Ⅰ.基于包结络合作用的光控可逆自组装 Ⅱ.微波促进下芳基卤代物与亚磺酸钠反应研究

【作者】 邹炯；

【导师】 陶凤岗； 江明；

【作者基本信息】 复旦大学 ， 有机化学， 2008， 博士

【摘要】 超分子化学是以分子为构筑单元,以分子间非共价键为基础,以分子形成的有序聚集体为研究对象的“分子以上层次”的化学。超分子化学中的核心问题是分子自组装,这是指构筑基元借助于分子间力自发地形成有序结构。构筑基元可以是无机分子,有机小分子,高分子,以及生物大分子等。在分子自组装的多种驱动力中,主一客体包结络合作用占有重要的地位,环糊精(Cyclodextrin)是第二代主体化合物的代表,其空腔可以包结多种分子,它已被深入研究。近年来我们课题组建立了一种构建聚合物胶束的非嵌段共聚物路线,由此可采用均聚物对作为组装单元,这样连接聚集体胶束的壳和核层的作用力是氢键而不是化学键,这种方法形成的就是“非共价键接胶束”(NCCM)。用来构筑NCCM的驱动力通常为氢键、疏水相互作用或范德华力等等,本论文在此基础上开展,将环糊精-偶氮苯的包结络合作用引入到我组大分子自组装的研究中,论文可分为以下几个方面:第一部分:我们通过合理的设计,通过四步反应,合成了带有偶氮苯基的一系列疏水小分子。在选择性溶剂中通过在特定温度下将疏水小分子缓慢注入在α-、β-环糊精的水溶液,我们成功实现了胶束化。通过动态光散射,透射电镜,扫描电镜等表征,我们发现该胶束具有薄壁空心球形态,大小约为200nm。我们接着用一定强度的紫外光对囊泡进行了照射,而胶束并没有消失,在用电镜观察胶束的形态时我们发现空心结构消失,同时观察到产生许多实心的无规聚集体。在光散射实验中,我们发现胶束尺寸和大小分布发生的明显变化。通过对机理的研究,我们认为是由于偶氮分子由反式转变为顺式后从环糊精的空腔中脱离,从而破坏了两亲性小分子组装体,导致了胶束的解离,形成无规聚集。而后,我们用可见光对胶束进行照射,紫外一可见光谱表明:偶氮分子由顺式变为反式。通过动态光散射测试,我们发现胶束的尺寸和分布均发生了可逆的变化。接着,我们把样品制备在铜网上用透射电镜观察了胶束,发现胶束薄壁呈囊泡结构,壁厚约为10nm符合双层膜模型。从而我们认为可见光使偶氮分子由顺式变为反式后,偶氮重新进入环糊精空穴组成双亲性分子,在水中原位组装形成了囊泡。我们成功实现了基于非共价作用光控可逆的囊泡—无规聚集的转化。第二部分内容是对前面工作的扩展。我们设计合成枝状分子扇片为组装单元,修饰上偶氮基团后形成疏水部分。共合成了一代至三代三种偶氮苯基枝状分子:G1-Azo、G2-Azo、G3-Azo。接着通过对β-环糊精的修饰,在主面上引入单取代的对甲苯磺基后,乙二胺胺解得到EDA-CD,与2-异丙酰氯反应得到环糊精的ATRP引发剂,与单体NIPAM发生ATRP聚合合成了端基为β-环糊精的PNIPAM,作为亲水部分。在THF中能溶解G1-Azo和端基为β-环糊精的PNIPAM。将一定浓度的混合液注入水中发现形成胶束。通过动态光散射的研究,我们发现胶束的粒径大约在150～200nm,颗粒大小以及分散度随着溶液浓度的增大呈有规律的变化。此外我们通过原子力显微镜(AFM)和透射电镜等表征方法确定颗粒呈薄壁囊泡结构。我们认为是偶氮小分子进入了环糊精的空腔,而端基为β-环糊精的PNIPAM是亲水性的,因此形成非共价作用的双亲性分子。然而Dendron的扇片分子之间的相互作用能够在水中发生自组装形成薄壁双分子囊泡结构,界面由PNIPAM的作用而稳定。接着我们分别用紫外和可见光照射胶束,实现了胶束结构由囊泡到实心球的转变。在此工作中我们成功实现了基于非共价作用的嵌段聚合物的合成,并通过光照射实现了光控可逆的囊泡—无规聚集的转化。在第三部分工作中我主要介绍基于包结络合作用的光控可逆枝状分子的合成研究。近年来,具有规则构型的树枝状分子的研究逐渐成为有机化学、高分子化学以及材料化学等领域的热点。而目前还没有文献报道通过超分子包结络合作用行成的具有规则构型的树枝状分子。通过有机反合成分析,我们设计了两种单体(A,B)。单体A是由一分子偶氮苯和两分子的β-环糊精构成;单体B是由一分子金刚烷和两分子α-环糊精构成。在水溶液中β-环糊精和金刚烷能形成稳定包结络合物,α-环糊精更易于和偶氮苯进行包结络合。因此形成ABAB交替的基于包结络合的枝状分子。在紫外光照射下由于偶氮的顺反异构变化可以使枝状分子解离,形成光控可逆的基于包结络合作用的枝状分子。合成过程比较复杂,还有部分尚未完成。第四部分工作主要是微波促进的二芳基砜以及芳基烷基砜的合成方法研究。我们发现在微波辐照下,带有强吸电子基团的卤代烷烃能与亲核试剂甲亚磺酸钠,苯亚磺酸钠发生S_NAR型亲核取代反应,生成芳基烷基砜和二芳基砜。通过反应条件筛选我们得到了优化的反应条件,拓展底物合成了17种砜类化合物。和以往的合成方法相比,微波促进的反应大大降低了反应时间(由16小时降为10分钟),产率也有所提高。在对甲亚磺酸钠与邻氟苯腈的反应中我们发现了新的关环反应,并提出了其可能的反应机理。更多还原

