Latest ArticlesA calix[4]arene ligand assisted direct β-C−H arylation of tertiary aliphatic aldehydes has been developed via a Pd-catalyzed C(sp3)−H functionalization process. This strategy exhibited good functional group compatibility and C−H bond site-selectivity. Mechanism studies have shown that both synergistic effect and cationic-π supramolecular interaction between calixarene cavity and transition-metal catalytic center may play an important role in this catalytic cycle. This complementary method would be used in organic and medical chemistry due to the importance of tertiary aliphatic aldehydes.
Metal-organic frameworks (MOFs) materials with highly ordered and porous crystalline structure, have excellent performance in advanced oxidation progresses (AOPs) for organic contaminants degradation in water treatment. This review intends to summarize the timely references and insights for the recent advances in MOFs that are used in AOPs. Starting with the preparation methodologies, including conventional hydrothermal method, electrochemical method, sol-gel method, and emerging microwave and ultrasound assisted synthesis methods. Application and mechanism for MOFs using in various AOPs of Fenton-like, photocatalysis, catalytic ozonation, persulfate catalysis and other emerging oxidation methods are emphatically discussed. We hope this review can comprehensively summarize the research and application progress of MOFs in AOPs, deepen the understanding of the catalytic mechanisms.
Two sulfonated diterpenoid alkaloids possessing different but related novel carbon skeletons, named aconidenusulfonine A (1) and 12, 16-secoaconidenusulfonine A (2), respectively, were isolated as minor components from an aqueous extract of the lateral roots of Aconitum carmichaelii ("Fu Zi"). The structures of 1 and 2, representing the first two C21-diterpenoid alkaloids from nature, were determined by analysis of various spectroscopic data and chemical transformation, of which 1 was further proved by single-crystal X-ray diffraction. Especially, 1 exhibited dose-depended analgesic activity consistent with the clinical function of Fu Zi.
Understanding and establishing the structure-activity relation of nanoparticles is a prerequisite for rational design of high-performance electrocatalysts. Cu2O nanoparticles enclosed with different crystal facets, namely, o-Cu2O NPs with {111} facets, c-Cu2O NPs with {100} facets are prepared and their electrocatalytic properties for oxygen evolution reaction (OER) in alkaline condition are evaluated at single nanoparticle level with a combination of scanning electrochemical cell microscopy and scanning electron microscopy. It is found that the o-Cu2O NPs have significantly superior OER electrocatalytic activity compared to c-Cu2O, which is almost inert. The estimated turnover frequency (TOF) at 1.97 V vs. RHE on {111} facet increases from 4 s−1 to 115 s−1 with the octahedron edge length decreasing from 1.3 µm to 100 nm. Deposition of carbon on c-Cu2O surface barely promotes the activity, suggesting the inherent poor electric conductivity within the nanocrystal is most likely the reason for low activity. This work provides direct probing to single transition metal oxide crystals with dramatically different activity.
Recently, exploiting a novel supramolecular fabrication pathway have drawn great attention. To this endeavor, we firstly designed and reported an original light-activated platform based on the internal-driven forces of macrocyclic host by hiring the pillar[5]arene as the host molecule (H) and phenazine derivatives acting as an energetic guest molecule (G). Surprisingly, after adding the H solution into G system, the intensive fluorescence emission of the G molecule rapidly decreased under the irradiation of the UV-light (254 nm) until absolutely quenching. Delightfully, different from the traditional supramolecular host-guest interaction, the fluorescent emission of G molecule could be recovered after irradiating under the nature light. In view of this interesting observations, the interaction mechanism was carefully investigated by a series of characterizations. Those results suggested that the G molecule was easily threaded into the macrocyclic cavity (H) under the internal-driven forces induced by the UV-light irradiation, forming a 1:1 host-guest complex. Moreover, taking advantage of this especial feature, the light-activated platform of host–guest complex was further applied for ink-free light-driven printing materials, exhibiting great potential in the real application.
