m^-2 and a J_sc value of 29.39 mA cm^-2, was achieved at an operating temperature of 285 K when the device temperature was varied between 285 K and 325 K. In addition, the maximum FF of 88.343% and a V_oc value of 1.012 V were obtained for a 50 nm-thick CsSnI₃ absorber layer. These findings highlight the critical role of optimizing layer thicknesses and operating conditions in augmenting the PV performance of lead-free PSCs. Overall, the present simulation offers valuable insights into the design and optimization of environmentally benign, low-cost, and lead-free PSCs. The optimized Mg-ZnO/CsSnI₃/GO device architecture demonstrates considerable potential for achieving high PV performance while addressing the toxicity concerns associated with lead-based perovskite materials.

The oxygen evolution reaction (OER) is a critical half-reaction in electrochemical energy conversion technology; however, its slow kinetic process limits energy conversion efficiency. Nickel iron layered double hydroxides (NiFe-LDHs) are promising OER electrocatalysts, which face challenges such as insufficient active centers and poor electron transfer ability. In this study, we report successful in situ doping of Cr ions on the surface of NiFe-LDH using a simple one-step hydrothermal method. The addition of Cr induced synergistic lattice and electronic effects, increased the active surface area and exposed more active sites, leading to excellent OER performance with a low overpotential of 219 mV at a current density of 100 mA cm^-2, a Tafel slope of 58.16 mV dec^-1, and long-term stability for 500 h in 1 M KOH. Cr³⁺ doping could adjust the coordination of Ni, Fe and O, optimize the adsorption of intermediates, accelerate electron transfer and enhance OER kinetics. This work provides a new idea for the regulation of the activity of NiFe-LDHs by heterovalent ion doping and offers a reference for low-cost and high-efficiency OER catalysts.

Smartphone-based colorimetric sensor arrays using natural dyes are promising for on-site meat freshness assessment, but varying illumination and imaging angles compromise reliability. To address this, we developed an anthocyanin-curcumin array incorporating an α-Fe₂O₃ internal standard and an internal-standard-guided dynamic feature-space switching (IS-DFSS) strategy and validated its effectiveness under complex imaging conditions using ammonia as the representative analyte because it is the dominant component of total volatile basic nitrogen (TVB-N). Eight colorimetric films and the internal standard film were hydrophobically modified and assembled into a 3 × 3 array. The water contact angle increased from 63.3° to 112.9°, ensuring signal stability in high humidity. The sensing units responded strongly to TVB-N components ammonia, trimethylamine (TMA), and dimethylamine (DMA). For ammonia, Euclidean distance increased from 1.23 to 24.7 at 50 ppm and 13.7 to 65.7 at 500 ppm over 120 min, while non-alkaline volatiles (ethanol, hexanal) and non-volatile food matrix components (protein, glucose, fat) were negligible. In pork at 4 °C, array response correlated with TVB-N content (R² = 0.987). The RGB values from 174 ammonia-responsive and 126 environment-interference images were averaged over three replicates to construct datasets, deriving HSV and Lab features. IS-DFSS with CatBoost reduced the mean absolute error to 15.85 ppm (45.46% reduction) and the mean false-signal error to 27.49 ppm (33.97% reduction) versus single RGB features, achieving R² = 0.972. This method provides a robust, portable platform for monitoring TVB-N components, laying the foundation for reliable meat freshness assessment under complex imaging conditions.

A theoretical model has been developed to describe the spin transformation in the [(Fe(RR-cth))(Co(SS-cth))(μ-dhbq)](AsF₆)₃ compound, accompanied by a change in macroscopic polarization caused by electron density redistribution due to reversible intramolecular electron transfer between the μ-dhbq ligand and Fe ion. In this model, the states of a single complex arising from its three configurations are accounted: low-spin-Fe³⁺-dhbq^3--low-spin-Co³⁺, high-spin-Fe³⁺-dhbq^3--low-spin-Co³⁺ and high-spin-Fe²⁺-dhbq^2--low-spin-Co³⁺. Due to the molecular structure of the compound demonstrating this transformation, the interaction between the molecular modes forming the spectrum of a single complex and the crystalline modes assuring cooperativity in the system is assumed to be responsible for the spin transformation. This model also includes the dipole-dipole interaction between complexes in the whole crystal responsible for electron density redistribution caused by electron transfer. The problem of interacting complexes is solved in the mean field approximation. On the basis of the developed model, a comprehensive explanation of the magnetic and polarization characteristics of the [(Fe(RR-cth))(Co(SS-cth))(μ-dhbq)](AsF₆)₃ compound is given. The inclusion of the intermediate excited configuration high-spin Fe³⁺-dhbq^3--low-spin-Co³⁺, along with the ground and final configurations of the FeCo dimeric complex in the model, allows for the explanation of the unusual increase in the macroscopic polarization observed after the low-spin → high-spin transition in the iron ion is completed.

