Engineering the Activity and Stability of the Zn-MOF Catalyst via the Interaction of Doped Zr with Zn.

Metallic atoms within metal-organic framework (MOF) materials exhibit a distinctive and adaptable coordination structure. The three-dimensional (3D) pore configuration of MOFs enables the complete exposure of metal active sites, rendering them prevalent in various catalytic reactions. In this study, zinc (Zn) atoms within Zn-based MOF materials, characterized by an abundance of valence electrons, are utilized for the transesterification of dimethyl carbonate (DMC). Additionally, the introduction of zirconium (Zr) effectively addresses the susceptibility of the MOFs' crystal structure to dissolution in organic solvents. The formulated catalyst, Zn-10%Zr-MOF(300), demonstrates remarkable catalytic performance with 91.5% DMC selectivity, 61.9% propylene carbonate (PC) conversion, and 56.6% DMC yield. Impressively, the catalyst maintains its high performance over five cycles. Results indicate that Zr interacts with Zn, forming new coordination bonds and enhancing the catalyst crystal structure stability. Moreover, electron transfer intensifies the alkalinity of the active Zn atoms, enhancing the overall catalyst performance. This research informs the development of transesterification heterogeneous catalysts and broadens the application scope of MOF catalysts.

Dish spliced concentrator with both uniform and focused performance through a variable focal length.

We present a dish spliced concentrator (DSC) featuring hexagonal spherical sub-mirrors of uniform size. The DSC offers advantages over traditional parabolic dish concentrators, including a compact layout, cost-effectiveness, higher concentration ratio, and improved light uniformity. Its versatility allows for both uniform and focused light concentration by adjusting parameters like the focal length of the DSC, making it suitable for concentrating photovoltaic (CPV) and concentrating solar thermal (CST) applications. We design the DSC using three-dimensional (3D) vector rotation theory, implementing ray tracing and transmission characteristic analysis based on three-dimensional vector reflection theory. We establish a simulation model to evaluate the impact of geometric parameters on the DSC's optical performance.

Design of a compact off-axis two-mirror freeform optical antenna for shaping and transmitting an elliptical beam emitted by laser diode.

Elliptical Gaussian beams generated by laser diodes (LDs) often exhibit asymmetrical divergence angle distribution, which limits their practical applications. In this study, we propose what we believe is a novel approach to shape and collimate the elliptical output beam from a LD. The design process involves the construction of two freeform reflective surfaces on a reference circle using a three-dimensional point-by-point iterative method, based on the law of conservation of energy, the vector reflection theory, and Fermat's principle. The output beam's maximum divergence angle is effectively compressed to 3.1579 mrad. The design is compact with a folded optical path and antenna size of 368.8c m 3. This paper presents a comprehensive design and optimization process, along with an in-depth analysis of the system's performance, thereby offering novel insights for emerging optical design practitioners.

A Systematic Review on the Research Progress on Polysaccharides from Fungal Traditional Chinese Medicine.

Traditional Chinese medicine (TCM) is a class of natural drugs with multiple components and significant therapeutic effects through multiple targets. It also originates from a wide range of sources containing plants, animals and minerals, and among them, plant-based Chinese medicine also includes fungi. Fungal traditional Chinese medicine is a medicinal resource with a long history and widespread application in China. Accumulating evidence confirms that polysaccharide is the main pharmacodynamic material on which fungal TCM is based. The purpose of the current systematic review is to summarize the extraction, isolation, structural identification, biological functions, quality control and medicinal and edible applications of polysaccharides from fungal TCM in the past three years. This paper will supplement and deepen the understanding and application of polysaccharides from fungal TCM, and propose some valuable insights for further research and development of drugs and functional foods.

Vanadium complexes bearing 8-anilide-5,6,7-trihydroquinoline ligands for ethylene (co-)polymerization.

