β-二酮-茂基二氯化钛/MAO催化体系用于苯乙烯间规聚合

制备了 β 二酮类配体 [O ,O]的茂基二氯化钛配合物CpTi(dbm)Cl2 .实验证明 ,这类配合物在助催化剂甲基铝氧烷MAO作用下 ,可催化苯乙烯间规聚合 .显示较高的活性 (10 7× 10 5gPS molTi·h) .所得聚合物具有较高的间规度 .CpTi(dbm)Cl2 MAO体系催化活性随铝 钛比的增加呈上升而后衰减 ,当铝 钛比为 5 0 0左右时活性最高 ;聚合温度较高时会导致催化活性下降 .对聚合物进行了1 3C NMR表征     

单茂钛化合物/MAO/AlR_3均相催化体系合成sPS与aPP研究

先考察部分水解三甲基铝（ＴＭＡ）制备固体改性甲基铝氧烷（ｍ ＭＡＯ）时，反应物Ｈ２Ｏ和ＴＭＡ的摩尔比对固体产物ｍ ＭＡＯ中ＴＭＡ含量的影响；然后考察不同的钛化合物特别是茂钛化合物（ＬｎＴｉＸｎ′，ｎ＝１，２，ｎ′＝２，３）和ｍ ＭＡＯ组成的均相催化体系分别进行苯乙烯间规聚合和丙烯无规聚合的效果作比较．在此基础上分析以茂基三正丙氧基钛［ＣｐＴｉ（ＯＰｒｎ）３］为主催化剂，不同ＴＭＡ含量的ｍ ＭＡＯ为助催化剂，及外加各种烷基铝（ＡｌＲ３）所组成的催化体系中钛的氧化数，同时对苯乙烯间规聚合和丙烯无规聚合进行比较研究，从中发现活性中心钛的氧化数以Ｔｉ（Ⅲ）为主时有利于苯乙烯间规聚合，不利于丙烯无规聚合；而氧化数以Ｔｉ（Ⅳ）为主时则对丙烯无规聚合有利．苯乙烯间规聚合时，外加烷基铝可节省ＭＡＯ用量．     

茂钛催化剂的苯乙烯间规聚合

比较了几种庞钛化合物/甲基铝氧烷/三甲基铝均相催化剂的苯乙烯间规聚合,认为茂基三正丙氧基钛[CpTi(O－n－Pr)₃]是苯乙烯间规聚合的良好催化剂[催化效率：ω_ps·ω_Ti^-1=4×10⁴g·g^-1]．探索了催化剂浓度、单体浓度、聚合温度和时间对苯乙烯聚合的影响．聚合反应产物用佛丁酮萃取,沸丁酮不可溶级分大于95％,经¹³CNMR分析该级分为间规聚苯乙烯．     

单茂钛催化剂的丙烯无规聚合反应及其动力学研究

比较了不同钛化合物／甲基铝氧烷（ＭＡＯ）催化体系的丙烯无规聚合，催化活性次序为ＣｐＴｉ（ＯＲ）３＞ＣｐＴｉ（ＯＰｈ）３＞ＣｐＴｉＣｌ３＞Ｃｐ２ＴｉＣｌ２＞Ｔｉ（ＯＢｕ）４＞ＴｉＣｌ４＞Ｔｉ（ＯＢｕ）２Ｃｌ２，所得聚丙烯用沸庚烷抽提８ｈ，溶解９５％以上，可溶部分经１３Ｃ ＮＭＲ、ＷＡＤＸ、ＦＴＩＲ等分析证明为无规聚丙烯（ａＰＰ），是没有结晶性的弹性体．ＧＰＣ测出其分子量Ｍｗ＝８．０～１０．０×１０４，Ｍｗ／Ｍｎ≈２．０．探索了催化体系ＣｐＴｉ（Ｏ ｎ Ｐｒ）３／ＭＡＯ中钛的浓度、［Ａｌ］／［Ｔｉ］摩尔比，丙烯聚合压力，聚合温度和时间对丙烯聚合反应的影响．研究了该催化体系丙烯聚合反应动力学规律，表观聚合反应速率对催化剂浓度和单体压力（浓度）都呈一级反应关系，表观聚合速率常数ＫＰ＝２９２×１０５ｍｏｌ／Ｌ·ｈ（４０℃）．活化能ΔＥ＝－７．８８×１０３Ｊ·ｍｏｌ－１，碰撞因子Ａ＝１．４１×１０－４ｍｏｌ／Ｌ·ｈ．     

Synthesis and characterization of titanium tetraisocyanide complexes, [CpTi(CNXyl)4E], E = I,SnPh3, and SnMe3

Oxidation of [CpTi(CO)₄]^? by I₂, Ph₃SnCl, and Me₃SnCl in the presence of four equivalents of CNXyl, Xyl = 2,6-dimethylphenyl, affords unprecedented titanium tetraisocyanide complexes, [CpTi(CNXyl)₄E], E = I, SnPh₃, SnMe₃. These have been isolated and characterized by spectroscopic methods as well as single-crystal X-ray crystallography. A by-product of the iodine reaction was the Ti(III) complex, [CpTi(CNXyl)₂I₂], which was also characterized by X-ray crystallography.     

