N-对甲苯磺酰基-7-氮杂-双环[2.2.1]-2,5-庚二烯-2,3-二羧酸二甲酯光敏化电子转移异构反应研究

降冰片二烯及其衍生物是分子光化学贮存太阳能反应体系中研究较多的一类模型化合物^[1-4]。但是,从迄今报道的研究工作来看,大部分是关于7-位为碳原子的降冰片二烯衍生物。对于7-位为杂原子的衍生物的光异构化反应以及7-位杂原子对光异构化反应的影响还未见报道。     

咔唑-降冰片二烯二元化合物的合成及其分子内光敏异构化反应

降冰片二烯和四环烷之间的价键异构是太阳能贮存研究中最有希望的体系之一。太阳光的辐射一般大于300nm,而降冰片二烯本身的吸收在230nm 左右,无法直接吸收太阳光。为了解决这一矛盾,人们通常从两方面来研究,一方面,是在降冰片二烯上引     

降冰片二烯衍生物的光异构化 Ⅱ.2-萘胺甲酰基-2,5-[2.2.1]-双环庚二烯的光异构化

合成了降冰片二烯衍生物——2-萘胺甲酰基-2,5-[2.2.1]-双环庚二烯(B)。研究了它在太阳光直接照射下的光异构化反应。(?) 此外,还确定了化合物(B)和(C)的分子结构。它们都是文献中未曾报道过的新化合物。     

降冰片二烯衍生物的染料敏化电子转移光异构化反应的研究

降冰片二烯及其衍生物的光异构化反应已有广泛的研究,反应生成的四环烷衍生物是储能的重要化合物。由于降冰片二烯及其衍生物的吸收波长大多都在紫外区,所以,为了有效地实现太阳能的储存和转换,人们除了利用直接光异物化的途径外,更感兴趣的是用敏化光异构化的办法实现这种转换。到目前为止,已报道的降冰片二烯衍生物的敏化光异构化反应大多是通过较高三重态能量的敏化剂的三重态能量传递位降冰片二烯衍生物发生异构     

高分子体系中降冰片二烯的光异构化反应

本文合成了降冰片二烯和咔唑为侧基的甲基丙烯酸酯共聚物,并与仅带有降冰片二烯侧基的聚甲基丙烯酸酯进行了光异构化反应的对比研究。实验结果表明,当入射光波长小于350nm时,两种降冰片二烯聚合物均发生了光异构化反应;当入射光波长大于350nm时,只有共聚物的降冰片二烯侧基能够异构化为相应的四环烷。利用荧光猝灭实验及化学诱导动态核极化(CIDNP)等研究了咔唑的敏化机理,利用三氟乙酸作催化剂实现了四环烷的反向异构化。     

降冰片二烯-甾体-二苯酮两元化合物的合成及其光化学研究

本文合成了一个新的降冰片二烯-甾体-二苯酮两元化合物(NBD-S-BP), 并研究了它的光化学反应。NBD-S-BP在λ>350nm光的照射下, BP基团吸收光能, 系间窜越到三线态后将能量传递到NBD基团并使后者异构化为四环烷, 量子效率为21%。     

芳醚树枝形聚合物的合成及分子内光敏异构化反应研究

利用收敛法合成了一代到四代外围带有二苯酮、核心带有降冰片二烯的芳醚树枝形聚合物, 初步研究了这些化合物的分子内光敏异构化反应. 以波长大于350 nm的光选择激发外围的二苯酮官能团引起核心处降冰片二烯基团异构化为四环烷, 随着代数的增长, 光敏异构化反应的速率逐渐加快.     

四环烷-甾体-二苯甲酰基甲烷硼氟络合物分子内电子转移诱导光敏异构化反应的研究

本文设计并合成了四环烷-甾体-二苯甲酰基甲烷硼氟络合物组成的二元化合物新体系(QC-S-BF).利用稳态光谱和时间分辨光谱,对其光物理行为和光化学反应进行了研究。结果表明:此二元化合物分子内BF基团的荧光被远距离的QC基团有效地猝灭,选择激发BF基团,可导致四环烷到降冰片二烯的异构化,此过程是通过分子内单重态电子转移生成QC正离子,该正离子异构化生成降冰片二烯正离子,然后经电子复合实现其分子内光敏异构化反应。通过稳态和时间分辨技术,测得此分子内远距离单重态电子转移和QC正离子异构化的效率分别为0.25和0.23.这项工作表明:当给体与受体距离为19Å时,二者之间仍能发生有效的电子转移,这种电子转移过程是通过“键”进行的。     