【Abstract】 Supramolecular chemistry is based on the non-covalent interaction between moleculars.Molecular self-assembly,which is the most important area in suprachemistry, means spontaneous building-up of complex structures via intermolecular interaction, from various building blocks including inorganic and organic molecules and macromolecules.Etc.The host-guest inclusion plays an important role among all kinds of driving forces leading to self-assembly.Cyclodextrins(CD) is one of the most important host molecules in supramolecular chemistry and have been fully researched.In recent years,our group has developed "block-copolymer-free" strategies to fabricate polymeric micelles using polymer pairs as building blocks.These novel approaches result in noncovalently connected micelles(NCCM),in which intermolecular specific interactions(hydrogen bonding and hydrophobic interaction etc.) rather than chemical bonding exist between the shell and core.Being a substantial progress in the studies on NCCMs,in this dissertation we prepared micelles utilizing inclusion complexation between CDs and azobenzene.The dissertation is consisted of following parts.Firstly,we synthesized a series of azobenzene containing hydrophobic small molecules via four-step organic synthesis.In the selected solvents,we successfully constracted micelles by adding the hydrophobic molecule solution toα-、β-CD ware solution at certain temperature.TEM,DLS,SEM studies were carried out to confirm bilayer vesicle structure of aggregates which has average diameter of 200nm.When the aggregates were irradiated by certain intensity of UV light,the morphology of aggregates changed.TEM images showed that the bilayer structure converted to irregular aggregates. Following DLS measurements unfolded the obvious change in both particle scale and PDI index.The research on the mechanism of self-assembly tells us that the conformation of azobenzene will shift from trans to cis being irradiated by UV,which will exclude from CD cavity results in disassembly of vesicle formed irregular aggregates.When employing Visible light to irradiate UV-irradiated aggregates,we found that the transformation of Azobenzene group from cis to trans make the morphology of the aggregates changed from irregular aggregates to bilayer vesicles,whose shell have the average thickness of 10nm.We succesfully constracted NCCM via inclusion complexation and realized reversible conversion between vesicles and irregular aggregates with light stimuli.The second part of my work is the extension of previous work.We synthesized dendrons with Azo head groups as hydrophobic building blocks.We have succefully synthesized three kinds of Azo-dendrons with different generations G1-Azo、G2-Azo、G3-Azo.Then we modifiedβ-CD at 6-position and obtained mono-substituted OTs-CD. We successfully prepared EDA-CD using Mono-OTs-CD and ethane-1,2-diamine as reactant,the product can further react with 2-chloropropanoyl chloride formβ-CD ATRP initiator.Theβ-CD ATRP initiator can initiate the ATRP polymerization with monomer NIPAM,and formedβ-CD-PNIPAM as hydrophilic part.We found that THF can dissloved bothβ-CD-PNIPAM and G1-Azo.While the combined mixture ofβ-CD-PNIPAM and G1-Azo in THF were injected into water,micelle formed immediately.DLS measurements were employed to investigate the micelle solution and found that the average diameter of aggregates is 150～200nm and both the particle scale and PDI value would change with the increase of the concentration of the mixture solution.AFM and TEM were carried out and confirmed the morphology of the aggregates should be bilayer vesicle.In our opinion,the noncovalent inclusion complexation is the driving force to impel the Azobenzene part of G1-Azo into the cavity ofβ-CD,and formed amphiphilic molecule by noncovalent interaction.The interaction between dendrons can self-assemble to form bilayer vesicle and the structure can be stabilized by the hydrophilic PNIPAM.Subsequently we used UV and Vis light to irradiate the micelle respectively and realized the reversible change between hollow sphere to solid aggregates.In short,we have successfully synthesized block copolymer with noncovalent interaction and achieved reversible conversion between vesicles to irregular aggregates by light stimuli.The third part of my work is mainly focus on the synthesis research on the dendrimer built by noncovalent interactions.In recent years,dendrimers became the research interest in organic,macromolecular and material chemistry.However the dendrimers built up by inclusion complexations have not been reported yet.In our work, we designed two kinds of monomer A and B as building blocks.The monomer A consisted of one azobenzene and twoβ-CD;while The monomer B consisted of one adamantane and twoα-CD.Adamantane can be included inβ-CD easily and azobenzene is prone to be enclosed in the cavity ofα-CD in water.The noncovalent alternate dendrimer molecule can be formed by adding A and B respectively in water.The UV and Vis light irradiation would make the dendrimer molecule reversibly disassembly and assembly.The organic synthesis work is still in progress.The fourth part of my work is search on the microwave assisted synthesis of di arylsulfones and Aryl-alkyl sulfones.The microwave assisted coupling reaction of electrondeficient aryl halides with sulfinic acid salts through SNAr-based addition reactions to form diarylsulfones and Aryl-alkyl sulfones.By screened conditions,we synthesized 17 derivatives with high yield and shorten the reaction time from 16 hours to 10 minutes compared to the direct heating method.In the reaction using sodium methanesulfinate and 2-fluorobenzonitrile as reactant,we had discovered new product, and put forward the mechanism.更多还原