Size Growth of Au₄Cu₄: From Increased Nucleation to Surface Capping

The size conversion of atomically precise metal nanoclusters is fundamental for elucidating structure-property correlations. In this study, copper salt (CuCl)-induced size growth from [Au4Cu4(Dppm)2(SAdm)5]+ (abbreviated as [Au4Cu4S5]+) to [Au4Cu6(Dppm)2(SAdm)4Cl3]+ (abbreviated as [Au4Cu6S4Cl3]+) (SAdmH = 1-adamantane mercaptan, Dppm = bis-(diphenylphosphino)methane) was investigated via experiments and density functional theory calculations. The [Au4Cu4S5]+ adopts a defective pentagonal bipyramid core structure with surface cavities, which could be easily filled with the sterically less hindered CuCl and CuSCy (i.e., core growth) (HSCy = cyclohexanethiol) but not the bulky CuSAdm. As long as the Au4Cu5 framework is formed, ligand exchange or size growth occurs easily. However, owing to the compact pentagonal bipyramid core structure, the latter growth mode occurs only for the surface-capped [Au4Cu6(Dppm)2(SAdm)4Cl3]+ structure (i.e., surface-capped size growth). A preliminary mechanistic study with density functional theory (DFT) calculations indicated that the overall conversion occurred via CuCl addition, core tautomerization, Cl migration, the second [CuCl] addition, and [CuCl]-[CuSR] exchange steps. And the [Au4Cu6(Dppm)2(SAdm)4Cl3]+ alloy nanocluster exhibits aggregation-induced emission (AIE) with an absolute luminescence quantum yield of 18.01% in the solid state. This work sheds light on the structural transformation of Au–Cu alloy nanoclusters induced by Cu(I) and contributes to the knowledge base of metal-ion-induced size conversion of metal nanoclusters

Dual-Functional WO₃ Nanocolumns with Broadband Antireflective and High-Performance Flexible Electrochromic Properties

The three-dimensional, high-porous, and oriented WO₃ nanocolumn film with broadband antireflective and high-performance flexible electrochromic dual-functionalities is achieved by utilizing a simple, one-step, room-temperature glancing angle deposition without any catalysts and templates. It is found that the WO₃ nanocolumn film is effective in increasing the optical transparency in the visible range, enhancing the color-switching response time as well as improving the mechanical flexibility and electrochemical cycling stability in comparison to dense WO₃ film. The further optical, morphological, and electrode reaction kinetics analyses reveal that these improvements can be attributed to its unique porous nanocolumn arrays, which reduce the refractive index, facilitate the interfacial charge-transfer and ion-penetration, and alleviate the internal stress of the film under the bending treatment. These results would provide a simple and effective guidance to design and construct low-cost, robust, flexible, stable, and transparent electrochromic smart windows

Synergistic H₄NI–AcOH Catalyzed Oxidation of the C_sp³–H Bonds of Benzylpyridines with Molecular Oxygen

The oxidation of benzylpyridines forming benzoylpyridines was achieved based on a synergistic H₄NI–AcOH catalyst and molecular oxygen in high yield under solvent-free conditions. This is the first nonmetallic catalytic system for this oxidation transformation using molecular oxygen as the oxidant. The catalytic system has a wide scope of substrates and excellent chemoselectivity, and this procedure can also be scaled up. The study of a preliminary reaction mechanism demonstrated that the oxidation of the C_sp³–H bonds of benzylpyridines was promoted by the pyridinium salts formed by AcOH and benzylpyridines. The synergistic effect of H₄NI–AcOH was also demonstrated by control experiments

Additional file 1: of The effects of local administration of mesenchymal stem cells on rat corneal allograft rejection

Figure S1. Differentiation potential of MSCs. (A)Morphology of bone marrow derived mesenchymal stem cells of Wistar rat. (B) Osteogenesis was observed by the formation of the matrix mineralization in Alizarin Red staining. (C) Adipogenesis was observed in MSCs by the formation of lipid droplets with Oil Red O staining. (TIF 8423 kb

Low-Work-Function, ITO-Free Transparent Cathodes for Inverted Polymer Solar Cells

