Search

Structurally precise metal nanoclusters with a facile synthetic process and high catalytic performance have been long pursued. These atomically precise nanocatalysts are regarded as model systems to study structure-performance relationships, surface coordination chemistry, and the reaction mechanism of heterogeneous metal catalysts. Nevertheless, the research on silver-based nanoclusters for driving chemical transformations is sluggish in comparison to gold counterparts. Herein, we report the one-step synthesis of Pt/Ag alloy nanoclusters of [PtAg9(C18H12Br3P)7Cl3](C18H12Br3P), which are highly active in catalysing cycloaddition reactions of CO2 and epoxides. The cluster was obtained in a rather simple way with the reduction of silver and platinum salts in the presence of ligands in one pot. The molecular structure of the titled cluster describes the protection of the Pt-centred Ag9 crown by the shell of phosphine ligands and halides. Its electronic structure, as revealed by density function theoretical calculations, adopts a superatomic geometry with 1S21P6 configuration. Interestingly, the cluster displays high activity in the formation of cyclic carbonates from CO2 under mind conditions. [ABSTRACT FROM AUTHOR]

Herein, we report a practical and mild synthetic protocol for a three-component reaction among alkenes, trifluoromethyl aromatics, and arylthiols. In this reaction, the selective C–F activation of trifluoromethyl aromatics occurs. The arenethiolate in the system plays dual roles: an electron donor and a radical trapping reagent. This process only releases a fluoride anion as a by-product within 2 hours. Moreover, the obtained difluoromethyl thioether could be further oxidized with meta-chloroperoxybenzoic acid (m-CPBA) to obtain unique yet challenging and almost unprecedented sulfonyl-based gem-difluoromethyl products with more than 36 substrates and up to 95% yield. Our protocol could easily scale up to yield 3.4 grams of product, which is the core structure required for further functionalization. These transformations can be applied to late-stage molecular development, which could be of great interest and potential in bio-relevant and pharmaceutical fields. Essentially, both experimental studies and DFT calculations were conducted and the results suggested a pathway of photo-induced EDA (electron donor–acceptor) complex, followed by a radical–radical cross-coupling process. [ABSTRACT FROM AUTHOR]

Bioactivity-guided isolation was conducted using centrifugal partition chromatography (CPC) from an extract of Sinomenium acutum rhizome, which has shown promising preventive effects in a dexamethasone-induced C2C12 myotube atrophy model. CPC was operated with a solvent system of n-butanol–acetonitrile–water (10:2:8, v/v/v, containing 0.5% triethylamine) in dual mode (ascending to descending), which provided a high recovery rate (>99%) with a high resolution. Then, the preventive effects of the obtained CPC fractions were examined against dexamethasone-induced atrophy in C2C12 myotubes according to the weight ratios of the obtained fractions. The active fractions were further purified by semi-preparative HPLC that led to obtaining five alkaloids, one lignan glycoside, and one phenylpropanoid glycoside. Among these, at a concentration of 1 nM, sinomenine, magnoflorine, and acutumine could ameliorate dexamethasone-induced myotube atrophy in C2C12 myotubes by 9.3%, 13.8%, and 11.3%, respectively. [ABSTRACT FROM AUTHOR]

A facile synthesis of atomically precise metal nanoclusters, especially those decorated with functional groups, is the prerequisite for finding applications in special fields and studying structure-and-property relationships. The exploration of simple and efficient synthetic prototypes for introducing functional ligands (such as ferrocene) into cluster moieties is thus of high interest. In this work, a type of reducing agent of dppfCuBH4 (dppf is 1,1′-bis(diphenyphosphino)ferrocene) is introduced for the first time to prepare ferrocene-functionalized metal nanoclusters. Two new clusters of [Ag25Cu4(dppf)6(3-F-PhC≡C)12Cl6]3+ (1) and [Ag4(dppf)5Cl2]2+ (2) have been obtained from the simple synthetic method. The two compounds have been fully characterized by advanced techniques of electrospray ionization mass spectroscopy (ESI-MS), nuclear magnetic resonance (NMR), and ultraviolet-visible spectroscopy (UV-Vis). The total structure of the clusters, as determined by X-ray single-crystal diffraction, describes the Ag13@Ag12Cu4(dppf)6(3-F-PhC≡C)12Cl6 core–shell structure of 1 and [Ag2Cl(dppf)2]+-dppf-[Ag2Cl(dppf)2]+ polymeric structure of 2. This work opens the door to employing dppfCuBH4 as a functional reducing agent to discover many underlying metal nanoclusters and even other nanomaterials which feature ferrocene-groups. [ABSTRACT FROM AUTHOR]

Background: There are only a few epidemiological reports available for reference. The clinicopathological features are not clear, so there is no consensus on treating rectal multiple neuroendocrine neoplasms. This study aims to summarize the clinicopathological characteristics and preliminarily discuss the clinical diagnosis and treatment of rectal multiple neuroendocrine neoplasms. Methods: This study retrospectively analyzed rectal neuroendocrine neoplasm patients diagnosed and treated at the Fourth Hospital of Hebei Medical University from February 2007 to May 2021. The clinicopathological characteristics of rectal multiple neuroendocrine neoplasms were summarized and analyzed in combination with 14 studies on rectal multiple neuroendocrine neoplasms. Results: The incidence of RM-NENs accounted for 3.8% of all R-NENs in this study. The number of tumors varied to some extent, the size of tumors was basically no more than 10 mm, and there were more G1 grade tumors. In the analysis of 46 cases with known lymph node metastasis, the difference in lymph node metastasis rate between the number of tumors < 8 and ≥ 8 was statistically significant (p = 0.002). Conclusions: The incidence of rectal multiple neuroendocrine neoplasms accounted for 3.8% of all rectal neuroendocrine neoplasms. For rectal multiple neuroendocrine neoplasms, the lymph node metastasis rate was higher when the number of tumors was ≥ 8. The influence of the number of tumors on lymph node metastasis should be considered in the selection of treatment. [ABSTRACT FROM AUTHOR]

C34H37NO6, triclinic, P1̄ (no. 2), a = 6.398(6) Å, b = 10.779(10) Å, c = 12.030(11) Å, α = 71.103(10)°, β = 89.519(11)°, γ = 74.154(11)°, V = 752.2(12) Å3, Z = 1, Rgt(F) = 0.0599, wRref(F2) = 0.1614, T = 296 K. [ABSTRACT FROM AUTHOR]

C34H37NO6, triclinic, P1̄ (no. 2), a = 6.398(6) Å, b = 10.779(10) Å, c = 12.030(11) Å, α = 71.103(10)°, β = 89.519(11)°, γ = 74.154(11)°, V = 752.2(12) Å3, Z = 1, Rgt(F) = 0.0599, wRref(F2) = 0.1614, T = 296 K. [ABSTRACT FROM AUTHOR]