咔唑-降冰片二烯二元化合物的合成及其分子内光敏异构化反应

在本文的工作中,我们合成了咔唑与降冰片二烯二甲酸二甲酯以不同链长的碳链相连的二元化合物，讨论了不同链长化合物的分子构象,并首次实现了分子内的电子转移光异构化反应,为进一步寻找更有效的光异构化反应体系探索了一条新的道路。     

异构化合成顺-5-降冰片烯-外-2,3-二酸酐的研究

以解聚的环戊二烯单体与马来酸酐为原料通过Diels-Alder反应、异构化以及重结晶制备高纯度的顺-5-降冰片烯-外(exo)-2,3-二酸酐.主要对顺-5-降冰片烯-内(endo)-2,3-二酸酐的异构化进行详细研究,对酸促进异构化、碱促进异构化及加热异构化进行比较.通过对加热异构化的溶剂、反应时间、底物浓度进行优化,得出了一种较好的异构化方法:以邻苯二甲醚为溶剂加热异构化可得到高纯度的顺-5-降冰片烯-外-2,3-二酸酐,总产率为66.5%.     

合成双酚AF的新方法

由六氟丙酮三水合物和苯胺,经缩合、重氮化、水解、Friedel-Crafts烷基化等4步反应在常压下合成了双酚 AF。首先,以五氧化二铌为催化剂,在 n (HFA•3H₂O) : n (aniline) : n (Nb₂O₅) = 2 : 1 : 0.1,回流 6 h 条件下,合成出中间体（Ⅰ）,收率高达96.3%。然后在重氮化温度为 ﹣2 ～ 2 ℃,硫酸质量分数为 14.7%,n (Ⅰ) : n (H₂SO₄) : n (NaNO₂) = 1 : 4.1 : 1.1,及水解时硫酸质量分数为 50%,n (H₂SO₄) : n (Ⅰ) = 11.0 : 1、108～112 ℃反应 1.5 ～ 2 h 的优化条件下,化合物Ⅰ经重氮化、水解后以 92.7%的高收率得到中间体 2-（4-羟基苯）六氟异丙醇（Ⅱ）;再在甲磺酸存在下,化合物Ⅱ与苯酚经Friedel-Crafts烷基化反应以 72.4% 的收率合成了目标产物双酚 AF（Ⅲ）,总收率为 64.6%（以苯胺为基准计算）。     

Syntheses of new model compounds related to an antigenic epitope from Bupleurum falcatum L. and their distributions in various ganglioside-phospholipid monolayers

6-N-[2-(Tetradecyl)hexadecanamido]hexyl beta-D-glucopyranosyluronic acid-(1-->6)-beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranoside (1) and its clustering compound (2) carrying a tetravalent sugar unit, which are new model compounds related to a major antigenic epitope from antiulcer pectic polysaccharide of Bupleurum falcatum L., were synthesized and the distributions of 1 and 2 in mixed ganglioside (GM1, GD1a or GT1b)/phospholipid (DPPC) monolayers were observed using atomic force microscopy (AFM). AFM images showed that 1 was distributed in the GM1, GD1a and GT1b region of the mixed monolayers, in which 1 was miscible with GD1a. Specific distribution of 1 was observed in the mixed GM1/DPPC monolayer. Compound 2 was miscible with GM1, while 2 formed associations with GD1a and GT1b in the mixed monolayers. The distribution mode of 1 and 2 was different among the mixed ganglioside/DPPC monolayers.     

