竹红菌素在DMF—H2O混合体系中的电化学研究

本文研究了竹红菌素ＨＡ，ＨＢ以及１３－ＳＯ３Ｎａ－ＤＤＨＡ在ＤＭＦ－Ｈ２Ｏ（体积分数ψ＝１）混合体系中的电化学氧化还原性质，结果表明，它们都为两步单电子还原过程，反应机理为：油 ＨＡ，ＨＢ：ＨＡ（ＨＢ）＋ｅ＋Ｈ＾＋－ＨＡ（ＨＢＨ）＋ｅ－ＨＡＨ，水溶性１３－ＳＯ３Ｎａ－ＤＤＨＡ：（第一步）１３－ＳＯ３Ｎａ－ＤＤＨＡ＋ｅ－１３－ＳＯ３ＮａＤＤＨＡ，（质子化）１３－ＳＯ３Ｎａ－ＤＤＨＡ＋Ｈ＾＋－１３－Ｓ     

竹红菌甲素衍生物13－SO_3Na－DDHA电化学及光诱导还原的研究

本工作研究了化合物１３－ＳＯ＿３Ｎａ－ＤＤＨＡ在不同ｐＨ的缓冲溶液中的电化学氧化还原行为．实验证明：化合物中羰基的还原电位与ｐＨ之间存在线性关系，其直线的斜率为６０ｍＶ／ｐＨ．并证明了此过程为一步两电子、两质子还原过程：Ｑ＋２Ｈ￣＋＋２ｅ＝ＱＨ＿２．ＤＭＦ作为非质子溶剂，具有很好的稳定自由基的作用．向缓冲溶液中加入ＤＭＦ后，化合物１３－ＳＯ＿３Ｎａ－ＤＤＨＡ为两步单电子还原过程，相应溶液中的光诱导电子转移吸收光谱证实了以上电化学的结果．     

竹红菌甲素衍生物13—SO3Na—DDHA电化学及光诱导还原的研究

本工作研究了化合物１３－ＳＯ３Ｎａ－ＤＤＨＡ在不同ｐＨ的缓冲溶液中的电化学氧化还原行为。实验证明：化合物中羰基的还原电位与ｐＨ之间存在线性关系，其直线的斜率为６０ｍＶ／ｐＨ。并证明了此过程为一步两电子、两质子还原过程：Ｑ＋２Ｈ＾＋＋２ｅ＝ＱＨ２．ＤＭＦ作为非质子溶剂，具有很好的稳定自由基的作用。向缓冲溶液中加入ＤＭＦ后，化合物１３－ＳＯ３Ｎａ－ＤＤＨＡ为两步单电子还原过程，相应溶液中的光诱导电子转     

顺、反异构钼硫簇合物〔(C_2H_5)_4N〕_2〔Mo_2S_4(SCH_2CH_2S)_2〕的合成、结构和性质研究

用（ＮＨ４）２ＭｏＳ４，ＣｏＣｌ２，ＮｉＣｌ２，ＨＳＣＨ２ＣＨ２ＳＨ和Ｅｔ４ＮＢｒ在ＣＨ３ＯＨＣＨ３ＯＮａ溶液中反应，得到了顺（Ａ），反（Ｂ）异构体的原子簇化合物［（Ｃ２Ｈ５）４Ｎ］２［Ｍｏ２Ｓ４（ＳＣＨ２ＣＨ２Ｓ）２］的晶体。用Ｘ—射线单晶衍射法测定了顺、反异构体簇合物Ａ和Ｂ晶体结构，其晶胞参数Ａ为ａ＝２．６０４４（２）ｎｍ，ｂ＝１．９８８６（２）ｎｍ，Ｃ＝２．６３０２（Ｉ）ｎｍ，Ｖ＝１３．５８６ｎｍ３，β＝９３．３３°（２）；Ｂ为ａ＝１．０４４（２）ｎｍ，ｂ＝１．４１５８（２）ｎｍ，Ｃ＝１．１４１７（２）ｎｍ，Ｖ＝１．６３８ｎｍ３，β＝１００．４７°，经块距阵最小二乘法修正最终得偏离因子Ｒ＝０．０８８（Ａ），Ｒ＝０．０８９（Ｂ）。同时还对簇合物的红外光谱和紫外可见光谱也进行了研究。     