A low-work-function, indium tin oxide (ITO)-free transparent cathode having a tin oxide (SnO_X)/Ag/SnO_X/bismuth oxide (Bi₂O₃) (SASB) structure is developed without using annealing treatment. This represents the first time that Bi₂O₃ has been introduced to lower the work function of transparent electrodes. The SASB transparent cathode exhibits excellent photoelectric properties with a maximum transmittance of ∼88%, a low sheet resistance of ∼9.0 Ω·sq^–1, and a suitable work function of 4.22 eV that matches the lowest unoccupied molecular orbital level of the acceptor for exacting electrons efficiently. The power conversion efficiency of the polymer solar cell with the SASB electrode is 6.21%, which is comparable to that of ITO-based devices. The results indicate that SASB is a good alternative to ITO as transparent cathodes in optoelectronic devices

Dissipation, terminal residue and dietary risk assessment of flonicamid in cabbage

To investigate the dissipation, terminal residues, and dietary exposure risk of flonicamid, a field trial was conducted in China, and cabbage samples were determined by modified QuEChERS pretreatment and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The method showed good linearity (R2 ≥ 0.99), the mean recoveries ranged from 97% to 103%, with the relative standard deviation (RSD) less than 1.5%, and the matrix effect (ME) was 5%. The field trial showed that the dissipation of flonicamid in Shanxi conformed to the first-order kinetic equation with a half-life of 2.2 days. The terminal residue results showed that the residues of flonicamid in cabbage were all lower than 0.12 mg/kg. The hazard quotient (HQ) and risk quotient (RQ) were applied to dietary exposure risk assessment based on terminal residue and toxicology data. The HQ of different populations ranged from 0.17 to 0.37, and the RQ was 81.4%, indicating low risk of dietary intake of flonicamid in cabbage.</p

An Effective Method for the Construction of Esters Using Cs₂CO₃ as Oxygen Source

An effective method for the construction of esters from acyl chloride and halohydrocarbon using Cs₂CO₃ as an oxygen source was achieved for the first time. The methodology has a wide scope of substrates and can be scaled up. The study of a preliminary reaction mechanism demonstrated that the O in the products comes from Cs₂CO₃ and this esterification proceeds through a free radical reaction. It was also found that CO₂ can also be used in this esterification reaction as an oxygen source

Selective Oxidation of Unsaturated Alcohols Catalyzed by Sodium Nitrite and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone with Molecular Oxygen under Mild Conditions

We have developed a simple and practical process for the oxidation of alcohols to the corresponding carbonyl compounds by using a low catalytic amount of DDQ, NaNO₂ as a cocatalyst, and molecular oxygen as terminal oxidant. Nitric oxide generated in situ by NaNO₂ in the presence of AcOH is essential for the realization of the catalytic cycle at room temperature. The practical utility of this catalytic process has been demonstrated in the gram-scale oxidation of cinnamyl alcohol

Highly Chemoselective and Enantioselective Catalytic Oxidation of Heteroaromatic Sulfides via High-Valent Manganese(IV)–Oxo Cation Radical Oxidizing Intermediates

A manganese complex with a porphyrin-like ligand that catalyzes the highly chemoselective and enantioselective oxidation of heteroaromatic sulfides, including imidazole, benzimidazole, indole, pyridine, pyrimidine, pyrazine, <i>sym</i>-triazine, thiophene, thiazole, benzothiazole, and benzoxazole, with hydrogen peroxide is described, furnishing the corresponding sulfoxides in good to excellent yields and enantioselectivities (up to 90% yield and up to >99% ee) within a short reaction time (0.5 h). The practical utility of the method has been demonstrated in the gram-scale synthesis of chiral sulfoxide. Mechanistic studies, performed with ¹⁸O-labeled water (H₂¹⁸O), hydrogen peroxide (H₂¹⁸O₂), and cumyl hydroperoxide, reveal that a high-valent manganese–oxo species is generated as the oxygen atom delivering agent via carboxylic acid assisted heterolysis of O–O bonds. Density functional theory (DFT) calculations were also carried out to give further insight into the mechanism of manganese-catalyzed sulfoxidation. On the basis of the theoretical study, the coupled high-valent manganese­(IV)–oxo cation radical species, which bears obvious similarities with that of reactive intermediates in the catalytic oxygenation reactions based on the cytochrome P450 and metalloporphyrin models, has been proposed as the reactive oxidant in the non-heme manganese catalyst system

Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere

We report a new Fe­(NO₃)₃·9H₂O/9-azabicyclo­[3.3.1]­nonan-<i>N</i>-oxyl catalyst system that enables efficient aerobic oxidation of a broad range of primary and secondary alcohols to the corresponding aldehydes and ketones at room temperature with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliphatic alcohol oxidation. This procedure can also be scaled up. Kinetic analysis demonstrates that C–H bond cleavage is the rate-determining step and that cationic species are involved in the reaction