邻羟基萘甲醛缩对二甲氨基苯甲酰腙的合成及其对锌离子的识别

设计并合成了用于识别锌离子的荧光传感分子——2-羟基-1-萘甲醛缩-4-二甲氨基苯甲酰腙(1),其结构经1H NMR,IR和MS表征。利用荧光光谱研究了在乙腈中1对过渡金属离子(Zn2+,Cd2+,Cu2+,Hg2+,Pb2+和N i2+)的识别能力。结果表明:1表现出对Zn2+的良好选择性,Zn2+的加入导致1的长波长荧光增强449倍。Job曲线确定1与Zn2+形成1∶1型配合物。     

Click-dendronized poly(amide-triazole)s--effect of dendron size and polymer backbone symmetry on self-assembling and gelation properties

Nine dendronized poly(amide-triazole)s 2-Gm Gn (m=1-3, n=1-3), were prepared by the 1:1 copolymerization between AA-type dendritic diazides 4-Gm (m=1-3) and BB-type dendritic diacetylenes 5-Gn (n=1-3) under the copper(I)-mediated click coupling conditions. The degree of polymerization value of the polymers was found to range from 15-50, and decreased with increasing size of the dendron, suggesting steric hindrance had a retardation role on the copolymerization efficiency. Based on FT-IR and (1)H NMR studies, it was found that significantly strong, interchain hydrogen bonding between the amide units was present in the solution state after copolymerization, whereas the monomers 4-Gm and 5-Gn were devoid of any intermolecular hydrogen-bonding interaction. Hence a positive allosteric hydrogen-bonding effect was observed after polymerization, and could be rationalized by the zip effect. The strength of the interchain association in polymers 2-Gm Gn was found to decrease with increasing size of the dendron (i.e., 2-G1 G1>2-G1 G2>2-G2 G1≈2-G2 G2>2-G1 G3≈2-G3 G1>2-G2 G3≈2-G3 G2>2-G3 G3). Among the nine polymers, only 2-G1 G2 and 2-G2 G1 were good organogelators for aromatic solvents, while the 2-G2 G2 polymer, bearing the closest structural resemblance to the previously reported organogelator 1-G2 prepared from the polymerization of AB-type monomers, was devoid of gelating power. Careful analysis of structures of the present polymer series 2-Gm Gn and the previously reported series 1-Gn suggested that the polymer backbone symmetry played a subtle role in controlling their self-assembling and gelating properties.     

Solvent effect on ion-pair extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion using alcohols and 1-octanol/octane mixed solvents.

Extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion was carried out using 14 kinds of alcohols and 1-octanol/octane mixed solvents as a solvent at 25 degrees C. Alcohols are 1-pentanol, 1-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 2-octanol, 3-octanol, 1-nonanol, 2-nonanol, 3-nonanol, 5-nonanol and 1-decanol. Among them, 1-octanol was found to be extremely high in extractability for 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with hydroxonium cation. The extraction equilibrium for the systems using 1-octanol/octane mixed solvents was analyzed in detail in order to examine the extraction mechanism for these extraction systems. 2-(2-Pyridylazo)-1-naphthol-4-sulfonate anion was found to be extracted with the hydroxonium ion solvated by three 1-octanol molecules as an ion-pair. The extraction and partition constants of the ion-pair of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion were estimated in the 1-octanol/octane mixed solvent systems.     

Dynamic Ring-chain Equilibrium of Nucleophilic Thiol-yne “Click” Polyaddition for Recyclable Poly(dithioacetal)s

We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols. Four poly(dithioacetal)s(P1-P4) were prepared via the base-catalyzed thiol-yne "click" polyaddition of two dithiols(1,4-butanedithiol(4 S) and 1,5-pentanedithiol(5 S)) and two alkynones(3-butyn-2-one(Y1) and 1-phenyl-2-propyn-1-one(Y2)) at high concentrations. We systematically investigated the base-catalyzed polymerization of 4 S and Y1(for polymer P1) under dif...     

Monomer-isomerization polymerization. XIX. Monomer-isomerization copolymerizations of methylbutenes and 2-butene with Ziegler-Natta catalyst

The copolymerization of 3-methyl-1-butene (3M1B), 2-methyl-2-butene (2M2B), or 2-methyl-1-butene (2M1B) with trans-2-butene (2B) was attempted in the presence of a Ziegler-Natta catalyst. It was found the 3M1B underwent monomer-isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1-butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl₃–(C₂H₅)₃Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B-2B system was much higher than that in the 3M1B-1B system. However, 2M2B and 2M1B did not undergo monomer-isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.     

