Functional monomers and polymers. LXXXVI. Photochemical reactions on synthetic polymers with pendant thymine bases: Effect of solvents

Photodimerization of thymine bases present on the side chain of acryloyl and methacryloyl-type polymers was studied in dimethyl sulfoxide, dimethylformamide, and dimethyl sulfoxide—ethylene glycol mixture. Quantum efficiencies for photodimerization and quenching with isoprene were influenced by the solvents. The self-association of thymine bases estimated from their ultraviolet (UV) spectra and intrinsic viscosity were related to the effect of solvent on the photodimerization.     

高选择性透过二氧化硫气体分离膜的研究 （Ⅳ）不同烃基乙烯基亚砜接枝聚乙烯醇膜的透过性能

研究了不同烃基乙烯基亚砜接枝聚乙烯醇（ＰＶＡ－ＲＶＳＯ，Ｒ＝Ｍｅ，Ｅｔ，ｔ－Ｂｕ，Ｐｈ）膜对纯ＳＯ２、Ｎ２的透过性能以及ＳＯ２／Ｎ２混合气体的分离性能．结果表明上述膜对ＳＯ２具有高的选择性．对不同烃基乙烯基亚砜接枝膜进行了比较．     

Structural changes by sulfoxidation of phenothiazine drugs

Summary The side-chain conformations of psychoactive phenothiazine drugs in crystals are different from those of biologically inactive ring sulfoxide metabolites. This study examines the potential energies, molecular conformations and electrostatic potentials in chlorpromazine, levomepromazine (methotrimeprazine), their sulfoxide metabolites and methoxypromazine. The purpose of the study was to examine the significance of the different crystal conformations of active and inactive phenothiazine derivatives, and to determine why phenothiazine drugs lose most of their biological activity by sulfoxidation. Quantum mechanics and molecular mechanics calculations demonstrated that conformations with the side chain folded over the ring structure had lowest potential energy in vacuo, both in the drugs and in the sulfoxide metabolites. In the sulfoxides, side chain conformations corresponding to the crystal structure of chlorpromazine sulfoxide were characterized by stronger negative electrostatic potentials around the ring system than in the parent drugs. This may weaken the electrostatic interaction of sulfoxide metabolites with negatively charged domains in dopamine receptors, and cause the sulfoxides to be virtually inactive in dopamine receptor binding and related pharmacological tests.     

可溶性聚苯并噻吩的电化学合成

聚噻吩及其衍生物具有良好的导电性 ,优越的电致变色及荧光特性 ,可望用于研制各种新型微电子器件[1,2 ] .因此 ,这类聚合物的合成与表征一直受到广泛关注[3] .噻吩类聚合物是一个庞大的家族 ,其中聚异苯并噻吩早就被合成出来[4 ,5] .三氟化硼乙醚溶液 (ＢＦＥＥ)是电聚合芳香族化合物 (如噻吩、苯等 )的一种优良电解质[6～ 10 ] .在这一介质中 ,单体的氧化聚合电位很低 ,得到的导电高分子膜具有优良的机械力学性能 .本文将报道苯并噻吩在纯ＢＦＥＥ或ＢＦＥＥ与浓硫酸形成的混合电解质中的电化学聚合反应 .用这一方法合成得到了能发出蓝色…     

高选择性透过二氧化硫气体分离膜的研究 （Ⅳ）不同烃基乙烯基亚砜接枝聚乙烯醇膜的透过性能

研究了不同烃基乙烯基亚砜接技聚乙烯醇（ＰＶＡ－ＲＶＳＯ，Ｒ＝Ｍｅ，Ｅｔ，ｔ－Ｂｕ，Ｐｈ）膜对纯ＳＯ２、Ｎ２的透过性能以及ＳＯ２／Ｎ２混合气体的分离性能，结果表明上述膜对ＳＯ２具有高的选择性，对不同烃基乙烯基亚砜接枝膜进行了比较。     

等压法测定Li2SO4-MgSO4-H2O体系的渗透和活度系数

在25 ℃下, 离子强度范围分别为0.2—8.7、0.6—12.7和1.4—13.5 mol·kg~(-1)时, 测定了纯Li_2SO_4、MgSO_4及Li_2SO_4-MgSO_4混盐水溶液的渗透系数. 计算了Pitzer方程和Scatchard方程的离子作用参数. 用上述两种方程及由热力学关系式直接推导出的Mckay-Perring方程计算并比较了Li_2SO_4和MgSO_4在混合溶液中的平均活度系数, 三者在实验误差范围内一致. 利用获得的Pitzer参数计算该体系的溶解度与文献值基本一致.     