Mao based catalysts for syndiotactic polystyrene (sPS)

Several non-metallocene (Ti, Zr) and substituted mono-Cp titanium metallocenes have been tested in the presence of methylalumoxane (MAO) as catalyst for syndiospecific polymerization of styrene. Effect of substitutions on the titanium and Cp ligand, molar ratio of Al/Ti, TMA and temperature on activity, Mwt. and % sPS were studied. CpTi(OiPr)₃ gives a less active catalyst than Cp*Ti(OiPr)₃ and the resulting sPS is less stereoregular and of lower molecular weight.     

Synthesis, structures, and solution behavior of di- and trinuclear titanium(IV)--cyclophosphato complexes

The reaction of the cyclotetraphosphate ion (P(4)O(12)(4)(-)) with [CpTiCl(3)] (Cp = eta(5)-C(5)Me(5)) gives [(CpTi)(2)(P(4)O(12))(2)](2)(-) where the P(4)O(12) ligands adopt a saddle conformation, while that with [(CpTiCl)(3)(mu-O)(3)] leads to [(CpTi)(3)(mu-O)(3)(P(4)O(12))](-) containing a crown form P(4)O(12) ligand; both products feature their unique cage structures. On the other hand, the reactions of the cyclotriphosphate ion (P(3)O(9)(3)(-)) with [(CpTiCl(2))(2)(mu-O)] and [(CpTiCl)(3)(mu-O)(3)] afford [(CpTi)(2)(mu-O)(P(3)O(9))(2)](2)(-) and [(CpTi)(3)(mu-O)(3)Cl(P(3)O(9))](-), respectively, and in both cases the P(3)O(9) ligands bridge two titanium centers with an eta(2):eta(1) mode.     

Reactions of trichloro(cyclopentadienyl)titanium(IV) with 1,5-diarylthiocarbazones

Summary The synthesis and characterization of the complexes from the reactions of trichloro(cyclopentadienyl)titanium(IV) with 1,5-diarylthiocarbazones (aryl=phenyl,o-tolyl,o-chlorophenyl,p-tolyl,p-chlorophenyl, or 3,5-dimethylphenyl) are reported. They are of the types CpTi(HDz)Cl₂ and CpTi(HDz)₂Cl (Cp=cyclopentadienyl, HDz^–=the mono-anion of a 1,5-diarylthiocarbazone, H₂Dz). The compounds are nonelectrolytes in dimethylformamide (DMF). In solid state, the far i.r. spectra of CpTi(HDz)Cl₂ indicate the complexes to be dimeric, involving Cl-bridges.     

Monocyclopentadienyl titanium(IV) alkyl xanthate complexes

Titanium(IV) alkyl xanthates of the types CpTi(S₂COR)Cl₂, CpTi(S₂COR)₂Cl and CpTi(S₂COR)₃, where R = CH₃, C₂H₅, C₃H₇, C₄H₉ and C₅H₁₁, have been prepared by the reaction of monocyclopentadienyl titanium(IV) trichloride with potassium alkyl xanthates in anhydrous dichloromethane. Conductance and infrared studies suggest that these complexes are non-electrolytes in which all of the xanthate ligands are bidentate. Proton nmr spectra of these complexes indicate that there is rapid rotation of the cyclopentadienyl ring about the metal-ring axis and for the CpTi(S₂COR)₃ complexes non-equivalence of the alkylxanthate ligands was observed.     

包封多酸化合物的固体脂质纳米粒的合成及生物活性研究

The solid lipid nanoparticles encapsulated polyoxometalate K₆[γ-(CpTi)₂SiW₁₀O₃₈] (abbreviated as (CpTi)₂SiW₁₀ Cp=η⁵-C₅H₅) have been prepared and structurally characterized by elemental ananlysis, IR, UV spectroscopy and TEM. The result showed that the polyoxometalate retained the parent structure after being encapsulated and the encapsulation increased the antitumoral activity of the polyoxometalate.     