耐磨Ni－SiC复合电镀及其应用

含ＳｉＣ最高达１１％的Ｎｉ－ＳｉＣ复合镀层的镀液配方及操作条件为：Ｎｉ（ＳＯ_３．ＮＨ_２）_２·４Ｈ_２Ｏ４１０，ＮｉＣｌ_２·６Ｈ_２Ｏ１０，Ｈ_３ＢＯ_３５０，ＯＰ－１００．４及ＳｉＣ（３μｍ）２０－１２０ｇ／Ｌ，ｐＨ４，５５±２℃，５Ａ／ｄｍ￣２，需搅拌．     

溶胶—凝胶法合成了BaAl2Si2O8超细粉末的研究

以Ｂａ（ＯＨ）２．８Ｈ２Ｏ，Ａｌ（ＮＯ３）３．９Ｈ２Ｏ，ＴＥＯＳ为原料，采用溶胶－凝胶法制备ＢａＯ－Ａｌ２Ｏ３－ＳｉＯ２三元系粉末，研究了不同因素对生成稳定溶胶和胶化时间的影响，用ＴＧ－ＤＴＡ，ＸＲＤ研究了溶胶－凝胶的热处理过程，用ＴＥＭ观察了粉体的粒径。     

核交换法对禾草类木素质结构的研究

本文采用该交换法对麦草粉，Ｎａ２ＳＯ３－ＨＣＨＯ－ＡＱ（ＳＦＰ－ＡＱ）浆，ＮａＯＨ－Ｎａ２ＳＯ３－ＡＱ（ＡＳＰ－ＡＱ）浆和ＮａＯＨ－ＡＱ（ＡＰ－ＡＱ）浆中残余木质素的化学结构特性进行了研究。通过核交换法结合硝基苯氧化反应，测定麦草原本木质素和浆中残余木质素的各类型酚核的数量，结果表明麦草原木木质素主要由２５．３５ｍｏｌ％非缩聚Ｇ单元，１７．６０ｍｏｌ％非缩聚Ｓ单元和５７．０５ｍｏｌ％的缩聚Ｇ单元所     

A3钢表面有机膦合钼聚多酸盐转化膜的研究

由Ｎａ２ＭｏＯ４·２Ｈ２Ｏ和Ｎａ２ＨＥＤＰ·５Ｈ２Ｏ合成了有机膦合钼聚多酸盐Ｎａ８［（ＨＥＤＰ）２Ｍｏ５Ｏ２１］·５Ｈ２Ｏ。用Ｎａ８［（ＨＥＤＰ）２Ｍｏ５Ｏ２１］·５Ｈ２Ｏ的溶液处理Ａ３钢，获得了具有一定耐蚀性的黄色转化膜，适宜的工艺条件为：浓度１６ｇ·Ｌ－１，ｐＨ３．５，温度５０℃，时间８０ｓ。本文还报告了膜层的ＸＰＳ和ＡＥＳ分析结果。     

镧系金属化合物催化苯乙烯和双烯烃的共聚──苯乙烯和异戊二烯共聚合制备高顺式－1，4嵌段共聚物

采用稀土催化体系Ｎｄ（Ｆ_３ＣＯ_２）_３－ＢｒＣ_５Ｈ_（１１）－Ｒ_ｍＡｌＨ_（３－ｍ）（Ｎｄ－Ｂｒ－Ａｌ），以甲苯为溶剂，在５０℃恒温水浴中进行苯乙烯（Ｓｔ）和异戊二烯（Ｉｐ）共聚合。结果表明，由Ａｌ（Ｏｃｔ）－３组成的催化体系可制备以顺式－１，４结构为主的共聚物；在后者组成的催化体系中，当Ａｌ／Ｎｄ＝５（摩尔比，下同），Ｂｒ／Ｎｄ＝５时，聚合活性最高。经ＩＲ，ＮＭＲ检测表征了共聚物的微观结构。同时，用π－烯丙基型配位机理和返扣配位机理对实验结果进行了定性解释。     

甲醇胺化有关产品的汽－液平衡测定

本文测定了与甲醇胺化产物有关的ＮＨ_３－ＣＨ_３ＯＨ，ＮＨ_３－二甲胺（ＤＭＡ），ＮＨ_３－一甲胺（ＭＭＡ），ＮＨ_３－Ｈ_２Ｏ，ＤＭＡ－ＣＨ_３ＯＨ，ＤＭＡ－Ｈ_２Ｏ，ＭＭＡ－ＣＨ_３ＯＨ，ＭＭＡ－Ｈ_２Ｏ和ＭＭＡ－三甲胺（ＴＭＡ）九个二元系在２０，３０，４０，５０，６０，７０，８０，９０，１００和１２０℃下的总压Ｐ和汽液总组成数据，用间接推算法计算了等温汽－液相平衡数据，给出了以实验数据拟合所得Ｗｉｌｓｏｎ参数Λ_（１２）和Λ_（２１），随温度变化关联式的常数。对所用仪器精度进行的误差分析表明，测定的最大相对误差为１．７％。     

