温度/氧化还原双响应超分子胶束的制备及释药性能研究

以溴酰化β-环糊精(β-CD-Br)为引发剂,通过原子转移自由基聚合(ATRP)制备了以β-CD为核的温敏星形聚N-异丙基丙烯酰胺(β-CD-PNIPAM)。以具有氧化还原性质的二茂铁-聚乙二醇(Fc-m PEG)为客体分子,通过环糊精和二茂铁的主-客体识别作用自组装得到温度/氧化还原双响应超分子复合胶束(β-CD-PNIPAM/Fc-mPEG)。结果表明,超分子复合胶束具有规则的球形结构,直径约为100nm左右,具有可逆的温度和氧化还原刺激响应性。当升高温度至胶束的LCST以上且加入不同浓度的H2O2时,胶束结构破坏,实现药物的可控释放。这种具有良好温度和氧化还原双响应特性的超分子胶束是抗癌药物的良好载体。     

兼具有强阴离子性与疏水缔合性的丙烯酰胺三元共聚物

在微乳液介质中实施了丙烯酰胺 (AM)、苯乙烯 (St)、2 丙烯酰胺基 2 甲基丙磺酸钠 (NaAMPS)的共聚合 ,制备了既含有强阴离子性基团 (—SO3Na)又含有疏水基团 (St)的丙烯酰胺三元共聚物AM NaAMPS St;通过红外光谱法、紫外分光光度法及元素分析法对共聚物的结构及组成进行了表征 ;稀释外推粘度法测定了共聚物的特性粘数 ;测定了共聚物纯水溶液及盐水溶液的表观粘度 ;荧光探针法考察了三元共聚物的疏水缔合性以及离子基团对疏水缔合性的影响规律 .实验结果表明 ,在聚丙烯酰胺 (PAM )分子主链上同时引入强阴离子性基团与疏水基团后 ,阴离子的电粘效应与疏水基团的疏水缔合作用相互协同 ,会使共聚物水溶液的黏度显著提高 ;盐溶液对疏水缔合作用的增强效应与强阴离子基团对盐的较大容忍度相互结合 ,会使共聚物水溶液的抗盐性能明显得以提高 ;大分子链上的强阴离子基团磺酸根的存在 ,在一定程度上会削弱疏水基团之间的疏水缔合作用 ,即对疏水基团的疏水缔合行为会产生一定的负性影响 .     

丙烯酰胺-苯乙烯双亲嵌段共聚物水溶液的粘度性能

通过改变丙烯酰胺 (AM)与苯乙烯 (St)两单体的投料比 ,在微乳液介质中制备了分子组成系列变化的丙烯酰胺 苯乙烯双亲嵌段共聚物 (PAM b PSt) ,使用旋转粘度计测定了共聚物水溶液的表观粘度 ,详细考察了共聚物浓度、共聚物链结构、剪切速率、盐度及温度等因素对共聚物水溶液表观粘度的影响规律 .研究结果表明 ,由于PAM b PSt分子链中的PSt疏水嵌段链段之间具有强的疏水缔合作用 ,导致其具有独特的流变性能 .当共聚物水溶液的浓度高于某一临界值后 ,疏水缔合作用以分子间的缔合为主 ,大分子链之间会形成动态物理交联网络 ,增大了流体力学体积 ,使PAM b PSt水溶液可产生良好的增稠性能 ;疏水缔合作用是一吸热过程 ,升高温度有利于分子间的缔合 ,因此PAM b PSt水溶液具有良好的耐温性 ;聚合物水溶液中盐类物质的存在 ,会增强溶剂的极性 ,有利于分子间的缔合 ,使PAM b PSt水溶液具有良好的耐盐性 .     

丙烯酰胺-苯乙烯双亲嵌段共聚物水溶液的表面活性及增溶性

在微乳液介质中制备了系列的丙烯酰胺 (AM)与苯乙烯 (St)的双亲嵌段共聚物 (PAM b PSt) ,用紫外分光光度法测定了共聚物的组成 ,用乌氏粘度计测定了共聚物的特性粘数 [η],并用其相对表征共聚物的分子量大小 .重点研究了双亲嵌段共聚物 (PAM b PSt)疏水链段在水溶液中的缔合行为、共聚物的表面活性及其对有机物的增溶性能 ,考察了共聚物分子组成 (疏水链段含量 )与分子量对其表面活性与增溶性能的影响规律 .研究结果表明 ,由于疏水链段的憎水性 ,PAM b PSt的分子链在水溶液表面会形成表面吸附 ,从而降低水溶液的表面张力 ;而在水溶液中 ,在疏水相互作用下 ,PAM b PSt分子链中的苯乙烯疏水链段会形成分子间或分子内的胶束 ,烃类有机物可增溶其中 ;疏水链段含量越大 ,分子量越小 ,PAM b PSt的表面活性与增溶性能越强     

