Total syntheses of (+)-chloropuupehenone and (+)-chloropuupehenol and their analogues and evaluation of their bioactivities

Tetracyclic pyrans (+)-chloropuupehenone (1) and (+)-chloropuupehenol (5) and its C8-R-isomer (+)-3 were synthesized via a one-pot condensation of 1-chloro-2-lithio-3,5,6-tris(tert-butyldimethylsilyloxy)benzene (8) with (4aS,8aS)-3,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethylnaphthalene-1-carboxaldehyde (7). The major condensation product, (4aS,6aR,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (4), after desilylation provided tetracyclic pyran (+)-(4aS,6aR,12bS)-2H-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene-9,10-diol (3). At a dosage of 42 mg/rat over 8 h, pyran diol 3 inhibited the intestinal absorption of cholesterol by 71% in rats. Tetracyclic pyran 4 was also converted to o-quinone 28, which inhibited cholesteryl ester transfer protein (CETP) activity and L1210 leukemic cell viability with IC(50) values of 31 and 2.4 microM, respectively. Diol (+)-5 inhibited CETP activity with an IC(50) value of 16 microM. The minor condensation product, (4aS,6aS,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (6), was transformed into (+)-5 and (+)-1. A stepwise stereoselective synthesis of (+)-1 was also developed utilizing an oxyselenylation ring-closure reaction. The synthetic sequence also produced four biologically active naturally occurring drimanic sesquiterpenes, (+)-drimane-8alpha,11-diol (34), (-)-drimenol (38), (+)-albicanol (39), and (-)-albicanal (31) as intermediates.     

制备方法对钯-铈锆固溶体催化剂的结构与性能的影响

采用溶胶凝胶法制备了Pd掺杂型铈锆固溶体粉末.XRD和XPS分析结果表明,有部分Pd进入了固溶体的晶格,主要以PdO和PdO2的形态存在;900 ℃ 50 h的老化条件并没有使Pd和Ce的价态发生明显的变化;其催化性能主要取决于氧空位的数量和活性,与Pd负载型铈锆催化剂相比,表现出较好的热稳定性能.     

V2O5／TiO2催化剂的表面结构和酸碱性及氧化还原性

 研究了一系列锐钛矿担载的钒氧化物催化剂的表面性质．X射线衍射和Raman光谱表明，8％V2O5／TiO2催化剂上的V2O5处于单层分散状态．程序升温还原研究表明，单层分散的钒物种较易被还原，而形成多聚态和晶态后钒物种的还原温度升高．NH3吸附量热结果表明，在钒物种达到单层分散前，催化剂的表面酸性随钒担载量的增加而减弱，超过单层分散后，表面酸位的数目和强度基本不变．异丙醇脱氢／脱水反应结果表明，有O2时V2O5／TiO2催化剂显示出很强的氧化还原性，无O2时催化剂的脱水选择性较高．通过异丙醇的脱氢／脱水反应，将V2O5／TiO2催化剂的表面结构与其酸碱性和氧化还原性进行了初步的关联．     

Synthesis and electrochemical properties of amphiphilic crown ether langmuir-blodgett films [1]

4-Octadecanoylbenzo-15-crown-5 (I) and four 4-alkylbenzo-15-crown-5 ligands [4-XB15C5 where X =n-C₁₈H₃₇ (II), X =n-C₁₆H₃₃ (III), X =n-C₁₄H₂₉ (IV), and X =n-C₁₂H₂₅ (V)] have been synthesized. The -A isotherms ofI andII were systematically investigated. The results indicated that the Langmuir-Blodgett (LB) films have high stability where the ratios ofI/SA andII/SA were 1 : 1 and 1 : 10, respectively, with a 6.2 pH subphase. The LB films of the crown ethers were deposited onto graphite electrodes pretreated by immersing them in liquid wax. The peak current reached the maximum value when the electrode surface was modified with five layers of the amphiphilic crown ethers.     