竹红菌乙素的制备

竹红菌乙素是光敏性化合物,但在竹红菌中含量低,且难分离提纯。用重结晶方法从竹红菌中分离提纯竹红菌甲素,在碱的催化下竹红菌甲素脱水生成乙素,并用紫外分光光度计分析转化率,用1HNMR和13CNMR确定其结构是竹红菌乙素。     

Evidence for the Formation of a Radical‐Mediated Flavin‐N5 Covalent Intermediate

The redox‐neutral reaction catalyzed by 2‐haloacrylate hydratase (2‐HAH) leads to the conversion of 2‐chloroacrylate to pyruvate. Previous mechanistic studies demonstrated the formation of a flavin‐iminium ion as an important intermediate in the 2‐HAH catalytic cycle. Time‐resolved flavin absorbance studies were performed in this study, and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration‐dependent manner. These data are consistent with the flavin iminium intermediate occurring by radical recombination.     

New long-wavelength ethanolamino-substituted hypocrellin: photodynamic activity and toxicity to MGC803 cancer cell

To improve hydrophilicity and photoactivity of the new type of therapeutic agent, hypocrellin, a novel long-wavelength ethanolamino-substituted hypocrellin B (EAHB) was synthesized and its molecular structure was characterized by IR, NMR, MS, and UV–vis spectrometers, and EAHB had strong absorption at the phototherapeutic window (600–900 nm). Illumination of deoxygenated DMSO solution containing EAHB generated a strong electron paramagnetic resonance (EPR) signal, which was assigned to the semiquinone anion radical of EAHB (EAHB⁻). Absorption measurements displayed that the absorptive bands at 632 and 565 nm (shoulder) arose from the semiquinone anion radical (EAHB⁻) and the absorptive bands at 519 and 450 nm (shoulder) belonged to hydroquinone (EAHBH₂), which were formed via the decay of EAHB⁻ in water-contained solution. Superoxide anion radical (O₂⁻) was produced via electron transfer from EAHB⁻ (the precursor) to ground state oxygen. The presence of NADH, a bio-electron donor, significantly enhanced production of EAHB⁻ and O₂⁻. Singlet oxygen O₂ (¹Δ_g) could be produced via energy transfer from triplet EAHB to ground state oxygen molecules. The quantum yield of O₂ (¹Δ_g) and the relative quantum yield of O₂⁻ of EAHB were 0.15 and 0.76, respectively, with the parent compound hypocrellin B (HB) as the standard. It was inferred that Type I pathway was possibly a major photodynamic mechanism of EAHB. The study on photobiological action of EAHB on MGC803 cancer cells revealed that EAHB kept the same good phototoxic ability as HB but reduced 4 times cytotoxicity than HB, and also its photopotentiation factor increased 4-folds.     

阳离子P（BA—St—MBDM）共聚物乳液的合成及其抗静电性能

以丙烯酸丁酯（ＢＡ）、苯乙烯（Ｓｔ）和甲基丙烯酰氧乙基，二甲基，丁基溴化铵盐（简称ＭＢＤＭ、（ＣＨ２＝ＣＣＨ３－ＣＯＯＣＨ２Ｎ（ＣＨ３）２－ｎＣ４Ｈ９）＾＋Ｂｒ＾－）为共聚单体，Ｎ－甲基－Ｎ－十六烷基吗啉硫酸甲酯盐作乳化剂进行自由基型乳液聚合，研究了影响聚合速度、共聚物［η］和乳液稳定性的因素，合成了一系列稳定的阳离子共聚物乳液。所得乳液经稀释后对不同织物进行处理，处理后的织物具有良好的抗静电性和     

