Chemistry - An Asian Journal最新文献

We report a bora(amino)silylene-coordinated copper metallacycle [{LSi(NDipp(BPin))-Cu-Si(N^tBuC(H)PhN^tBu)(NDipp(BPin))}] (2) (L = PhC(N^tBu)₂). Complex 2 was isolated during attempts to prepare a silylene-coordinated copper hydride. Reaction of a (bis)silylene-copper-tert-butoxide intermediate with pinacolborane resulted in the ligand transformation via B─H bond activation and the transfer of a hydrogen atom to the ligand backbone. The complex 2 was characterized by multinuclear NMR spectroscopy and single-crystal x-ray diffraction studies. Preliminary theoretical calculations were performed to suggest a possible reaction pathway for the formation of complex 2.

Synthesis of a robust redox metal oxide based material with nanoscale porosity is very demanding in the context of heterogeneous catalysis. Hereby, we report a convenient synthetic approach for designing hierarchically porous Mn₃O₄ nanocrystals (HP-Mn₃O₄-NCs) using a small organic molecular entity, sodium salicylate, as a structure-directing agent. The porosity and the crystallinity were evaluated through the powder XRD, TEM, and N₂ sorption. TEM analysis revealed the presence of mesopores, which agrees well with the N₂ sorption analysis. XPS analysis revealed the presence of a mixed-valent Mn²⁺ and Mn³⁺. The aerial dehydrogenative C─N cross-coupling of aromatic diamines and alcohols for the selective production of benzimidazole derivatives proceeds smoothly in the presence of HP-Mn₃O₄-NCs as a heterogeneous catalyst. The catalyst displayed a clean reaction profile with excellent product yields of up to 94% for various substrates. Noticeably, the reaction is accomplished under base-free, solvent-free, and aerial conditions. The existence of mesopore enables a high internal surface area, thereby increasing the exposure of surface-active sites. The mesopores of the material promote the facile diffusion of reactants and products. Large specific surface area, abundant surface-active sites, stability, and structural robustness collectively endow the HP-Mn₃O₄-NCs with high catalytic activity and recycling efficiency.

In this study, we report a metal- and photocatalyst-free protocol for synthesizing (E)-β-amidovinyl sulfones under visible light via an electron donor–acceptor (EDA) complex formed between thiosulfonates and DMAP in DMSO. This method offers a mild, efficient, and cost-effective approach to access β-amidovinyl sulfones from enamides with E-selectivity and excellent functional group tolerance.

An oxidation-phosphorization route was adopted to prepare cobalt phosphide supported on nitrogen-doped biochar (denoted as CoP/NBC) for ammonia borane hydrolysis. NBC (i.e., nitrogen-doped biochar) was obtained by NH₄Cl-assisted pyrolysis of paulownia wood and used to disperse Co species. After in situ reduction, controlled oxidation, and low-temperature phosphorization, CoP nanosheets were formed on the porous biochar support. The optimized CoP/NBC catalyst displayed a turnover frequency (TOF) of 47 mol_H2∙mol_Co⁻¹∙min⁻¹ at 303 K, and the catalyst had no significant loss of activity over five consecutive cycles. Structural characterization confirmed the formation of crystalline CoP and suggested interfacial electronic interactions between CoP and NBC. The porous N-doped biochar support favored the dispersion of CoP and facilitated mass transfer, while phosphorization modified the electronic state of Co. These combined structural features contributed to the catalytic performance of CoP/NBC and provide a simple strategy for developing low-cost non-noble-metal catalysts for hydrogen generation from ammonia borane.

P(St-AM)-based Cu species (Cu, Cu₂O, CuO) composite microspheres have been successfully prepared by a photochemical construction technology at room temperature. The process involved the photochemical synthesis of P(St-AM) microspheres and the following deposition of Cu species nanoparticles on the surface of P(St-AM) microspheres under the irradiation of 365 nm and 254 nm UV lamps, respectively. The as-obtained composite microspheres were characterized by SEM, XRD, FTIR, DSC, and BET analyses. The as-prepared P(St-AM)-Cu-1 which has the minimum loading amount of Cu species nanoparticles was chosen as the typical adsorbent, and methyl orange was selected as a representative dye containing sulfonic groups. The adsorption capacity reached a maximum of 125.5 mg g⁻¹ at methyl orange concentration of 276.0 mg L⁻¹. The pseudo-second order kinetic model and Langmuir isotherm model described the adsorption behavior. The higher correlation coefficient (R²) and smaller values of error functions (χ², root-mean-square error) validated applicability of both the models. The composite microspheres demonstrated excellent cyclic stability. This work presents a promising photochemical strategy for constructing polymer-metal composite adsorbents for dye adsorption.

