9,10—二氰基蒽光敏分解水制氢反应的研究

本文以9、10-二氰基蒽(DCA)为敏化剂,测定了用胺类,单烯类及取代苯类化合物为电子给体时光敏还原甲基紫精(MV~(2+))的量子产率。用三乙醇胺(TEOA)为电子给体,探索了胶体铂存在下DCA光敏分解水制氩的反应条件并研究了用甲苯、对二甲苯为电子给体时DCA光解水制氢的反应。结果表明以DCA为敏化剂时许多化合物(E~(ox)<2V)均可作为电子给体,在制氢的同时还有可能合成有用化合物等优点。     

香豆素酮类化合物的瞬态研究——Ⅲ.香豆素酮和碘鎓盐间的电子转移

本工作采用激光闪光光解法对香豆素酮类化合物敏化碘鎓盐化合物问题进行了研究。结果表明:碘鎓盐化合物能通过电子转移机理猝灭香豆素酮的激发三重态。工作中还用甲基紫精(PQ~(2+))为模型化物,观察到它也能使香豆素酮的三重态猝灭,同时可看到在位于610nm处的PQ~+生成。这些结果说明,在发生电子转移的反应中香豆素酮是电子给体,按Weller公式的计算结果也表明它们之间可发生电子转移反应。     

光诱导α-氨基酸的脱羧加成反应

文章主要研究以α-氨基酸和缺电子烯烃作为反应底物的Michael加成反应,以乙腈作溶剂,菲(phen)、1,4-二氰基萘(DCN),1,4-二氰基苯作光敏剂,在紫外光的照射下通过单电子转移过程,与缺电子烯烃发生加成反应,形成一系列脱羧加成产物。该类反应条件温和,产物的产率达65%。     

9,10-二氰基蒽敏化光氧化反应的溶剂效应

本文通过α-,β-蒎烯及1,4-二苯基-1,3-丁二烯的9,10-二氰基蒽(DCA)敏化光氧化反应在一系列溶剂中产物生成的相对量子效率及单线态氧(~1O_2)产物的含量,对β-蒎烯在乙腈中的反应动力学分析,讨论了反应的溶剂效应,证明了DCA敏化光氧化反应,包括~1O_2产物都是经由电子转移的反应机理。     

以9,10-二氰基蒽为敏化剂对几种硫醚光氧化初级反应机理的研究

本文研究了多种硫醚化合物对9,10-二氰基蒽(DCA)的荧光猝灭过程,并观察到DCA与硫醚间形成的激基复合物的荧光发射峰。这些证据表明,受光激发后DCA与硫醚之间发生了电子转移。以DCA作敏化剂可氧化异丁基硫醚、羟乙基硫醚以及难以被单线态氧氧化的苯基硫醚。其反应机理可能经历了电子转移,生成氧负离子(superoxide),然后再氧化硫醚生成亚砜这样的过程。     

含香豆素基团树形聚丁二烯的合成

通过Cu(I)催化下的叠氮基团和端炔的环加成反应(Cu AAC),将炔基修饰的香豆素小分子连接到含有叠氮基团的树形聚丁二烯模板上,形成具有"半封闭"式结构的含香豆素基团的线型/星型梳状聚丁二烯。反应产物采用1H-NMR、FT-IR进行表征。     

8-甲氧基呋喃并[3’,2’:6,7]香豆素与烯烃的光环合加成反应——Ⅱ.8-MOP与环己烯、二氢吡喃的反应

我们曾研究了8-甲氧基呋喃并[3′,2′∶6,7]香豆素(8-MOP)与环己烯的光环合加成反应。本文进一步研究了8-MOP与2,3-二氢-γ-吡喃的光环合加成反应,并将上述两个反应的产物分离、鉴定,研究了其立体化学。     

反,反—1,4—二苯基—1,3—丁二烯电子转移光氧化反应中的盐效应

本文研究了在二氟甲烷中9,10-二氢基蒽(DCA)敏化光氧化反,反-1,4-二苯基-1,3-丁二烯(DPB)反应中四氟硼酸四正丁基铵盐的作用,认为四极铵盐能促进激基复合物的解离,增加电荷分离,加速反应的进行并影响产物的分布。本文还讨论了盐效应对电子转移光化学反应中机理研究的作用及在合成应用中的可能性。     

氰基蒽的电子转移荧光猝灭及激基复合物

本文测定了在不同溶剂中一系列化合物以及氧分子对9,10-二氰基蒽(DCA)及9-氰基蒽(CNA)的荧光淬灭常数k_q值及DCA与2,5-二甲基呋喃的激基复合物的发射光谱。这些化合物的k_q值与计算所得自由能的变化△G之间的关系基本符合Rehm-Wdler关系。溶剂极性及溶剂粘度对荧光猝灭反应有影响,影响强电子给体k_q值的主要因素是溶剂的粘度,而弱电子给体的k_q值则主要决定于溶剂的极性。氧分子的k_q值基本上与溶剂扩散速率常数走k_(diff)值吻合。     