树皮酚类制备油田钻井液添加剂的研究

研究了兴安落叶松树皮经碱性磺化浸提 (15 0～ 180℃ ,3～ 6h)后 ,所得酚类磺化物再经络合(70～ 90℃ ,30～ 10 0min)、偶合 (70～ 10 0℃ ,1～ 5h)、缩合 (70～ 10 0℃ ,1～ 6h)、交联 (5 0～ 6 0℃ ,30～ 90min)多步化学改性 ,制备聚合物钻井液添加剂的新方法。所得添加剂中相对分子质量在5 0 0 0以上级分的摩尔分数 >80 % ,其分子上含有 3种亲水基团 :w(—SO3H) =13.4% ,w(—COOH)=8.2 6 % ,w(Ph—OH) =0 .96 % ;该添加剂在黏土颗粒表面发生吸附包被的摩尔分数为 93.9% ,在聚合物钻井液中的添加量为 0 .0 1kg/m3 时 ,降黏率和降滤失率分别为 6 5 .8%和 42 .9%。     

Ab Initio Calculation of BN Generation from Boron and Nitrogen Oxides

Boron Nitride (BN) is one of the products produced in the burning of boron‐containing propellant. A possible reaction mechanism for the reactions of boron and nitrogen oxides (NO, NO₂, N₂O) has been studied using the G2MP2 method. The BN product can be formed in the reactions of B(⁴P) with NO, NO₂ and N₂O. Among these three reactions, B(⁴P)+NO₂ and B(⁴P)+N₂O are 181.42 kJ/mol and 160.92 kJ/mol more‐exothermic than the B(⁴P)+NO reaction. The barrier heights from intermediates to transition states are 64.85 kJ/mol and 111.75 kJ/mol for B(⁴P)+NO₂ and B(⁴P)+N₂O, respectively. However, in the reaction B(⁴P)+NO , the transition from intermediate to product (IM3→BN+O) is very endothermic by 420.70 kJ/mol. So B(⁴P)+ N₂O→BN+NO and B(⁴P)+NO₂→BN+O₂ are more likely reactions to generate BN than B(⁴P)+NO→BN+O.     

Studies on polyurethanes and polyurethane–ureas derived from divalent metal salts of mono(hydroxybutyl) hexolate

Divalent metal salts of mono(hydroxybutyl)hexolate [M(HBH)₂), M=Ca²⁺, Mn²⁺or Pb²⁺] were synthesized by the reaction of 1,4‐butanediol, 5,6,7,8,10,10‐hexachloro‐3a,4,4a,5,8,8a,9,9a‐octahydro‐5,8‐methanonaphtho‐[2,3‐C]‐furan‐1,3‐dione and divalent metal acetates. Hexamethylene bis [N′‐(1‐hydroxy‐2‐methyl‐prop‐2‐yl)urea] (HBHMPU) and tolylene 2,4‐bis[N ′‐(1‐hydroxy‐2‐methyl‐prop‐2‐yl)urea] (TBHMPU) were synthesized by reacting 2‐amino‐2‐methyl‐propan‐1‐ol with hexamethylene diisocyanate (HMDI) and tolylene 2,4‐diisocyanate (TDI), respectively, in toluene solvent. Flame‐retardant metal‐containing polyurethanes were synthesized by the solution polymerization of HMDI with M(HBH)₂ and the polyurethane–ureas by reacting HMDI with 1:1 mixture of M(HBH)₂ and HBHMPU or TBHMPU, respectively, in DMSO as solvent. The polymers have been characterized by elemental analysis, solubility, viscosity and IR and ¹H NMR spectroscopy. The thermal stability of the polymers has been studied by thermogravimetry. The flame‐retardant property of the polymers has been investigated by measuring limiting oxygen index values. © 2000 Society of Chemical Industry     

水扬酸镍的合成表征及结构分析

用流变相反应法合成了Ni(OH)Sal·H2 O和Ni2 (OH) 2 Sal2 ·H2 O。通过元素分析、TG、IR、XRD和磁矩对其结构进行了分析。结果表明两个配合物都属于单斜晶系 ,其晶胞参数为 ,Ni(OH)Sal·H2 O∶a =13.1179,b =11.36 41,c =9.5 6 0 5 ,β =92 .96 2 ,V =14 2 3.31(97) 3,Z =7,Dcalcd .=1.885 g/cm3,Dexpt=1.85 8g/cm3;Ni2 (OH) 2 Sal2 ·H2 O :a =13.12 17,b =11.35 80 ,c =9.5 5 2 2 ,β =92 .978 ,V =14 2 1.72 (95 ) 3,Z =4 ,Dcalc=2 .0 73g/cm3,Dexp=2 .0 0 0 g/cm3。     

