Cyclization of Alkyne–Azide with Isonitrile/CO via Self-Relay Rhodium Catalysis

A self-relay rhodium­(I)-catalyzed cyclization of alkyne–azides with two σ-donor/π-acceptor ligands (isonitriles and CO) to form sequentially multiple-fused heterocycle systems via tandem nitrene transformation and aza-Pauson–Khand cyclization has been developed. In this approach, an intriguing chemoselective insertion process of isonitriles superior to CO was observed. This reaction provides an alternative strategy to synthesize functionalized pyrrolo­[2,3-<i>b</i>]­indole scaffolds

Electronic Control of Traditional Iron–Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification

Shifting four-electron (4e–) oxygen reduction in fuel cell technology to a two-electron (2e–) pathway with traditional iron–carbon electrodes is a critical step for hydroxyl radical (HO•) generation. Here, we fabricated iron–carbon aerogels with desired dimensions (e.g., 40 cm × 40 cm) as working electrodes containing atomic Fe sites and Fe3C subnanoclusters. Electron-donating Fe3C provides electrons to FeN4 through long-range activation for achieving the ideal electronic configuration, thereby optimizing the binding energy of the *OOH intermediate. With an iron–carbon aerogel benefiting from finely tuned electronic density, the selectivity of 2e– oxygen reduction increased from 10 to 90%. The resultant electrode exhibited unexpectedly efficient HO• production and fast elimination of organics. Notably, the kinetic constant kM for sulfamethoxazole (SMX) removal is 60 times higher than that in a traditional iron–carbon electrode. A flow-through pilot device with the iron–carbon aerogel (SA-Fe0.4NCA) was built to scale up micropolluted water decontamination. The initial total organic carbon (TOC) value of micropolluted water was 4.02 mg L–1, and it declined and maintained at 2.14 mg L–1, meeting the standards for drinking water quality in China. Meanwhile, the generation of emerging aromatic nitrogenous disinfection byproducts (chlorophenylacetonitriles) declined by 99.2%, satisfying the public safety of domestic water. This work provides guidance for developing electrochemical technologies to satisfy the flexible and economic demand for water purification, especially in water-scarce areas

Pyridyl-imidazole copper compounds

Three 4-(2’-pyridyl)imidazole (4-pyim) complexes of copper(II) have been synthesized and studied structurally and magnetically. The structures of [CuCl2(4-pyim)] (1), [CuCl(4-pyim)2]2Cl2(H2O)10 (2), and [Cu(CuCl4)(4-pyim)2][Cu(H2O)(4-pyim)2](CuCl4)(H2O)4 (3) are reported. Single-crystal X-ray diffraction measurements show that 1 crystallizes in the monoclinic space group P21/n with a four-coordinate Cu(II) ion forming dimers via semi-coordinate bonds to bridging chloride ions. The structure of 1 shows the copper and chloride ions disordered over two sites. Compound 2 crystallizes in the triclinic space group P – 1 with five-coordinate Cu(II) ions in a highly distorted geometry between square pyramidal and trigonal bipyramidal. It has an extensive hydrogen bonding network created by 10 lattice water molecules, chloride ions, and nitrogen atoms in the ligands. Compound 3 crystallizes in the monoclinic space group Cc with both four- and five-coordinate Cu(II) ions present in the lattice; the five-coordinate Cu(II) ions display highly distorted geometries. All three compounds have hydrogen bonding and π-stacking interactions among the 4-pyim rings. Magnetic susceptibility data were collected on 1. Magnetic susceptibility data of 1 shows that it exhibits modest antiferromagnetic interactions which are best fit using a honeycomb model [(2J = −2.6(2) K), 2J’ = −1.6(2) K, H=−2J∑si·sj]. Disorder in the crystal structure decreases the rate of growth of the correlation length at low temperatures, lowering the temperature of the expected maximum in χ below the range of the data.</p

High-Yield Method To Fabricate and Functionalize DNA Nanoparticles from the Products of Rolling Circle Amplification

DNA condensation is a facile method to construct DNA nanostructure with a high biostability and low cost, which is mainly used in DNA separation and gene transfection. The recent emerging condensed DNA nanostructures from the rolling circle amplification (RCA), i.e., the complexes between RCA products and magnesium pyrophosphate (RCA–MgPPi), have quickly become attractive biomedical materials with broad application potential because they combine the advantages of the designable and high-throughput isothermal amplification technique and the high stability of DNA condensation structures. However, we find that only approximately 10% of RCA products can be condensed after an RCA reaction, which limits the practical application of the RCA–MgPPi nanostructures. Therefore, in this paper, we investigate how to control the condensation efficiency of RCA-synthesized DNAs in depth. The very long RCA products, which show high charge densities, can be efficiently condensed by an excessive amount of Mg²⁺ to form RCA–MgPPi nanostructures at a yield approaching 100%. Additionally, the new condensation approach is general and is not limited to the RCA products, which can be applied to other polymeric DNAs. These RCA–MgPPi nanoparticles exhibit a high biostability and low toxicity, in addition, which can be efficiently functionalized with foreign components to create hierarchical properties. Finally, as a proof of concept, based on RCA–MgPPi nanostructures, a ratiometric fluorescence sensor system has been constructed and demonstrated to be an efficient lysosomal pH tracker

Enhancing Doxorubicin Delivery toward Tumor by Hydroxyethyl Starch‑<i>g</i>‑Polylactide Partner Nanocarriers