Janus超支化超分子聚合物的构筑及电化学响应性自组装行为研究

本工作报道了第一例具有电化学氧化还原刺激响应性的Janus超支化超分子聚合物,研究了其自组装及响应性解组装的行为.通过阴离子开环聚合和阳离子开环聚合的方法,分别合成了以β-环糊精为中心的亲水超支化聚缩水甘油醚CD-g-HPG和末端为二茂铁的疏水超支化聚（3-乙基-3-羟甲基环氧丁烷）Fc-g-HBPO.两者通过Fc/CD之间的主客体包结络合作用,构筑了两亲性Janus超支化超分子聚合物HBPO-b-HPG.该聚合物在水中可以自组装形成囊泡.通过动态光散射（DLS）跟踪、2D-NOESY和循环伏安曲线表征了CD-g-HPG和Fc-g-HBPO之间的主客体包结络合作用,通过扫描电子显微镜（SEM）和透射电子显微镜（TEM）表征了囊泡结构.最后,研究了囊泡在电化学刺激下的解组装行为,同时也验证了囊泡在加热、加入主客体竞争分子和化学氧化下的稳定性.     

水溶性显色型分子识别器-甲基红基乙二胺基羟丙基-β-环糊精

通过选择性氧化,将水溶性优良的羟丙基-β-环糊精转化为丙酮基羟丙基-β- 环糊精。再利用乙二胺分子作为柔性链和连接剂键连制得水溶性的甲基乙二胺基羟 丙基-β-环糊精。在甲基红基乙二胺基羟丙基-β-环糊精的稀水溶液中（6 * 10~ (-8) ～ 2 * 10~(-5) mol·dm~(-3))加入已烷等疏水性客体分子时,甲基红基团 可被掎到β-环糊精空腔外。若是在酸性介质中,甲基红基团还会同时发生偶氮基 团的质子化反应,并伴随颜色的变化（由黄色→红色）,该变色程度与客体分子的 外型、体积及极性等有关,从而起到分子检测器的作用。     

氧化还原响应性长链超分子超支化聚合物的构筑及药物控释研究

首先合成了一种同时含有端巯基、端炔基且具有β-环糊精(β-CD)/二茂铁(Fc)超分子主客体作用的AB2型长链大分子单体(MM),再利用其巯基和炔基的点击反应可以合成出氧化还原响应性长链超分子超支化聚合物(SHP).利用一维和二维核磁共振谱对MM和SHP的聚合物结构和超分子作用进行了表征和确认.动态光散射和透射电子显微镜测试结果表明:在水溶液中,SHP可自发地形成支化自组装形貌;而当加入H_2O_2后,由于β-CD/Fc主客体作用的解离,支化自组装体结构被破坏、且进一步二次组装球形胶束.对比于线型超分子聚合物自组装体,SHP具有更高的载药效率.利用紫外分光光度计测试载药SHP自组装体对抗癌药物阿霉素(DOX)的累积释放曲线发现H_2O_2可有效调控SHP自组装体中DOX的释放速率,即:当加入H_2O_2后,DOX的释放速率明显加快.     

硫醇分子链长对氧化还原自组装多层膜电化学行为影响的初步研究(英文)

以烷基硫醇和二茂铁衍生物构建的氧化-还原自组装多层膜为模型体系,研究烷基硫醇分子链长对多层膜电化学行为的影响.实验表明,二茂铁基团和电极之间的电子传递反应速率随两者距离的增加呈现指数级下降的趋势;烷基硫醇分子链长对自组装膜电化学行为的影响于不同情况下表现不同.本实验条件下,当多层膜上的电活性基团与电极比较接近时,长链分子自组装膜呈现较强的电化学响应.而当电极与电活性基团之间的距离较远时,短链烷基硫醇分子自组装膜呈现较强的电化学响应.     

聚丙烯酰胺类疏水缔合物的增黏因素研究

合成了6种不同修饰度的聚丙烯酰胺疏水聚合物(PAM1~PAM6), 考察了聚合度、 共聚物片段含量及疏水基团大小等内部因素和聚合物的抗剪切能力、 剪切恢复性及抗盐性等外部因素对这些疏水聚合物分子间、 分子内缔合的影响规律.     

二茂铁表面活性剂的电化学行为

以循环伏安法为主要手段,研究了具有可逆特性的二茂铁表面活性剂(N,N-二甲基二茂铁甲基十四烷基溴化铵,Fc14)在0.1 mol/L Na2SO4溶液中形成胶束对电化学行为的影响,并讨论了pH、扫描速度及浓度对Fc14电化学行为的影响.结果表明,Fc14在pH=2左右具有良好的可逆变化特性,在氧化态(I2+)与还原态(I+)之间可实现自由转换;Fc14在玻碳电极上的logIpc~logv呈现良好的线性关系(R20.991).当Fc14的浓度大于2 mmol/L时,电化学氧化过程以扩散控制为基本特征;当浓度小于0.2 mmol/L时,电极吸附现象的特征趋于明显.与此同时,Ipc和扩散系数(D)在Fc14的临界胶束浓度(CMC)附近出现突变,这与Fc14表面张力变化趋势相吻合.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.