Several trivalent and pentavalent vanadium complexes bearing 8-anilide-5,6,7-trihydroquinoline ligands were synthesized. These vanadium complexes were identified by elemental analysis, FTIR spectroscopy and NMR. Single crystals of trivalent vanadium complexes V2, V3', and V4 and pentavalent vanadium complexes V5 and V7 were further obtained and identified by X-ray single crystal diffraction. In addition, the catalytic performance of these catalysts was adjusted by controlling the electronic and steric effects of substituents in the ligands. In the presence of diethylaluminium chloride, complexes V5-V7 displayed high activity (up to 82.8 × 106 g molV-1 h-1) and good thermal stability toward ethylene polymerization. In addition, the copolymerization ability of complexes V5-V7 was evaluated, and complexes V5-V7 displayed high activity (up to 105.6 × 106 g molV-1 h-1) and high copolymerization ability toward ethylene/norbornene copolymerization. By adjusting the polymerization conditions, copolymers with norbornene insertion ratios of 8.1%-30.9% can be obtained. Complex V7 was further studied for ethylene/1-hexene copolymerization, and the obtained copolymer displayed a moderate 1-hexene insertion ratio of 1.2%. Complex V7 displayed high activity and high copolymerization ability while having thermal stability. The results showed that 8-anilide-5,6,7-trihydroquinoline ligands with fused rigid-flexible rings were beneficial for vanadium catalysts.

Insight of "Yin-Jing" medical property ofLigusticum chuanxiong Hort. via pharmacokinetics and tissue distributions by ultra-performance liquid chromatography-triple quadrupole mass spectrometry.

ETHNOPHARMACOLOGICAL RELEVANCE: Ligusticum chuanxiong Hort. (Chuanxiong, LC), as an important traditional Chinese medicine (TCM), can not only be used as a monarch herb but also be used as a classic "Yin-Jing" () medicine in compound prescriptions, e.g., Buyang Huanwu Decoction (BHD). Although LC has the effect of guiding components into the brain in BHD, there is still a lack of scientific evidence on this "Yin-Jing" effects. Herein, we used pharmacokinetics and tissue distributions to investigate "Yin-Jing" effects of LC. To simplify the study, four major constituents in BHD, i.e., Calycosin (CA), astragaloside IV (AI), paeoniflorin (PA), and amygdalin (AM) were combined to form a simple compound (abbreviated as CAPA here) to replace the original BHD in this paper. The Yin-Jing medical property of LC was confirmed by the compatibility of CAPA with LC or its different fractions (Fr. A âˆ¼ Fr. F). AIM OF THE STUDY: To explore the "Yin-Jing" medical property of LC via pharmacokinetics and tissue distributions by ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QQQ-MS). MATERIALS AND METHODS: The contents of CA, AI, PA, and AM were simultaneously determined by the established and validated UPLC-QQQ-MS method in different rat tissues and plasma after administration of CAPA with the combination of LC or Fr. A âˆ¼ Fr. F. The pharmacokinetic parameters, e.g., Tmax, Cmax, AUC0-t and MRT0-t, were calculated to evaluate the efficiency of "Yin-Jing". RESULTS: The Cmax and AUC0-t of CA, AI, PA, and AM were remarkably increased in rat brain tissues compared with those of the control group after compatibility of LC. This demonstrated that LC has the Yin-Jing effects on brain tissues. Additionally, Fr. B or Fr. C might be the material basis by specifically studying the distributions of CA, AI, PA, and AM in brain tissue based on mutual compatibility. The effects of Fr. B and Fr. C on distributions of these constituents in other tissues or plasma was also studied to verify the effects of Yin-Jing of LC. The results showed that the same upward trend is found in heart, liver and plasma, but the intensity is insignificant as that in brain tissue. Furthermore, the Cmax and AUC0-t of some analytes in the rat spleen, lung, and kidney were significantly decreased compared with the control group (P < 0.05 or 0.01). CONCLUSIONS: LC has the function of Yin-Jing, especially guiding the components into the brain tissue. Moreover, Fr. B and Fr. C is suggested to be the pharmacodynamic material basis for the effect of Yin-Jing of LC. These finding explained that it was recommended to add LC into some prescriptions for treating cardiovascular and cerebrovascular diseases caused by Qi deficiency and blood stasis. This has laid a certain foundation for the research on the Yin-Jing efficacy of LC to better clarify the theory of TCM and guide the clinical application of Yin-Jing drugs.

Renewable Vanillin-Based Thermoplastic Polybutadiene Rubber: High Strength, Recyclability, Self-Welding, Shape Memory, and Antibacterial Properties.

The vast majority of traditional vulcanized rubber products are insoluble and infusible, which is difficult to reprocess and biodegrade, resulting in black pollution. In addition, although most rubber materials based on covalent adaptive networks (CANs) can achieve structural reconstruction, the lack of traditional vulcanization system leads to a decline in strength. In this study, biobased vanillin derivatives (PV) were synthesized to cross-link the commercially available 1,2-polybutadiene rubber precursor to construct imine-based CANs, thereby fabricating a resource-renewable, recyclable, and degradable high-performance rubber material. Due to the rigid tripod structure of the PV, the tensile strength of the material can achieve as high as 16.24 MPa, ranking among the best in the field of recyclable polybutadiene-based materials. Benefiting from the dynamic imine unit, the "dynamic covalent bridge" can be re-established to repair the damaged network and endow the material with excellent weldability. And, shape memory faculty of the material was proved and depicted. Moreover, this material displayed excellent antibacterial property originates from the introduced Schiff-base structure. By mixing with graphene, the application of action sensors can also be achieved.