Theoretical Study of Small Water Clusters of Sulfur Dioxide

The intermolecular clusters of sulfur dioxide with water, SO2(H2O)n (n = 2～5), are studied by using B3LYP density functional theory and MP2 ab initio methods along with the large basis sets (6-311++G(d,p) and aug-cc-pVDZ). The equilibrium geometries, intermolecular binding energies, and anharmonic frequencies of the clusters are calculated and compared with those of pure water clusters and available experiments. SO2 tends to form cyclic hydrogen-bonded complexes with two or three water molecules. In the larger clusters, however, water molecules begin to retain the structure of pure water clusters and segregate from SO2. Infrared absorption assignments for the small clusters are discussed to resolve a possible incorrect assignment in a recent spectroscopic experiment on the clusters.     

银在浸出黄铜矿中的催化作用

本文研究了用Fe_2(SO_4)_3、MnO_2、FeCl_3、CuCl_2等浸出黄铜矿时Ag~ 的作用。Ag~ 在氯化物溶液中不起催化作用。但在酸性Fe_2(SO_4)_3及MnO_2溶液中可使反应速率常数提高200倍,文中导出了在Ag~ 催化作用下硫酸高铁浸出黄铜矿的动力学方程。确定了速率控制步骤是离子通过产物硫层的扩散过程,活化能为35.7kJ/mol。探讨了银催化浸出黄铜矿的反应机理。     

含偶氮苯与噻吩结构单元的共轭聚合物合成及酸致变色性质

以1,3-二(二苯膦基)丙烷二氯化镍(Ⅱ)作催化剂[Ni(dpp)Cl2],通过2,5-二溴噻吩格式试剂与4,4′-二碘偶氮苯共聚得到了一种新型共轭聚合物.采用红外光谱、核磁共振氢谱对聚合物的结构进行表征并通过紫外-可见吸收光谱、荧光光谱、X-射线衍射、热失重分析(TGA)、差热分析(DTA)等测试手段对聚合物的性能进行了详细的研究.紫外可见光谱分析结果表明,聚合物在384 nm处显示了偶氮苯发色团的特征吸收峰,相对于单体红移34 nm.在聚合物的氯仿溶液中观察到酸致变色现象,即分别加入CF3COOH和CH3SO3H后,溶液颜色由黄色分别变成墨绿色和紫色,而加入三乙胺溶液后溶液恢复到初始颜色.在25℃下测得的特性粘数为0.53 dL/g.热失重分析结果显示,该聚合物具有较好的热稳定性.     

Electrochemical,Chemical and Enzymatic Oxidations of Phenothiazines

The oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was performed in acetic acid with hydrogen peroxide or in formate buffers using persulfate. The enzymatic oxidation was performed in acetate or ammonium formate buffer by the enzyme horseradish peroxidase in the presence of H₂O₂. Molecules with, in the lateral chain, two carbon atoms (2C) separating the ring nitrogen and the terminal nitrogen, showed two parallel oxidation pathways, that is (i) formation of the corresponding sulfoxide and (ii) cleavage of the lateral chain with liberation of phenothiazine (PHZ) oxidized products (PHZ sulfoxide and PHZ quinone imine). Molecules with three carbon atoms (3C) separating the two nitrogens were oxidized to the corresponding sulfoxide. The chemical oxidation of all the studied molecules by hydrogen peroxide resulted in the corresponding sulfoxide with no break of the lateral chain. Oxidation by persulfate yielded, for the 3C derivatives, only the corresponding sulfoxide, but it produced cleavage of the lateral chain for the 2C derivatives. The origin of the distinct oxidation pattern between 2C and 3C molecules might be related to steric effects due to the lateral chain. The data are of interest in drug metabolism studies, especially for the early search. In the case of 2C phenothiazines, the results predict the possibility of an in vivo cleavage of the lateral chain with liberation of phenothiazine oxidized products which are known to produce several adverse side effects.     