不对称Schiff碱镍(Ⅱ)配合物的合成及其晶体结构

合成了3个具有不对称结构的Schiff碱配体H2Ln(n=1、2、3)。H2L1由乙酰丙酮、乙二胺和水杨醛缩合作用得到,H2L2由乙酰丙酮、(1R,2R)-环己二胺和水杨醛缩合作用得到,H2L3由苯甲酰丙酮、乙二胺和水杨醛缩合作用得到,每个反应中3个反应物的物质的量之比均为1∶1∶1。配体H2Ln分别与Ni(OAc)2.4H2O进行配位反应得到3个单核Ni(Ⅱ)配合物1,2和3。分别采用1H NMR、FTIR和元素分析对化合物进行了表征,并通过X-射线单晶衍射技术测定了3个配合物的晶体结构。     

Pyruvate dehydrogenase kinase 1 and 2 deficiency reduces high-fat diet-induced hypertrophic obesity and inhibits the differentiation of preadipocytes into mature adipocytes

Obesity is now recognized as a disease. This study revealed a novel role for pyruvate dehydrogenase kinase (PDK) in diet-induced hypertrophic obesity. Mice with global or adipose tissue-specific PDK2 deficiency were protected against diet-induced obesity. The weight of adipose tissues and the size of adipocytes were reduced. Adipocyte-specific PDK2 deficiency slightly increased insulin sensitivity in HFD-fed mice. In studies with 3T3-L1 preadipocytes, PDK2 and PDK1 expression was strongly increased during adipogenesis. Evidence was found for epigenetic induction of both PDK1 and PDK2. Gain- and loss-of-function studies with 3T3-L1 cells revealed a critical role for PDK1/2 in adipocyte differentiation and lipid accumulation. PDK1/2 induction during differentiation was also accompanied by increased expression of hypoxia-inducible factor-1α (HIF1α) and enhanced lactate production, both of which were absent in the context of PDK1/2 deficiency. Exogenous lactate supplementation increased the stability of HIF1α and promoted adipogenesis. PDK1/2 overexpression-mediated adipogenesis was abolished by HIF1α inhibition, suggesting a role for the PDK-lactate-HIF1α axis during adipogenesis. In human adipose tissue, the expression of PDK1/2 was positively correlated with that of the adipogenic marker PPARγ and inversely correlated with obesity. Similarly, PDK1/2 expression in mouse adipose tissue was decreased by chronic high-fat diet feeding. We conclude that PDK1 and 2 are novel regulators of adipogenesis that play critical roles in obesity.Subject terms: Mechanisms of disease, Obesity     

Interactions of cholesterol with cyclodextrins in aqueous solution

The interaction of cholesterol with several cyclodextrins (CDs) was investigated in water using solubility method. It was found that heptakis (2,6-di-O-methyl)-beta-CD (DOM-beta-CD) forms two types of soluble complex, with molar ratios of 1 : 1 and 1 : 2 (cholesterol : DOM-beta-CD), and neither a soluble nor insoluble complex is formed between cholesterol and alpha-CD, beta-CD, and gamma-CD, although a minor soluble complex formation was observed between cholesterol and 2-hydroxylpropyl-beta-CD. The thermodynamic parameters for 1 : 1 and 1 : 2 complex formation of cholesterol with DOM-beta-CD obtained from the changes in K with temperature are as follows: DeltaG degrees (1 : 1)=-11.6 kJ/mol at 25 degrees C (K(1 : 1)=1.09x10(2) M(-1)); DeltaH degrees (1 : 1)=-3.38 kJ/mol; TDeltaS degrees (1 : 1)=8.25 kJ/mol; DeltaG degrees (1 : 2)=-27.1 kJ/mol at 25 degrees C (K(1 : 2)=5.68x10(4) M(-1)); DeltaH degrees (1 : 2)=-3.96 kJ/mol; and TDeltaS degrees (1 : 2)=23.2 kJ/mol. The formation of the 1 : 2 complex occurred much more easily than that of the 1 : 1 complex. The driving force for 1 : 1 and 1 : 2 complex formation was considered to be mainly hydrophobic interaction. Also, based on the measurements of proton nuclear magnetic resonance spectra and studies with Corey-Pauling-Koltun atomic models, the probable structutures of the 1 : 2 complex were estimated.