[Study on drug properties of Arisaematis Rhizoma and Arisaema Cum Bile based on substance and energy metabolism in normal and cold/heat syndrome model rats].

This paper clarified the scientific connotation of the changes in cold and heat properties of Arisaematis Rhizoma and Arisaema Cum Bile through investigating the changes of substance and energy metabolism after drug intervention in the rats with normal and cold/heat syndrome, so as to improve the method of evaluating the drug properties of Chinese medicine. After one week of adaptive feeding, healthy male SD rats were randomly divided into three parts: normal rats, heat syndrome rat models, and cold syndrome rat models. Through ice water bath and oral euthyrox(120 µg·kg~(-1)), the models of cold syndrome and heat syndrome were induced, respectively. The models were made at 9:00 am. and administrated by gavage at 3:00 pm. every day. All administration groups were administrated with Arisaematis Rhizoma and Arisaema Cum Bile decoction, respectively, and the blank group was given the same dose of normal saline. After continuous administration for 15 d, the rats were anesthetized by chloral hydrate, blood was taken from abdominal aorta, and the hearts and livers were removed and stored at-80 ℃. The changes in the body weight and anal temperature of rats during administration were detected, and the liver coefficient of rats was detected after removing the liver. Enzyme-linked immunosorbent assay(ELISA) was adopted to detect the expression level of the indexes related to substance and energy metabolism in liver and heart of rat, and Western blot was used to detect the expression of key proteins in AMPK/mTOR signaling pathway for further verification. The results showed that Arisaematis Rhizoma enhanced the expression level of enzymes related to substance and energy metabolism in the normal and cold and heat syndrome rat models, and increased anal temperature, which exhibited warm(hot) drug property. Arisaema Cum Bile inhibited the level of substance and energy metabolism in rats, and reduced anal temperature, which showed cold(cool) drug property. Chinese Pharmacopoeia has recorded "Arisaematis Rhizoma has warm property and Arisaema Cum Bile has cool property", which is consistent with the phenomenon in this study. Therefore, it is feasible to evaluate the drug properties of Chinese medicine based on the substance and energy metabolism of normal and cold/heat syndrome model rats, which completes the method of evaluating drug properties of Chinese medicine.

Cattle Bile Arisaema Aqueous Extracts Protect Against Febrile Seizures in Rats Through Regulating Neurotransmitters and Suppressing Neuroinflammation.

Cattle bile Arisaema (CBA) is a traditional medicine used for the treatment of febrile seizures (FS) for thousands of years in China. However, its application is greatly limited due to cost reasons, and pig bile Arisaema (PBA) is the main commercial product instead. Additionally, the underlying mechanism of CBA for the treatment of FS still remains unknown. In this study, we investigated the anti-convulsant effect and potential mechanism of the CBA aqueous extract for the first time through a hot-water bath-induced FS rat model. Our results showed that pre-treatment with CBA dramatically lowered the incidence rate and generation times and prolonged the latency of FS. In addition, CBA effectively ameliorated neuronal damage and regulated neurotransmitter disorder induced by FS in the rat hippocampus. The enzyme-linked immunosorbent assay, western blotting, immunohistochemical, and qRT-PCR results exhibited that CBA suppressed the expression of GFAP, TLR4, NF-κB, HMGB1, NLRP3, TNF-α, IL-1ß, and IL-6 and consequently inhibited the neuroinflammation induced by FS. Interestingly, although the CBA and PBA aqueous extracts possessed the same trend on the changes caused by FS, the improvement of FS by CBA is markedly better than that by PBA. These findings indicate that CBA exerts a protective effect on febrile seizures through regulating neurotransmitter disorder and suppressing neuroinflammation.

Self-Strengthening, Self-Welding, Shape Memory, and Recyclable Polybutadiene-Based Material Driven by Dual-Dynamic Units.