Synthesis of Deuterium-Labeled Plant Sterols and Analysis of Their Side-Chain Mobility by Solid State Deuterium NMR

The plant sterols sitosterol and stigmasterol exert very different effects on plant model membranes, the first one being a "reinforcer" like cholesterol, the second one not. 25-(2)H-Stigmasterol has been synthesized by coupling of the 22-aldehyde derived from stigmasterol by ozonolysis, with the proper sulfone labeled in position 25. The configuration of the ethyl side chain at C-24 was controlled by separation of the diastereomers introduced via a chiral sulfoxide. This synthetic scheme allowed the introduction of a labeled side chain in plant sterols in eight steps for stigmasterol and nine for sitosterol (overall yield ca. 15%). Using both diastereomers, the 24-epimers of sitosterol (clionasterol) and stigmasterol (poriferasterol) have also been synthesized. Deuterium NMR on oriented lipid bilayers made of soybean phosphatidylcholine and containing these four labeled plant sterols clearly reveals the difference of orientation and mobility of the four side chains.     

丙炔醇聚合股对铁在酸性溶液中的缓蚀作用

应用电化学交流阻抗谱技术研究了Ｆｅ／Ｈ_２ＳＯ_４与Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中丙炔醇（ＰＡ）聚合膜的形成及其缓蚀作用,同时利用ＳＥＭ、ＡＦＭ及ＥＤＸ对ＰＡ聚合不同时期铁表面腐蚀形貌进行观测与成分分析．结果表明,Ｆｅ／Ｈ_２ＳＯ_４与 Ｆｅ／Ｈ_２ＳＯ_４＋ Ｈ_２Ｓ体系中 ＰＡ可逐渐聚合成膜,从而有效抑制基体的腐蚀,使电极表面较为平整,微米尺度下呈现规则的块状结构;但Ｆｅ／Ｈ_２ＳＯ_４体系中宏观上ＰＡ并未形成连续的保护膜,导致电极表面局部发生腐蚀;而Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中,Ｈ_２Ｓ、ＨＳ－在电极表面的吸附减缓了ＰＡ聚合成膜,但长时间腐蚀后,由于硫化物的生成覆盖在ＰＡ聚合膜上,使其具有长期缓蚀效能．     

Influence of Grafted Chain Length of a Phenolic Copolymer on Its Complex Formation with Poly(vinyl Pyrrolidone) and Poly(ethylene Oxide)

A phenolic copolymer has been grafted with oligomers of different chain lengths. Polymer-polymer complexation has been studied between graft copolymers and nonionic polymers, such as polyvinyl pyrrolidone) and poly(ethylene oxide), in an acetone-methanol mixture by several methods, e.g., viscosity, conductance, and apparent pH measurements. A distinct stepwise complexation between PVP and graft copolymers has been observed. The length of the side chain also seemed to influence interpolymer complex formation. Some of these observations have been interpreted with reference to the actual structure of the graft copolymers.     

硫酸铈中铈的价态及其温度依赖性的XPS研究

近年来人们对混合价化合物的研究十分关注,已发现的这类化合物主要是稀土元素的金属化合物。最近笔者在研究稀土化合物的电子能谱时观察到,固态硫酸铈(Ⅳ)也是一种混合价化合物(或称波动价化合物),而且铈的价态与温度有关,还发现硫酸缔的热分解行径与文献报道有很大出入。     

Barton radical reactions of 2-C-branched carbohydrates

Barton esters have been introduced into the side chain of carbohydrates with high yields in only a few steps from easily available glycals. Their radical reactions afford 2-C-methyl and 2-C-bromomethyl hexoses, pentoses and disaccharides in good yields in analytically pure form. Since the Barton esters have been synthesized by an oxidative radical addition and their transformations by reductive radical processes, our results demonstrate the power of such reactions in carbohydrate chemistry.     