A comparative study on photoelectrochemical performance of TiO2 photoanodes enhanced by different polyoxometalates

Based on the incorporation of polyoxometalates (POMs) into TiO₂ film, the photoelectrochemical performance of POMs/TiO₂ anode was elucidated by comparative investigation on the electron transport and electron–hole recombination in POMs/TiO₂ anode. The photoelectrochemical performance of the POMs/TiO₂ anode was clearly dependent on the type and content of POMs. Compared to the TiO₂ anode, the POMs/TiO₂ anode with low POMs loadings (0.75%) displayed the enhanced photoelectrochemical performance, while the excessive content (7.5%) of POMs could almost cause a negative effect. Thus, POMs could act as either “shallow electron trap” or “deep electron trap” depending on the different types and contents of POMs. This study reveals that the introduction of POMs into TiO₂ anode could facilitate photogenerated electron transfer and reduce electron–hole recombination, which is urgently desired to develop advanced composite materials of POMs/TiO₂ for application in photoelectrochemical catalysis and solar cells.     

杂多阴离子柱撑水滑石的合成、热稳定性、酸碱性研究

采用水溶液中阴离子直接交换法合成了过渡金属单取代Keggin结构杂多阴离子SiW11M(H2O)O39^6^- (M=Mn^2^+, Fe^2^+, Co^2^+, Ni^2^+, Cu^2^+,Zn^2^+)柱撑水滑石。用元素分析、XRD和IR对产物的组成与结构进行了表征。XRD结果给出柱撑产物的底面间距达1.47nm。DTA结合不同温度下焙烧样品的XRD、IR研究表明, 柱撑水滑石在低于250℃时脱除物理吸附水和层间水; 在400~500℃之间脱除层上羟基, 形成一个无定形的混合氧化物状态; 在600℃以上无定形态结晶为晶态氧化物混合物。异丙醇探针反应表明, 柱撑水滑石具有高于水滑石前驱体和相应杂多酸盐的催化活性, 且同时存在酸碱两类催化活性中心, 但酸中心明显较强。     

(二苯甲酰甲烷基)(环戊二烯基)二氯化钛/MgCl2-SiO2/MAO中各组分对乙烯聚合的影响

研究开发了一种新型非茂负载乙烯聚合催化剂 CpTi(dbm)Cl2 MgCl2 SiO2 MAO ,并考察了该催化剂中各组分对乙烯聚合活性的影响 .结果表明 ,SiO2 不仅可以改善催化剂的流动性和分散性 ,还有益于提高催化活性 .MgCl2 对活性中心有一定化学改性作用 ;MgCl2 、SiO2 和CpTi(dbm)Cl2 的比例的变化对载体型催化剂的催化活性有一定影响作用 ;采用适量的MAO对复合载体MgCl2 SiO2 活化 ,能提高催化活性 .用ZnCl2 MAO对SiO2处理制成的复合载体催化剂CpTi(dbm)Cl2 MgCl2 ZnCl2 SiO2 MAO ,可以提高催化活性 ,“锌调”作用明显 ,随着锌化合物含量的增加 ,聚合物相对分子质量下降 ,相对分子质量分布加宽 ,并且其催化活性也增加 .     

磷钼酸/聚苯乙烯/聚乙烯醇电纺纤维膜的制备及性能

采用静电纺丝法制备了磷钼酸/聚苯乙烯(PS)/聚乙烯醇(PVA)复合纤维,并将其模压成膜.利用红外光谱(IR)、扫描电子显微镜(SEM)及X射线能谱(EDX)等对复合纤维及其膜的结构与形貌进行表征,并对复合纤维膜的光催化性能、力学性能及在水中稳定性进行测试.结果表明,在复合纤维中磷钼酸的Keggin结构得到保持.PS与PVA质量比为1∶1时,复合纤维形貌最佳,表面光滑,直径较小且分布均匀,复合纤维的直径随着磷钼酸含量的增加而减小.将磷钼酸固载于复合纤维膜上比直接使用具有更高的光催化活性,光照25 min后接近98%的甲基橙降解;复合纤维膜易于回收再利用,5次重复使用后,复合纤维膜没有破损,磷钼酸损失较少,光催化性能无明显下降.复合纤维膜的强度随磷钼酸含量的增加先增大后减小,韧性随PVA含量的增加而增大,随磷钼酸含量的增加而减小.     