A covalent adaptable network can endow rubber materials with recyclability and reprocessability and is expected to alleviate black pollution caused by end-of-life rubber. However, the loss of traditional vulcanization systems severely sacrifices their strength, and the tensile strength in the current study rarely exceeds 10 MPa unless fillers are added. In this work, we proposed a self-strengthening process based on dual-dynamic units (imine and disulfide), briefly, under heating, phenylsulfur radicals generated from aromatic disulfide bonds can react with double bonds (mostly vinyl) and/or couple with allyl sites, thus reforming a stronger cross-linked network. The neighboring imine unit is not affected and provides excellent thermal reprocessability and chemical recyclability. The result shows that the tensile strength can reach 19.27 MPa via self-strengthening without adding fillers or any other additives, and this ultra-high-strength is much higher than those of all known recyclable polybutadiene-based rubber materials. In addition, the material also has malleability, shape memory, and self-welding properties. By doping carbon nanotubes, a recyclable conductive composite can also be achieved. In general, we envision that this enhanced strategy has great potential to be generalized for all elastomers containing double bonds (such as styrene-butadiene rubber, nitrile rubber, isoprene rubber, and their derivatives). The reprocessability and self-welding are practical for on-site assembly or repair of composite parts and extend the service life of materials.

A comprehensive review of research progress on the genus Arisaema: Botany, uses, phytochemistry, pharmacology, toxicity and pharmacokinetics.

ETHNOPHARMACOLOGICAL RELEVANCE: The genus Arisaema belongs to the family Araceae, which includes Chinese herbal medicines with wide-ranging pharmacological functions, including those useful for the treatment of stubborn phlegm, cough, epilepsy, tetanus, snakebite, rheumatoid arthritis, and other ailments. AIM OF THE STUDY: The current study aimed to comprehensively review the botany, uses, phytochemistry, pharmacology, toxicity, quality control and pharmacokinetics of plants in the genus Arisaema and to provide novel insights to develop future research in this field. MATERIALS AND METHODS: Relevant information on the genus Arisaema was obtained from published scientific materials (including materials from PubMed, Elsevier, Web of Science, Google Scholar, Baidu Scholar, CNKI, and Wiley) and other literature sources (e.g., the Chinese Pharmacopoeia, 2020 edition; Chinese herbal books and PhD and MSc thesis). RESULTS: The application information complied with this review and included processing techniques, traditional uses, clinical applications and classic prescriptions. Approximately 260 compounds, including flavonoids, alkaloids, saccharides, steroids, fatty acids, amino acids and volatile oils, have been separated and identified from the genus Arisaema. The isolated compounds exhibit wide-ranging pharmacological activities such as antitumor activity, analgesic and sedative activity, antioxidant activity and anti-inflammatory activity. The toxicity and irritant impacts, quality control, and pharmacokinetics are also discussed in this review. CONCLUSIONS: Plants in the genus Arisaema are valuable resources with therapeutic potential for a broad spectrum of ailments. Based on the limited literature, this review comprehensively and systematically summarizes current knowledge regarding the genus Arisaema for the first time. However, there have been insufficient studies on the active ingredients and germplasm and insufficient in-depth mechanistic studies. Therefore, isolation and identification of additional effective components and through research on the germplasm, pharmacodynamic mechanisms, and toxicology should be conducted to assess effectiveness and safety and to ensure the quality of the related drugs.

Thermally stable vanadium complexes supported by the iminophenyl oxazolinylphenylamine ligands: synthesis, characterization and application for ethylene (co-)polymerization.

In this work, a series of oxovanadium complexes bearing the ligands (S,E)-(+)-2, 6-dialkyl-N-(2-((2-(4-isopropyl-4,5-dihydrooxazole-2-yl)phenyl)amino)benzylidene)aniline (dialkyl = dimethyl (V1), diethyl (V2), and isopropyl (V3)) have been synthesized and characterized by FTIR spectroscopy and elemental analysis. Moreover, the molecular structures of complexes V2 and V3 were defined by X-ray diffraction. On activation with ethylaluminium sesquichloride (Al2Et3Cl3), these complexes exhibited high activity towards ethylene polymerization (up to 1.39 × 107 g molv-1 h-1) and showed excellent thermal stability (up to 60 °C). The obtained polyethylene had a moderate molecular weight (21.9 × 104 to 66.4 × 104 g mol-1) and exhibited narrow distribution (1.91 to 2.86) and unimodal features. The effect of the substituents on the ligands was also investigated in detail. The compound bearing the diisopropyl group showed the highest activity toward ethylene polymerization as the bimolecular deactivation of the catalyst can be effectively inhibited by the steric hindrance of the ortho-substituent on aniline. The complex V2 with moderate steric hindrance was also evaluated as a catalyst for the copolymerization of ethylene with norbornene and showed moderate to high activity.