The development of triboelectric materials is of great significance for the construction of self-powered systems. In this work, a host-guest type material was constructed by introducing Hg²⁺ ions functionally into the pores of metal–organic frameworks through a post-synthesis modification strategy, and it was applied in triboelectric nanogenerators. The results showed that compared with the pure MOF, Zn-MOF(Hg) significantly improved the output performance, with the short-circuit current increasing from 39.7 µA to 52.3 µA and the power density reaching 3317.76 mW/m². This phenomenon was mainly attributed to the fact that Hg²⁺ could act as an efficient charge capture center, inhibiting charge recombination during the friction process, thereby enhancing the output performance. Density functional theory results also indicated that Hg²⁺ ions could increase the highest occupied molecular orbital energy level and reduce the band gap, thereby lowering the energy barrier for electron transition. By constructing a harmful antibiotic degradation system with Zn-MOF(Hg)@TENG, the chloramphenicol degradation rate reached over 98% within 150 min. Moreover, the stable output of Zn-MOF(Hg)@TENG can also easily light up LED lamp groups and other electronic devices. This work provides new ideas for the development of frictional electrochemical materials and the resource utilization of heavy metal ions.

In this study, a Lasoda hydrogel-based composite incorporating hydroxyl-functionalized graphene oxide (LA-GO-OH) was developed for efficient adsorption of polycyclic aromatic hydrocarbons (PAHs) from aqueous media. Hydroxyl-functionalized graphene oxide (GO) was synthesized via a thermal shock method and integrated into the Lasoda hydrogel through in situ polymerization. Structural and surface characterization using FESEM, EDS, XRD, FTIR, Raman, and XPS confirmed successful composite formation, preservation of hydroxyl functionalities, and graphitic domains. XPS analysis of the composite after adsorption of naphthalene (Nap) and anthracene (Ant) revealed characteristic C 1s binding energies (∼284.78 eV) corresponding to sp²-hybridized aromatic carbon, along with π→π* shake-up satellite features (∼286–289 eV), indicating intact aromatic structures after adsorption. Ant exhibited stronger satellite features than Nap due to greater electronic delocalization. Adsorption studies monitored by UV-visible spectroscopy at λ_max values of 220 nm (Nap) and 375 nm (Ant) demonstrated maximum removal efficiencies of 97% and 94%, with adsorption capacities of 88 and 128 mg g⁻¹, respectively. Adsorption mainly occurred through π–π interactions between aromatic molecules and graphitic domains. Equilibrium data followed the Langmuir isotherm, kinetics obeyed the pseudo-second-order model (R² = 0.99), and thermodynamic analysis confirmed spontaneous, endothermic, and entropy-driven adsorption.

Hydrogen is a key energy vector in the shift toward carbon-neutral energy systems, such as the global hydrogen economy. Of the possible production pathways, catalytic water splitting (photocatalytic, electrocatalytic, and thermos-catalytic) has drawn particular attention for its potential in producing green hydrogen. Recently, framework materials such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs) have shown enormous potential as precisely tunable catalytic platforms due to their large surface areas, structural flexibility, and tunable electronic properties. Here, we review MOFs, COFs and HOFs for hydrogen production applications, with a focus on structure–property–performance relationships. MOFs provide a range of metal active sites and porosity, but have low conductivity and low stability in water. COFs, thanks to their extended π-conjugation and strong covalent bonds, have better charge mobility and visible-light absorption, making them promising photocatalysts. While less studied, HOFs offer benefits in terms of their easy preparation and reversible structure but suffer from weak intermolecular forces. We explore the advances in band gap engineering, heterojunction formation, cocatalysts, and defect engineering, in terms of key performance indicators of catalytic activity, including turnover frequency (TOF), quantum efficiency, and overpotential. Finally, key issues such as stability, scalability, and standardization, and emerging trends, including machine learning-aided discovery of materials and integrated solar hydrogen systems, are assessed. Of the three types, COFs and MOF-derived catalysts hold the most promise for scalable green hydrogen generation.

A Co(III) complex is synthesized with a redox-active N-heterocyclic carbene (NHC) ligand, and the structure of this complex is established by single-crystal XRD. This bimetallic Fe^Fe^Co complex was explored in an alkene oxidation reaction to give aldehydes as products, which could be accomplished via water oxidation catalysis at room temperature. In the proposed mechanism, both metal-ligand cooperativity as well as bimetallic participation of the two metals Co and Fe (of one unit of ferrocene moiety) further facilitates the two oxidation cycles altogether. The peroxo intermediate in the catalytic water oxidation cycle is proposed to be the crucial intermediate species for the conversion of the unsaturated system into its corresponding aldehydes.