Electrochemical-reduction-assisted Assembly of Pd NPs/Polyoxometalates/Graphene Ternary Nanocomposite and Its Electrocatalytic Performance toward Formic Acid Oxidation

A novel ternary nanocomposite, Pd nanoparticles(NPs)/polyoxometalates(POMs)/reduced graphene oxide(rGO), was prepared by a green, mild, electrochemical-reductionassisted assembly. It is worth noting that the Keggin-type POM acts as an electrocatalyst as well as a bridging molecule. During the reduction process, POMs transfer the electrons from the electrode to GO, leading to a deep reduction of GO and the content of oxygen-containing groups is decreased to around 6.1%. Meanwhile, the strong adsorption effect between the POM clusters and rGO nanosheets induces the spontaneous assembly of POM on r GO in a uniformly dispersed state, forming a nanocomposite. The ternary Pd NPs/POMs/rGO nanocomposite exhibits higher electrocatalytic activities, better electrochemical stability, and higher resistance to CO poisoning than the Pd/C catalyst towards the formic acid oxidation(FAOR). Especially, the Pd/PW_(12)/rGO exhibits the best electrocatalytic performance among three Pd/POMs/rGO composites(POMs = PW_(12), SiW_(12), PMo_(12)).     

基于杂多酸的负载离子液相催化在醇氧化中的应用

采用溶胶-凝胶法制备的离子液体功能化的二氧化硅对于杂多酸是一种可行的载体,三种商用杂多酸成功的负载在离子液体功能化的二氧化硅上作为醇氧化的催化剂.利用FTIR、XRD、XPS对该种负载离子液相催化剂进行了表征.基于磷钨酸的负载离子液相催化剂活性最好,高产率(大部分＞93%)的得到了相应的羰基化合物.且该催化剂经过简单的...     

Nanoscale polyoxometalate‐based inorganic/organic hybrids

The latest advances in the area of polyoxometalate (POM)‐based inorganic/organic hybrid materials prepared by self‐assembly, covalent modification, and supramolecular interactions are presented. This Review is composed of five sections and documents the effect of organic cations on the formation of novel POMs, surfactant encapsulated POM‐based hybrids, polymeric POM/organic hybrid materials, POMs‐containing ionic crystals, and covalently functionalized POMs. In addition to their role in the charge‐balancing, of anionic POMs, the crucial role of organic cations in the formation and functionalization of POM‐based hybrid materials is discussed. DOI 10.1002/tcr.201100002     

六钼酸盐有机胺杂化衍生物与SARS-CoV 3CLpro相互作用的分子动力学模拟

采用分子动力学模拟方法, 在分子水平上探讨六钼酸盐有机杂化衍生物潜在的抗SARS病毒活性. 3CLpro主蛋白酶是冠状病毒复制和转录过程中起关键作用的功能蛋白, 因此采用SARS-CoV 3CLpro作为靶标进行抗SARS病毒的药物设计. 使用Insight II软件包中的Biopolymer, Discover 3, Profile-3D和Affinity等模块, 研究 POMs/3CLpro相互作用的结合位点和作用性质. 研究其能量变化规律, 探讨了多酸化合物对SARS病毒可能的抑制机理. 研究结果表明, POMs与3CLpro在酶的催化活性位点处有较强的结合力. 形成的复合物主要以静电相互作用相结合, 氢键相互作用对复合物的相对稳定性有一定影响. 对于POMs/3CLpro复合物, 有机胺基团取代的POMs所带负电荷比未取代体系的高, 比3CLpro的结合能更高, 这与POMs的相关量子化学计算结果吻合.     

Synthesis of a New Polyoxometalate Loaded Stearic Acid Nanoparticles

The stearic acid nanoparticles loaded polyoxometalate K6[γ-(CpTi)2SiW10O38][(CpTi)2SiW10] have been prepared and structurally characterized by elemental analysis, IR spectra.The particle size was estimated by transition electron microscope and zatesizer instrument. The result showed that the polyoxometalate retained the parent structure after encapsulation by stearic acid nanoparticles.     

Mixed-sequence pyrrolidine-amide oligonucleotide mimics: Boc(Z) synthesis and DNA/RNA binding properties

Pyrrolidine-amide oligonucleotide mimics (POMs) exhibit promising properties for potential applications, including in vivo DNA and RNA targeting, diagnostics and bioanalysis. Before POMs can be evaluated in these applications it is first necessary to synthesise and establish the properties of fully modified oligomers, with biologically relevant mixed sequences. Accordingly, Boc-Z-protected thyminyl, adeninyl and cytosinyl POM monomers were prepared and used in the first successful solid phase synthesis of a mixed sequence POM, Lys-TCACAACTT-NH2. UV thermal denaturation studies revealed that the POM oligomer is capable of hybridising with sequence selectivity to both complementary parallel and antiparallel RNA and DNA strands. Whilst the duplex melting temperatures (Tm) were higher than the corresponding duplexes formed with isosequential PNA, DNA and RNA oligomers the rates of association/dissociation of the mixed sequence POM with DNA/RNA targets were noticeably slower.