Doxorubicin (DOX), a kind of wide-spectrum chemotherapeutic drug, can cause severe side effects in clinical use. To enhance its antitumor efficacy while reducing the side effects, two kinds of nanoparticles with desirable compositions and properties were assembled using optimally synthesized hydroxyethyl starch-grafted-polylactide (HES-<i>g</i>-PLA) copolymers and utilized as partner nanocarriers. The large empty HES-<i>g</i>-PLA nanoparticles (mean size, <i>ca.</i> 700 nm), at an optimized dose of 400 mg/kg, were used to block up the reticuloendothelial system in tumor-bearing mice 1.5 h in advance, and the small DOX-loaded HES-<i>g</i>-PLA nanoparticles (mean size, <i>ca.</i> 130 nm) were subsequently applied to the mice. When these partner nanocarriers were administered in this sequential mode, the released DOX had a significantly prolonged plasma half-life time and much slower clearance rate as well as a largely enhanced intratumoral accumulation as compared to free DOX. <i>In vivo</i> antitumor studies demonstrated that the DOX-loaded HES-<i>g</i>-PLA nanoparticles working together with their partner exhibited remarkably enhanced antitumor efficacy in comparison to free DOX. In addition, these HES-<i>g</i>-PLA partner nanocarriers showed negligible damage to the normal organs of the treated mice. Considering safe and efficient antitumor performance of DOX-loaded HES-<i>g</i>-PLA nanoparticles, the newly developed partner nanocarriers in combination with their administration mode have promising potential in clinical cancer chemotherapy

Magnetic Structure and Exchange Interactions in Quasi-One-Dimensional MnCl₂(urea)₂

MnCl₂(urea)₂ is a new linear chain coordination polymer that exhibits slightly counter-rotated Mn₂Cl₂ rhomboids along the chain-axis. The material crystallizes in the noncentrosymmetric orthorhombic space group <i>Iba</i>2, with each Mn­(II) ion equatorially surrounded by four Cl^– that lead to bibridged ribbons. Urea ligands coordinate via O atoms in the axial positions. Hydrogen bonds of the Cl···H–N and O···H–N type link the chains into a quasi-3D network. Magnetic susceptibility data reveal a broad maximum at 9 K that is consistent with short-range magnetic order. Pulsed-field magnetization measurements conducted at 0.6 K show that a fully polarized magnetic state is achieved at <i>B</i>_sat = 19.6 T with another field-induced phase transition occurring at 2.8 T. Zero-field neutron diffraction studies made on a powdered sample of MnCl₂(urea)₂ reveal that long-range magnetic order occurs below <i>T</i>_N = 3.2(1) K. Additional Bragg peaks due to antiferromagnetic (AFM) ordering can be indexed according to the <i>Ib</i>′<i>a</i>2′ magnetic space group and propagation vector τ = [0, 0, 0]. Rietveld profile analysis of these data revealed a Néel-type collinear ordering of Mn­(II) ions with an ordered magnetic moment of 4.06(6) μ_B (5 μ_B is expected for isotropic <i>S</i> = ⁵/₂) oriented along the <i>b</i>-axis, i.e., perpendicular to the chain-axis that runs along the <i>c</i>-direction. Owing to the potential for spatial exchange anisotropy and the pitfalls in modeling bulk magnetic data, we analyzed inelastic neutron scattering data to retrieve the exchange constants: <i>J</i>_c = 2.22 K (intrachain), <i>J</i>_a = −0.10 K (interchain), and <i>D</i> = −0.14 K with <i>J</i> > 0 assigned to AFM coupling. This <i>J</i> configuration is most unusual and contrasts the more commonly observed AFM interchain coupling of 1D chains

Epitaxial Growth of Multimetallic Pd@PtM (M = Ni, Rh, Ru) Core–Shell Nanoplates Realized by in Situ-Produced CO from Interfacial Catalytic Reactions

Pt-based multimetallic core–shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core–shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core–shell, and alloy structures

Antiferromagnetism in a Family of <i>S</i> = 1 Square Lattice Coordination Polymers NiX₂(pyz)₂ (X = Cl, Br, I, NCS; pyz = Pyrazine)

The crystal structures of Ni<i>X</i>₂(pyz)₂ (X = Cl (<b>1</b>), Br (<b>2</b>), I (<b>3</b>), and NCS (<b>4</b>)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN₄<i>X</i>₂ units that are bridged by pyz ligands. The 2D layered motifs displayed by <b>1</b>–<b>4</b> are relevant to bifluoride-bridged [Ni­(HF₂)(pyz)₂]­<i>E</i>F₆ (<i>E</i> = P, Sb), which also possess the same 2D layers. In contrast, terminal <i>X</i> ligands occupy axial positions in <b>1</b>–<b>4</b> and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and <i>g</i> factor of <b>2</b>, <b>3</b>, and <b>4</b> were measured by electron-spin resonance with no evidence for zero–field splitting (ZFS) being observed. The magnetism of <b>1</b>–<b>4</b> spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for <b>2</b> and <b>4</b> as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for <b>2</b> and <b>4</b> calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound <b>3</b> is characterized as a 3D AFM with the interlayer interaction (<i>J</i>_⊥) being slightly stronger than the intralayer interaction along Ni–pyz–Ni segments (<i>J</i>_pyz) within the two-dimensional [Ni­(pyz)₂]²⁺ square planes. Regardless of <i>X</i>, <i>J</i>_pyz is similar for the four compounds and is roughly 1 K