Catalyst-Free Vitrimer Cross-Linked by Biomass-Derived Compounds with Mechanical Robustness, Reprocessability, and Multishape Memory Effects.

Vitrimerization of thermoset polymers plays an important role in addressing resource recovery and reuse. Vitrimer elastomers with good mechanical properties often require well-designed crosslinking agents or fillers, but this increases processing complexity or reduces vitrimer dynamic properties. In this report, a simple green strategy to build a strong vitrimer elastomer is designed. Commercially available epoxidized natural rubber (ENR) is cross-linked with biomass-derived D-Fructose 1,6-bisphosphoric acid to get a vitrimer elastomer cross-linked by ß-hydroxy phosphate ester bonds and has abundant hydrogen bonds. Hydrogen bonds can preferentially break and dissipate energy under external forces, which makes the sample robust. The topological network can be reformed at high temperatures through the dynamic exchange of ß-hydroxy phosphate ester bonds, which gives the material malleability and recyclability. In addition, through the strategy of combining reprocessing and welding, multiple shape memory effects can be achieved in one postprocessing step. Considering that a variety of commercially available epoxy polymers are easily available, it is believed that this strategy can be a simple and versatile way to enable commercial epoxy polymers to achieve green crosslinking through biomass crosslink agents, which results in robust and recyclable vitrimers based on ß-hydroxy phosphate bonds.

An In-Situ Self-regeneration Catalyst for the Production of Renewable Penta-1,3-diene.

Catalyst deactivation is a problem of great concern for many heterogeneous reactions. Here, an urchin-like LaPO4 catalyst was easily developed for pentane-2,3-diol dehydration; it has an impressive ability to restore the activity in situ by itself during the reaction, accounting for its high stability. This facilitates the efficient production of renewable penta-1,3-diene from pentane-2,3-dione via a novel approach, where penta-2,3-diol was obtained as an intermediate in 95 % yield under mild conditions.

Assembling of Reprocessable Polybutadiene-Based Vitrimers with High Strength and Shape Memory via Catalyst-Free Imine-Coordinated Boroxine.

Vitrimers endow cross-linked polymers with malleability and reprocessability via exchange reactions. However, designing of reprocessable, shape-memory polymer materials with high strength via a catalyst-free method remains a challenge under mild conditions. Here, we propose a facile strategy to address this dilemma by introducing the exchangeable imine bond and N-coordinated boroxine into a polybutadiene (PB)-based network. Specifically, PB grafted with 2-aminoethanethiol is reacted with the formyl group of phenylboronic acid and dehydrated to form a dual-dynamic covalently cross-linked network at room temperature. The dynamic network draws on the advantage of imine (toughness) and N-coordinated boroxine (strength), making the PB-based materials exhibit favorable malleability, mechanical property, reprocessability, and thermal-induced shape-memory behavior. We can obtain customized high mechanical properties by tuning the cross-linking density, and the tensile strength reaches a high value (12.35 MPa) without fillers or any other additives. Meanwhile, the unique network framework makes the material recycle over several times without sacrificing its property. This work presents a facile and effective approach to achieve a multifunctional polymer with customized attributes. Besides, this strategy can recycle end-of-life rubber to alleviate environmental pollution and provide inspiration for fabricating targeted materials by uniting the dynamic covalent or noncovalent bonds.

Facile synthesis of hierarchically porous carbonaceous materials derived from olefin/aldehyde precursors using silica as templates.

Porous carbon is exceptionally useful, but it remains a great challenge to develop a facile route to prepare porous carbon materials with hierarchical structure and enhanced porosity. This work demonstrates a novel synthetic pathway for hierarchical carbonaceous materials (HCM) using isobutene and formaldehyde as carbon precursors via silica templates impregnated with phosphorus. Different from the traditional nanocasting method, the formation of the carbon structure is caused by heavy coke deposits on the solid catalyst in the course of the olefin/aldehyde vapor reaction. The coke-derived carbonaceous materials indicated by transmission electron microscopy (TEM) and nitrogen adsorption-desorption measurement are hierarchically mesoporous structures with a large surface area (971 m2 g-1) and pore volume (1.91 cm3 g-1). We have demonstrated for the first time that the olefin/aldehyde reaction may provide a convenient route to develop a porous carbon texture. The newly developed method may lead to porous carbon having scientific and technological importance in adsorption and catalysis applications.