Organisms biosynthesize square planar metal tetrapyrrole cofactors containing Mg, Fe, Co, and Ni using chelatase enzymes, which selectively insert the correct metal into a specific organic ligand. Archaeoglobus fulgidus CbiX^S has been proposed to be an "ancestral" chelatase enzyme; in this work we have evaluated its substrate scope to ascertain whether this enzyme is a promising starting point for synthetic chelatase design. Size-exclusion chromatography revealed that CbiX^S is a tetramer in solution regardless of the metalation state of the enzyme, in contrast to the dimeric structure of the nickel chelatase CfbA. Reaction conditions that minimize enzyme-free metal insertion into tetrapyrroles were determined, which revealed that many of the in vitro activity assays reported in the literature for chelatase enzymes may be plagued by non-enzymatic metal insertion. Under these conditions that minimize uncatalyzed metal insertion, CbiX^S was observed to catalyze metal insertion for six different combinations of metal and tetrapyrrole. Based upon the turnover numbers of these reactions, CbiX^S is most effective at catalyzing metal insertion for reactants similar to its native substrates: cobalt and sirohydrochlorin. Kinetic analysis for reactions with varying substrate concentrations revealed that CbiX^S may be substrate-inhibited for non-native substrates. In addition, the kinetic data identifies metal-ligand bond formation as the rate-limiting step of the enzyme. Due to its broad substrate scope, CbiX^S is an encouraging starting point for synthetic chelatase design that could yield non-natural metal tetrapyrroles for use in the biotechnology sector.

Dehydrogenation of Mg(BH₄)₂·THF_x (1·THF) at 180 °C has been previously found to produce primarily a mixture of Mg(B₃H₈)₂ (2) and Mg(B₁₀H₁₀) (3). It has now been found that dehydrogenation under a H₂ back pressure of 20 bar suppresses the formation of 2 and results in very high (>95%) selectivity for 3. The production of 3 is not inhibited by hydrogen pressure. This demonstrates that the reaction pathway leading to its formation does not involve reversible, rate limiting H₂ elimination and is divergent from the pathway leading to 2. Unlike the pathway leading to the formation of 2, the dehydrogenation of 1·THF to 3 is irreversible under moderate conditions. Concurrent with the dehydrogenation reaction, THF is slowly converted to Mg(OBu_n)₂, curtailing the production 3. However, the dehydrogenation process is revived by addition of a fresh aloquate of THF to the reaction mixtures. It is hypothesized that THF enables the production of 3 by stabilizing the key intermediate, [B₂H₅]^- and by the low melting point (<100 °C) of 1·THF which allows long-range diffusion of borane anions at much lower energies than those required for their transport in the solid-state.

Valence-to-core (VtC) X-ray emission spectroscopy (XES) is a powerful probe for the local electronic structure in transition-metal materials, but its potential for 4d metals such as zirconium remains largely unexplored. Here, we demonstrate that non-resonant Zr Kβ VtC XES provides quantitative descriptors that are sensitive to ligand chemistry, by probing fluorine- and oxygen-based coordination environments in well-defined and catalytically relevant Zr compounds. High-resolution X-ray emission spectra containing Zr-Kβ₂ and -Kβ₄ are recorded for a series of reference systems (ZrO₂, ZrF₄, ZrF₄·H₂O, ZrCl₄, Zr(acac)₄, Zr metal) and for Zr fluoride materials, and are analysed using quantitative line-shape parameters. Projected densities of states (PDOS) obtained from FDMNES calculations reveal that fluorine coordination enhances the Kβ″ contribution and induces characteristic changes in Kβ₂ intensity and asymmetry compared to oxygen and chlorine ligands. These ligand-specific spectral signatures enable a systematic discrimination between F- and O-containing coordination spheres, even when conventional X-ray absorption or diffraction techniques provide limited contrast. This combined experimental-computational framework demonstrates that Zr Kβ VtC XES can resolve subtle ligand-dependent coordination changes in Zr-based materials, offering a general route to identify active structures in C-F bond activation and oxygen-evolution catalysis.