Understanding hydrogen atom transfer: from bond strengths to Marcus theory

Hydrogen atom transfer (HAT), a key step in many chemical, environmental, and biological processes, is one of the fundamental chemical reactions: A-H + B → A + H-B. Traditional HAT involves p-block radicals such as tert-BuO(?) abstracting H(?) from organic molecules. More recently, the recognition that transition metal species undergo HAT has led to a broader perspective, with HAT viewed as a type of proton-coupled electron transfer (PCET). When transition metal complexes oxidize substrates by removing H(?) (e(-) + H(+)), typically the electron transfers to the metal and the proton to a ligand. Examples with iron-imidazolinate, vanadium-oxo, and many other complexes are discussed. Although these complexes may not "look like" main group radicals, they have the same pattern of reactivity. For instance, their HAT rate constants parallel the A-H bond strengths within a series of similar reactions. Like main group radicals, they abstract H(?) much faster from O-H bonds than from C-H bonds of the same strength, showing that driving force is not the only determinant of reactivity. This Account describes our development of a conceptual framework for HAT with a Marcus theory approach. In the simplest model, the cross relation uses the self-exchange rate constants (k(AH/A) for AH + A) and the equilibrium constant to predict the rate constant for AH + B: k(AH/B) = (k(AH/A)k(BH/B)K(eq)f)(1/2). For a variety of transition metal oxidants, k(AH/B) is predicted within one or two orders of magnitude with only a few exceptions. For 36 organic reactions of oxyl radicals, k(AH/B) is predicted with an average deviation of a factor of 3.8, and within a factor of 5 for all but six of the reactions. These reactions involve both O-H or C-H bonds, occur in either water or organic solvents, and occur over a range of 10(28) in K(eq) and 10(13) in k(AH/B). The treatment of organic reactions includes the well-established kinetic solvent effect on HAT reactions. This is one of a number of secondary effects that the simple cross relation does not include, such as hydrogen tunneling and the involvement of precursor and successor complexes. This Account includes a number of case studies to illustrate these and various other issues. The success of the cross relation, despite its simplicity, shows that the Marcus approach based on free energies and intrinsic barriers captures much of the essential chemistry of HAT reactions. Among the insights derived from the analysis is that reactions correlate with free energies, not with bond enthalpies. Moreover, the radical character or spin state of an oxidant is not a primary determinant of HAT abstracting ability. The intrinsic barriers for HAT reactions can be understood, at least in part, as Marcus-type inner-sphere reorganization energies. The intrinsic barriers for diverse cross reactions are accurately obtained from the HAT self-exchange rate constants, a remarkable and unprecedented result for any type of chemical reaction other than electron transfer. The Marcus cross relation thus provides a valuable new framework for understanding and predicting HAT reactivity.     

Heteromeric assembled polypeptidic artificial hydrolases with a six-helical bundle scaffold

Enzyme efficiency results from the cooperation of functional groups in the catalytic site. In order to mimic a natural enzyme, a definite 3D scaffold must be carefully designed so that the functional groups can work cooperatively. During the HIV‐1 fusion process, the gp41 N‐ and C‐terminal heptad repeat regions form a coiled‐coil six‐helical bundle (6HB) that brings the viral and target cell membranes into close proximity for fusion. We used 6HB as the molecular model for a novel scaffold for the design of an artificial enzyme, in which the modified C34 and N36 peptides formed a unique 6HB structure through specific molecular recognition, and the position and orientation of the side‐chain groups on this scaffold were predictable. The histidine modified 6HB C34_H13/20/N36_H15/22 showed enzyme‐like hydrolytic activity towards p‐nitrophenyl acetate (PNPA; k_cat/K_M=3.66 M ^?1 s^?1) through the cooperation of several inter‐ or intrahelical imidazole groups. Since the catalytic activity of 6HB depends on the C‐ and N‐peptide assembly, either HIV fusion inhibitors that can compete with the formation of catalytic 6HB or denaturants that can destroy the ordered structure were able to modulate its activity. Further engineering of the solvent‐exposing face with Glu^?‐Lys⁺ salt bridges enhanced the helicity and the stability of 6HB. As a result, the population and stability of cooperative catalytic units increased. In addition, the Glu^?‐Lys⁺‐stabilized 6HB SC35_H13/20/N36_H15/22 had increased catalytic efficiency (k_cat/K_M=6.30 M ^?1 s^?1). A unique 6HB system was specifically assembled and provided a scaffold sufficiently stable to mimic the function of enzymes or other biomolecules.