Black liquor-derived carbonaceous solid acid catalyst for the hydrolysis of pretreated rice straw in ionic liquid.

Lignin-containing black liquor from pretreatment of rice straw by KOH aqueous solution was applied to prepare a carbonaceous solid acid catalyst, in which KOH played dual roles of extracting lignin from rice straw and developing porosity of the carbon material as an activation agent. The synthesized black liquor-derived carbon material was applied in catalytic hydrolysis of the residue solid from the pretreatment of rice straw, which was mainly composed of cellulose and hemicellulose, and showed excellent activity for the production of total reducing sugars (TRS) in ionic liquid, 1-butyl-3-methyl imidazolium chloride. The highest TRS yield of 63.4% was achieved at 140°C for 120min, which was much higher than that obtained from crude rice straw under the same reaction conditions (36.6% TRS yield). Overall, this study provides a renewable strategy for the utilization of all components of lignocellulosic biomass.

Iminopyridine-Based Cobalt(II) and Nickel(II) Complexes: Synthesis, Characterization, and Their Catalytic Behaviors for 1,3-Butadiene Polymerization.

A series of iminopyridine ligated Co(II) (1a⁻7a) and Ni(II) (1b⁻7b) complexes were synthesized. The structures of complexes 3a, 4a, 5a, 7a, 5b, and 6b were determined by X-ray crystallographic analyses. Complex 3a formed a chloro-bridged dimer, whereas 4a, 5a, and 7a, having a substituent (4a, 5a: CH3; 7a: Br) at the 6-position of pyridine, producing the solid structures with a single ligand coordinated to the central metal. The nickel atom in complex 5b features distorted trigonal-bipyramidal geometry with one THF molecule ligating to the metal center. All the complexes activated by ethylaluminum sesquichloride (EASC) were evaluated in 1,3-butadiene polymerization. The catalytic activity and selectivity were significantly influenced by the ligand structure and central metal. Comparing with the nickel complexes, the cobalt complexes exhibited higher catalytic activity and cis-1,4-selectivity. For both the cobalt and nickel complexes, the aldimine-based complexes showed higher catalyst activity than their ketimine counterparts.

Synthesis of bis(N-arylcarboximidoylchloride)pyridine cobalt(II) complexes and their catalytic behavior for 1,3-butadiene polymerization.

A new family of bis(N-arylcarboximidoylchloride)pyridine cobalt(II) complexes with the general formula [2,6-(ArN=CCl)2C5H3N]CoCl2 (Ar = 2,4,6-Me3C6H2, 4a; 2,6-(i)Pr2C6H3, 4b; 2,6-Me2C6H3, 4c; C6H5, 4d; 4-Cl-2,6-Me2C6H2, 4e) and a typical Brookhart-Gibson-type reference complex [2,6-(2,4,6-Me3C6H2N=CMe)2C5H3N]CoCl2 (5a) were synthesized and characterized. Determined by X-ray crystallographic analysis, complexes 4a, 4c-e, and 5a adopted a trigonal bipyramidal configuration, and 4b adopted a distorted square pyramidal geometry. In combination with ethylaluminum sesquichloride (EASC), all the complexes were highly active towards 1,3-butadiene polymerization, affording polybutadiene with predominant cis-1,4 content (up to 96%). 4a with chlorine atoms at the imine groups exhibited higher catalytic activity than did 5a, indicating that the incorporation of chlorine atoms into the ligand improves the activity. The activity of the complexes in 1,3-butadiene polymerization was in the order of 4a > 4c ∼ 4e ∼ 4b > 4d, which is consistent with the trend of spatial opening degree around the metal center in the complexes as revealed by crystallographic data. Screening polymerization conditions proved that EASC was the most efficient among the cocatalysts examined.

Lewis-acid assisted cross metathesis of acrylonitrile with functionalized olefins catalyzed by phosphine-free ruthenium carbene complex.

The exchange of the PPh3 ligand in the complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](PPh3)(Cl)2Ru=CHPh (7) for a pyridine ligand at ambient temperature leads to the formation of the stable phosphine-free carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](C5H5N)2(Cl)2 Ru=CHPh (8). The resulted ruthenium complex exhibits highly catalytic activity for the cross metathesis of acrylonitrile with various functionalized olefins under mild conditions, and its activity can be further improved by the addition of a Lewis acid such as Ti(OiPr)4. In the mixture products, the Z-isomer predominates.