Approaching the Lithiation Limit of MoS2 While Maintaining Its Layered Crystalline Structure to Improve Lithium Storage

MoS₂ holds great promise as high‐rate electrode for lithium‐ion batteries since its large interlayer can allow fast lithium diffusion in 3.0–1.0 V. However, the low theoretical capacity (167 mAh g^?1) limits its wide application. Here, by fine tuning the lithiation depth of MoS₂, we demonstrate that its parent layered structure can be preserved with expanded interlayers while cycling in 3.0–0.6 V. The deeper lithiation and maintained crystalline structure endows commercially micrometer‐sized MoS₂ with a capacity of 232 mAh g^?1 at 0.05 A g^?1 and circa 92 % capacity retention after 1000 cycles at 1.0 A g^?1. Moreover, the enlarged interlayers enable MoS₂ to release a capacity of 165 mAh g^?1 at 5.0 A g^?1, which is double the capacity obtained under 3.0–1.0 V at the same rate. Our strategy of controlling the lithiation depth of MoS₂ to avoid fracture ushers in new possibilities to enhance the lithium storage of layered transition‐metal dichalcogenides.     

Nanowire of WP as a High-Performance Anode Material for Sodium-Ion Batteries

The design and development of electrode materials with high specific capacity and long cycling life for sodium-ion batteries (SIBs) is still a critical challenge. In this communication, we report the development of tungsten phosphide (WP) nanowire on carbon cloth (WP/CC) as an anode for SIBs. The WP/CC exhibits superior sodium storage capability with 502 mA h g⁻¹ at 0.1 A g⁻¹. Moreover, this anode is capable of delivering a long lifespan at 2 A g⁻¹ with an excellent capacity retention of 99 % after 1000 cycles.     

铈钼氧化物表面氧性质和催化性能

在甲苯选择性氧化制苯甲醛反应中,Mo基氧化物是一类重要的催化剂[1]．通常的认识是反应物与催化剂表面晶格氧作用,并通过催化剂本身的还原和氧化的循环过程促使反应进行。生成产物．因此,催化剂表面不同氧物种的热脱附性能应与催化反应性能密切相关．对于Ce-Mo氧化物的TPD-MS研究,尚未见文献报导．为了能获得该方面的信息,本文应用程序升温脱附-质谱检测（TP-MS）联用技术,对Ce-Mo氧化物样品进行了表面氧TPD谱测定和动力学参量等计算,并试图与其催化性能进行关联．1实验部分1．1样品的制备和表征分别将一定质量的硝酸铈铵和仲…     

In/HZSM-5催化剂上CH4选择还原NO的研究: 反应条件对催化剂性能的影响

用浸渍法制备的In/HZSM-5催化剂在甲烷还原一氧化氮反应中显示了很高的活性,500℃时,氧化氮的转化率可达100%.过量氧气的存在并没有对催化剂的活性产生很大的影响,这可能与In/HZSM-5催化剂上甲烷选择还原一氧化氮的反应机理有关.随着反应气体空速的增大,氧化氮的转化率缓慢下降,同时,甲烷的转化率也缓慢下降.这说明还原剂甲烷的适度活化在本反应中起着关键作用.     

可紫外光固化的超支化聚硅氧烷合成及固化研究

同线型聚硅氧烷聚合物相比，超支化聚硅氧烷聚合物具有低粘度、高反应活性和良好的相容性等特点，其中以制备超支化的聚硅氧烷基硅氧烷和聚烷氧基硅氧烷为主．对于超支化聚硅氧烷主要是以ABx（X=2～6）（其中A为双键，B为硅氢键）型单体为原料，在氯铂酸或Pt／C的催化下，通过硅氢加成反应一步制备，最终聚合物的端基（B）为硅氢键，而双键则完全反应，此外也可通过含不同数目烷氧基硅烷的水解缩合制备超支化聚硅氧烷．     

温度及pH敏感的β-环糊精聚合物微球的合成及药物控制释放研究

以反相乳液聚合得到了β-CD聚合物微球,对β-CD微球进行氯乙酰化改性后,利用原子转移自由基聚合的方法把聚甲基丙烯酸N ,N 二甲氨基乙酯(PDMAEMA)接枝到β-CD微球上,从而得到了具有温度和pH响应性的β- CD聚合物微球.通过红外光谱、元素分析确定了PDMAEMA接枝的β- CD微球的结构,采用热台偏光显微镜直接观测到了β- CD微球的温度和pH敏感性.对模型药物染料木素(GNT)和苯丁酸氮芥(CLB )进行了控制释放研究,结果表明pH值可对微球的“内环境”起到“开 关”作用,从而可构筑出一种新型的药物控制释放体系.