The construction of secondary alkylsilanes is a challenging subject in the synthetic community. The cross-coupling provides a practical solution to address this problem, but it typically relies on organometallic species. Herein, we report an Mn-mediated reductive C(sp3)–Si coupling to synthesize these compounds from alkyl and silyl electrophiles. This approach avoids the requirement for activation of Si–Cl by transition metals and thus allows for the coupling of various common chlorosilanes. The reaction proceeds under mild conditions and shows good functional group compatibility. The method offers access to α-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.
Highly enantioselective Rh-catalyzed partial hydrogenation of unprotected simple 2-alkyl-5-aryl-disubstituted pyrroles has been successfully developed, generating a series of chiral 1-pyrroline derivatives generally with excellent results (95%–99% yields, 91%–96% ee). Moreover, 2,5-aryl-1H-pyrroles were hydrogenated well in high yields and good enantioselectivities. This efficient protocol features easily accessible substrates, wide substrate scope, well functional group compatibility, commercially available rhodium precursor and chiral ligand. It provides a versatile route to access chiral 1-pyrroline derivatives that are of great importance in organic synthesis and pharmaceutical chemistry.
Protecting clusters from coalescing by ligands has been universally adopted in the chemical synthesis of atomically precise clusters. Apart from the stabilization role, the effect of ligands on the electronic properties of cluster cores in constructing superatoms, however, has not been well understood. In this letter, a comprehensive theoretical study about the effect of an organic ligand, methylated N-heterocyclic carbene (C5N2H8), on the geometrical and electronic properties of the aluminum-based clusters XAl12 (X = Al, C and P) featuring different valence electron shells was conducted by utilizing the density functional theory (DFT) calculations. It was observed that the ligand can dramatically alter the electronic properties of these aluminum-based clusters while maintaining their structural stability. More intriguingly, different from classical superatom design strategies, the proposed ligation strategy was evidenced to possess the capability of remarkably reducing the ionization potentials (IP) of these clusters forming the ligated superalkalis, which is regardless of their shell occupancy. The charge transfer complex formed during the ligation process, which regulates the electronic spectrum through the electrostatic Coulomb potential, was suggested to be responsible for such an IP drop. The ligation strategy highlighted here may provide promising opportunities in realizing the superatom synthesis in the liquid phase.
Once inevitably released into the aquatic environment, polystyrene nanoplastics (PS-NPs) will present complicated environmental behaviors, of which the aggregation is a key process determining their environmental fate and impact. In this study, the aggregation kinetics of different sizes (30 nm and 100 nm) of PS-NPs with metal cations (Na+, K+, Ca2+, Mg2+ and Pb2+) at different solution pH (3, 6 and 8) were investigated. The results showed that the aggregation of PS-NPs increased with cation concentration. Taking Pb2+ as an example, the adsorption behavior of cations onto PS-NPs was determined by transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) spectroscopy, which demonstrated Pb2+ could be adhered onto the surface of PS-NPs with the effect of charge neutralization. The critical coagulation concentrations (CCC) of smaller PS-NPs were higher than that of larger PS-NPs for monovalent cations, whereas a different pattern is observed for divalent cations. It was suggested that there were other factors that DLVO theory does not consider affect the stability of NPs with different particle sizes. In addition, it should be noted that PS-NPs had the capacity of adsorbing large amounts of heavy metal cations and carried them transport to a long distance, and the corresponding ecological risks need to further elucidate.
Difunctionalization of alkenes have developed into an important type of reactions for rapidly and efficiently assemble complex molecules. While extensive advancements have been achieved by the assistance of transition metal catalysis, the employment of cheap, abundant aryl chlorides as coupling partner is still a challenging task in this field. Herein, we report our first achievement in 1,1-difunctionalization of alkenes with aryl chlorides as coupling partners. The success is predominantly ascribed to the judicious selection of 1,2-diamine ligand. This study provides an efficient protocol for the synthesis of secondary benzyl boronates from easily accessible feedstock chemicals. Furthermore, the distinguished features of this method include excellent 1,1-regio- and chemoselectivity, good functional group tolerance and easily-operational catalytic reaction conditions.