钨系催化合成1,2-聚丁二烯的研究——Ⅰ.主催化剂WCl_6-醇(酚)体系对聚合活性的影响

本工作研究了以Al(i-Bu)_3为助催化剂,WCl_6-醇(酚)体系对聚合活性的影响。结果表明,WCl_6-醇体系的聚合活性比 WCl_6-酚体系高,其中 WCl_6-C_4H_9OH 体系最高;在 WCl_6-酚体系中随酚的酸性减弱,聚合活性增强。WCl_6-醇(酚)体系的ESR谱指出,体系中有氧化-还原反应,活性价态低于W(V)。两类体系均能得到 1,2-结构含量>80％的聚合产物。     

Hydroformylation of functional alkenes with heterodonor phosphine rhodium catalysts: substrate or ligand directed regioselectivity?

The catalytic activity and selectivity of heterodonor phosphine rhodium catalysts prepared in situ were tested in the hydroformylation of functional alkenes (ethyl acrylate, methyl methacrylate, styrene, 4-vinyl-1-cyclohexene, dicyclopentadiene and cis-1,2,3,6-tetrahydrophthalic anhydride). Systematic variation of the heterodonor atom in the ortho position of the ligand showed that the heterodonor atom has a significant influence on the activities and selectivities of the reaction. However, the activity seems to depend mainly on the modifying ligand, and the regioselectivity mainly on the substrate (i.e., the structure and functionality of the alkene). Nevertheless, regioselective control is only obtained through synergy between the substrate and the catalyst. Clear regiocontrol was observed in the hydroformylation of ,-unsaturated esters and styrene with an in situ formed o-(thiomethylphenyl)diphenylphosphine rhodium catalyst.     

Arsenical grafted membranes for immobilization of thioredoxin-like proteins

In this work, we describe the cografting of glycidyl methacrylate and dimethyl acrylamide onto a macroporous polysulfone polymer. Aminophenyl arsenical compounds were covalently attached to the copolymer through epoxy ring add-on reactions followed by a 2-mercaptoethanol activation. Thioredoxin and thioredoxin-fusion proteins were immobilized onto this surface and detected by specific antibody recognition. Preservation of native protein folding was confirmed by the detection of the enzymatic activity of an unstable fusion protein. Immobilized fusion protein onto the modified material maintains the enzymatic activity for a longer time, up to two weeks, against the free protein under the same storage conditions that remains active for 2 days.     

Synthesis, crystal structure and photophysical properties of a series of new neutral iridium(III) complexes with 2-phenylpyridine

A series of new neutral iridium(III) complexes containing strong-field ancillary ligands, [Ir(ppy)₂(PPh₃)L] (ppy = 2-phenylpyridine, PPh₃ = triphenylphosphine, L = NCS⁻, 1; , 2; NCO⁻, 3), have been synthesized and fully characterized by ¹H NMR, IR, ESI mass spectral and elemental analysis. The crystal structure of 1 has been determined by X-ray analysis. The photoluminescence (PL) spectra of 1–3 show emission maxima at 477, 489 and 485 nm, respectively, corresponding to blue light-emitting of 1 and blue-green light-emitting of 2 and 3. PL quantum yields (PLQYs) of 1–3 are 0.39, 0.13 and 0.43, respectively.     

Vinyl polymerization of norbornene with bis(imino)pyridyl nickel(II) complexes

A series of different steric hindrance nickel(II) complexes 1 – 6 bearing 2,6‐bis(imino)pyridine ligands have been synthesized and characterized. The molecular structures of the complexes 3 – 5 were determined by X‐ray diffraction analysis. The coordination geometry around the nickel center of the complexes is either square pyramid for complexes 3 and 4 or trigonal bipyramid for complex 5 . All of the nickel complexes exhibit high catalytic activity for norbornene polymerization in the presence of MAO, although low activity for ethylene oligomerization and polymerization. The effects of the Al/Ni ratio, halogen, monomer concentration, temperature, and reaction time on activity of catalyst for norbornene polymerization and polymer microstructure were investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Cytotoxic Rhodium(III) and Iridium(III) Polypyridyl Complexes: Structure–Activity Relationships,Antileukemic Activity,and Apoptosis Induction

Whereas the cytostatic agents mer‐[RhX₃(DMSO)(pp)] (X=Cl, Br; pp=phen, dpq) are considerably more potent than their facial isomers, this order is reversed for the analogous kinetically more inert Ir^III polypyridyl complexes. The complexes induce specific apoptotic cell death in leukemia and lymphoma cells via the intrinsic mitochondrial pathway and cause negligible necrotic damage.

     

4,4‐Dimethyl‐ and Diastereomeric 4‐Hydroxy‐4‐methyl‐ (2S)‐Glutamate Analogues Display Distinct Pharmacological Profiles at Ionotropic Glutamate Receptors and Excitatory Amino Acid Transporters

Subtype‐selective ligands are of great interest to the scientific community, as they provide a tool for investigating the function of one receptor or transporter subtype when functioning in its native environment. Several 4‐substituted (S)‐glutamate (Glu) analogues were synthesized, and altogether this approach has provided important insight into the structure–activity relationships (SAR) for ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs), as well as the excitatory amino acid transporters (EAATs). In this work, three 4,4‐disubstituted Glu analogues 1 – 3 , which are hybrid structures of important 4‐substituted Glu analogues 4 – 8 , were investigated at iGluRs and EAATs. Collectively, their pharmacological profiles add new and valuable information to the SAR for the iGluRs and EAAT1–3.     

DiPAMP’s Big Brother “i‐Pr‐SMS‐Phos” Exhibits Exceptional Features Enhancing Rhodium(I)‐Catalyzed Hydrogenation of Olefins

Switching Knowles DiPAMP’s {DiPAMP=1,2‐bis[(o‐anisyl)(phenyl)phosphino]‐ ethane} MeO groups with i‐PrO ones led to the i‐Pr‐SMS‐Phos {i‐Pr‐SMS‐Phos=1,2‐bis[(o‐isoprop‐ oxyphenyl)(phenyl)phosphino]ethane} ligand which displayed a boosted catalyst activity coupled with an enhanced enantioselectivity in the rhodium(I)‐catalyzed hydrogenation of a wide‐range of representative olefinic substrates (dehydro‐α‐amido acids, itaconates, acrylates, enamides, enol acetates, α,α‐diarylethylenes, etc). The rhodium(I)‐(i‐Pr‐SMS‐Phos) catalytic profile was investigated revealing its structural attributes and robustness, and in contrast to the usual trend, ³¹P NMR analysis revealed that its methyl (Z)‐α‐acetamidocinnamate (MAC) adduct consisted of a reversed diastereomeric ratio of 1.4:1 in favour of the most reactive diastereomer.