光化学反应中的磁场效应 Ⅱ.电子转移光敏化1,2-二苯乙烯的顺反异构化反应

前文报道了外加磁场对吸附在硅胶表面上的芳砜光解反应的影响,本文报道外加磁场影响光化学反应的另一个例子——电子转移光敏化1,2-二苯乙烯的异构化。 近年来电子转移光敏化反应引起了有机光化学家们的极大注意。一些异构化、重排、裂解、氧化反应都可以通过电子转移机理敏化。电子转移光敏化的机理可以用(1)描述。图中A和D分别代表电子的受体和给体。     

Photoaddition of fluoroolefins on aromatic polyamide

A photografting method has been developed to surface treat aromatic polyamide fabrics in the presence of fluoroolefin vapors. The new fabrics are more flame resistant in oxygen-enriched environment than untreated commercial aramid fabrics. The photoaddition reaction of haloolefins has been shown to irreversibly modify the fabrics, which were analyzed by water wettability, scanning electron microscopy, x-ray analysis, and ¹⁹F nuclear magnetic resonance spectroscopy.     

Unusual addition by the thiol-ene photopolymerization

Summary The photoaddition of aromatic dithiols (1) onto aliphatic alkenes (2a-2c) yielding polysulfides is studied. Polysulfides having anti-Markownikow and Markownikow moieties in the main chain are obtained by the reaction of dithiols (1) with ethyleneglycoldivinylether (2a). The unusual Markownikow orientation is explained on the basis of a radical cation intermediate.     

Photoaddition of Acetylcyclohexane and Ethanol

1-Acetylcyclohexene undergoes photoaddition with ethanol to give, initially, cis- and trans-2-ethoxy-1-acetylcyclohexane. The thermodynamically less stable cis isomer is the major product. No products resulting from photochemical hydrogen atom abstraction from ethanol by photoexcited ketone were observed in contrast to the results obtained with an acetylcyclopentene derivative. The initially formed adducts undergo a further photochemical reaction, intramolecular hydrogen atom abstraction, to give derivatives of octahydrobenzofuran. Quantum yields for disappearance of acetylcyclohexene in ethanol were 0.04 at 2537Å and 0.25 at 3130Å.     

Surface-active properties and thermal behavior of S-alkylthio-carboxylic acids and their potassium salts

S-Alkylthiocarboxylic acids and their potassium salts were prepared by photoaddition of α-olefins (C₁₀, C₁₂, and C₁₄) with mercapto carboxylic acids such as thiomalic acid, thiopropionic acid, and thioglycolic acid. The physicochemical solution properties and thermal stabilities for three series of thiosurfactants were evaluated. S-Alkylthiocarboxylic acids that contain bridged S-bonds provide excellent thermally stable surfactants, and their alkaline salts exhibit good surface activity.     

Hybrid networks derived from isosorbide by means of thiol-ene photoaddition and sol–gel chemistry

New bridged silsesquioxanes derived from isosorbide were synthesized, according to the sol–gel process, by acidic or basic hydrolysis and condensation of a bis-trimethoxysilyl precursor. The latter was prepared by thiol-ene photoaddition of 3-(trimethoxysilyl)-1-propane thiol on diallyl isosorbide ether synthesized by a phase-transfer-catalyzed reaction of allyl bromide with isosorbide. The structure of those hybrid networks prepared according to a sol–gel process was investigated by ²⁹Si solid-state NMR and X-ray diffraction experiments. Acid hydrolysis leads to the formation of randomly branched structures while basic catalysis promotes the creation of clusters. The anisotropic character of the hybrid networks was evidenced by cross polarized optical light observations (birefringence), demonstrating an organization at the micrometric-scale. These hybrid networks derived from isosorbide showed a thermal stability up to 360 °C.     

Hybrid Porous Microparticles Based on a Single Organosilica Cyclophosphazene Precursor

Porous organosilica microparticles consisting of silane-derived cyclophosphazene bridges were synthesized by a surfactant-mediated sol-gel process. Starting from the substitution of hexachlorocyclotriphosphazene with allylamine, two different precursors were obtained by anchoring three or six alkoxysilane units, via a thiol-ene photoaddition reaction. In both cases, spherical, microparticles (size average of ca. 1000 nm) with large pores were obtained, confirmed by both, scanning and transmission electron microscopy. Particles synthesized using the partially functionalized precursor containing free vinyl groups were further functionalized with a thiol-containing molecule. While most other reported mesoporous organosilica particles are essentially hybrids with tetraethyl orthosilicate (TEOS), a unique feature of these particles is that structural control is achieved by exclusively using organosilane precursors. This allows an increase in the proportion of the co-components and could springboard these novel phosphorus-containing organosilica microparticles for different areas of technology.     