Effect of temperature on the surface phase behavior and micelle formation of a mixed system of nonionic/anionic surfactants

The adsorption and micellar behavior of diethylene glycol mono-n-tetradecyl ether (C14E2), sodium 3,6,9,12-tetraoxaoctacosanoate (TOOCNa), and their mixture at a 1:1 molar ratio have been studied by film balance, Brewster angle microscopy (BAM), and surface tensiometry at different temperatures. The monolayers of pure C14E2 and its mixture with TOOCNa show a first-order phase transition with a conspicuous cusp point in their respective adsorption isotherms. This is further confirmed by the observation of bright two-dimensional condensed phase domains visualized by BAM just after the appearance of the phase transition. It is interesting to note here that for C14E2, condensed domains are observed up to 19 degrees C, while in the mixed system, they are observed up to 22 degrees C. To understand why in the mixed system the domains are observed at higher temperatures than for pure C14E2, we have measured the temperature dependency of the equilibrium surface tension at > or = cmc (gammacmc) values of both the pure and the mixed systems. The gammacmc values of pure C14E2 remain almost constant, while those of pure TOOCNa and its mixture with C14E2 decrease appreciably with increasing temperature. It is concluded that higher degree of dehydration of the ethylene oxide (EO) chain reduces the head-group size of TOOCNa, which outweighs the combined effect of the repulsive interactions between the head-groups and the thermal motion of the adsorbed molecules. Furthermore, C14E2 being inserted into the TOOCNa monolayer reduces the electrostatic repulsions between the charged heads, and consequently, the adsorbed monolayers attain closer molecular packing. As a result, the gammacmc values of both pure TOOCNa and its mixture with C14E2 decrease with increasing temperature. This facilitates the formation of condensed domains in the mixed system at higher temperatures, whereas none of the individual members can show any indicative feature of phase transition under the same experimental conditions.     

正丁烷、正丁烯-1、丁二烯-1, 3在极性非质子溶剂和质子溶砒中的溶剂化

本文的目的是研究碳四气体在极性非质子溶剂和质子溶剂中的溶剂化规律。对碳四气体的选择主要考虑不同键型的代表性, 溶剂以极性非质予溶剂为主。本文用量热法测定了298.15 K、1 atm下正丁烷、正丁烯-1、丁二烯-1,3在二甲基甲酰胺、二甲基亚矾、碳酸丙烯酯、N-甲基吡喀烷酮和甲醇中的摩尔溶解热。依据测定值对碳四气体的溶剂化规律进行了讨论。用溶度参数法对溶剂化焓进行了理论计算, 在极性非质子溶剂中得到较好的结果, 质子溶剂的有效溶度参数则表现出局限性。Pierotti理论如不加修正则不能较好地适用于本文体系。     

热处理对聚噻吩结构性质的影响

用WAXS、FTIR、TGA方法研究了在氮气和空气中热处理聚噻吩(PT)某些结构性质.氯仿不溶分子量较高样品(PT_2)热稳定性高于氯仿可溶低分子量样品(PT_1).PT_2在氮气中380℃热处理30分钟,结晶度和相干长度都明显增加,可获得多于11个结晶衍射线.PT_1只能在较低温度下热处理,晶性无明显改善.结晶度低分子量大的样品,有利于掺杂进行.掺杂后得到较高的导电率.给出了热处理及掺杂前后的FTIR谱的解释与归属,热处理后688、831-833cm~(-1)明显减弱;经掺杂后出现了五个新吸收带:1016-1024、1105-1110、1196-1201、1323和1632cm~(-1).     

Fabrication of mesoporous polymer monolith: a template-free approach

Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.     

Asymmetric synthesis of rubiginones A(2) and C(2) and their 11-methoxy regioisomers

Convergent enantioselective syntheses of angucyclinone-type natural products rubiginones A(2) (2) and C(2) (1) and their 11-methoxy regioisomers 3 a and 3 b have been achieved by using two domino processes from a common enantiomerically pure 1-vinylcyclohexene 4. Key steps in the synthesis of this diene were the stereoselective conjugate addition of AlMe(3) on (SS)-[(p-tolylsulfinyl)methyl]-p-quinol (9) and the elimination of the beta-hydroxy sulfoxide fragment, after oxidation to sulfone, to recover a carbonyl group. The first domino sequence comprised Diels-Alder reaction with a sulfinyl naphthoquinone followed by sulfoxide elimination. An efficient opposite regioselection in the cycloaddition step was achieved in the convergent construction of the tetracyclic skeleton using a sulfoxide at C-2 or C-3 of the dienophiles 5 or 6, derived from 5-methoxy-1,4-naphthoquinone. The second domino process, triggered by oxygen and sunlight, allowed the transformation of the initial tetracyclic adducts into the final products after B ring aromatization, silyl deprotection and C-1 oxidation.