Hydrophilic monolith with ethylene glycol-based grafts prepared via surface confined thiol-ene click photoaddition

Macroporous polymeric monolith bearing thiol-reactive surface functionalities was prepared within micrometer-sized fused silica capillary column by photochemically-driven free radical copolymerization of N-acryloxysuccininimide and ethylene dimethacrylate in the presence of toluene as porogenic solvent, hereafter poly(NAS-co-EDMA), and subsequent surface grafting of allylamine through nucleophilic substitution reaction. The pore surface with pendant allyl moieties was further functionalized via a two-step thiol-ene click reaction with thiol-containing oligo(ethylene glycol) and mercaptoethanol, successively. The surface hydration ability, i.e. hydrophilic character, of the as-obtained monolith was evaluated as a function of the water-content of the liquid fluid environment through electrochromatographic evaluation of the retention properties of the -(O-CH₂-CH₂)-like surface-functionalized capillary monolith. A major result was that the so called hydrophilic interaction electrochromatographic mode was observed at a given mobile phase composition. An example is given for the separation of phenol-derivatives, with the most hydrophilic one being the most retained. In addition, the hydrophilic interaction based separation allowed for reduced analysis time as compared to the separation observed under reversed-phase separation mode using analogous monolithic stationary phase. Finally, the versatility of the thiol-ene photoaddition approach is demonstrated with an example of C18-like monolith for reversed-phase separation application.     

Novel second generation dendrimer with terminal thiol groups and its thiol–ene photopolymerization with unsaturated monomers

A facile and effective method to prepare a second generation dendrimer (G2SH) and the use of this molecule as monomer for thiol–ene photopolymerizations, are described. The first step involves the “Click” thiol–ene photoaddition of 3-allyloxy-1,2-propanediol onto pentaerythritol tetrakis mercaptopropionate, producing an intermediate octaol. In the second step, this intermediate is esterified with 3-mercaptopropionic acid, achieving a first generation dendrimer with eight thiol groups (G1SH), and finally, the same sequence of reactions is then performed with this compound to produce the second generation dendrimer with 16 groups (G2SH). This dendrimer was used as a monomer for thiol–ene photopolymerizations in conjunction with 1,6-hexanedioldiacrylate (HDDA), pentaerytritol triacrylate (TAC) and triallyl triazine (CN). The kinetics of photopolymerization were determined by RT-FTIR and optical pyrometry, finding the following order of reactivity: HDDA > TAC > CN. Homopolymerization and step-growth polymerization occurred simultaneously in the cases of the acrylates while the CN reacted almost exclusively with G2SH. The reactivity of G2SH was compared with that of precursors G1SH and PETKMP. The results showed that G2SH was slightly more reactive than the other two thiols. The viscoelastic properties of the obtained flexible materials were determined by DMA which showed that the polymers displayed decreasing Tg's with increasing size of the thiol.     

头孢曲松钠结晶工艺研究

为了改善头孢曲松钠的流动性和比容,优化头孢曲松钠的结晶工艺。将头孢曲松钠粗品加入注射用水中溶解,再加一定量的丙酮稀释,并控制水浴温度为10～15℃,加入适量的活性炭脱色30 min,过滤,用丙酮水混合液洗涤炭饼,溶解液再经0.22μm膜滤后移入四口烧瓶中,加入适量晶种,滴加丙酮结晶,完成后过滤、洗涤、干燥。通过考察头孢曲松钠结晶工艺中的晶种加量、搅拌速度、流加速度和结晶温度4个因素对产品比容及流动性的影响,得出结论:当晶种加量0.3%、搅拌速度为170 r/min、流加速度为2 mL/min、结晶温度为10～15℃时,得到的产品比容小,流动性好。     

羟丙基壳聚糖微球的制备与性能

以壳聚糖、环氧丙烷为原料合成羟丙基壳聚糖,以此为壳材,以胰岛素为芯材,制备微球,并考察微球的性能.单凝聚法制备微球.通过IR、XRD和DSC表征微球的化学结构,采用光学显微镜和扫描电镜观察微球的形貌,并考察微球稳定性.搅拌速度为400 r/min、交联荆用量为0.15 mL、HPCS浓度为8%,得到的微球形状规整,包埋率为63%,粒径大小适中,分布范围窄;各种环境下稳定性合适.羟丙基壳聚糖包覆胰岛素微球各种性能研究表明:此载药微球满足药用需要.