从超分子聚合物到超分子有机框架:组装溶液相超分子结构的周期性

单体分子在溶液相自发形成周期性的网络结构,是超分子化学和分子自组装研究领域的重大挑战.多头基分子在溶液相通过分子间非共价键作用可以形成超分子聚合物.提高多头基(三头基和四头基)分子骨架的刚性,可以提高结合位点的结构预组织,进而增强分子间相互作用的协同性和多价性特征,提高自组装结构的有序性或周期性.本文综述了多头基分子自组装形成超分子聚合物的一些重要进展,介绍了二维超分子有机框架(一类新的溶液相周期性自组装网络结构研究的最新进展.     

二维有机组装体的可控制备

二维有机组装体是一类具有特殊形貌和性质的有序结构, 有可能带来新功能和光电子领域的潜在应用, 但如何实现二维有机组装体的可控制备是尚待解决的问题. 针对这一问题, 我们通过对构筑基元的理性设计, 调控分子间的相互作用, 发展了三种可控制备二维有机组装体的新方法: (1)利用疏水有机阴离子作为Bola型两亲分子的抗衡离子, 能够削弱亲水头基间的静电排斥作用, 从而诱导两亲分子的组装结构从一维向二维转变; (2)基于非共价键形成超两亲分子, 通过设计和控制超两亲分子的拓扑结构, 简便有效地实现二维组装体的制备; (3)通过共价修饰或引入新的非共价键, 以限制三维结构在某一方向上的生长, 从而降低三维结构的维度, 也能实现二维组装体的可控制备. 未来, 上述研究有望进一步拓展, 并实现功能二维有机组装体的构筑.     

有机阳离子-无机多阴离子复合物:高分子体系中的组装及其自组装

有机阳离子包覆多金属氧簇无机多阴离子形成的具有确定化学组成、两亲性核壳结构超分子复合物,具有易于调控和集成有机和无机组分结构与功能的特性.以此类复合物为预组装体的自组装和高分子功能杂化材料展现了一类具有多方面构筑超分子组装体的新型构筑基元体系.如何实现预组装体复合物在结构稳定、具有良好加工性基材中的组装和功能化成为这一领域的重要研究内容.本文系统地总结了基于此类超分子复合物的高分子纳米复合材料和溶液中组装方面的研究进展与发展趋势.     

光调控一维/二维纳米组装体的可逆转换

正控制生物分子组装成具有特定形貌和功能的纳米组装体是当今材料化学和超分子化学的研究热点~1。目前,科学家通过分子自组装构筑了大量形貌各异的超分子组装体,并对其性能进行了探究;其研究重点主要集中在控制组装体的组装和解组装。如何有效的控制分子组装成特定的组装体面临着重大挑战,但对拓宽超分子材料的应用具有重要的促进意义~2。最近,南开大学元素有机国家重点实验室刘育教授课题组构筑了能够可逆转换的一维纳米管     

利用四重氢键和主客体作用构筑超分子共聚物（英文）

合成了一种同时含有脲基嘧啶酮基团(UPy)和苯并21冠7基团(B21C7)的单体H以及一种同时含有两个二烷基铵盐单元的单体G.分子H和G中的功能基团均由短间隔基相连. H可以通过四重氢键形成二聚体,进而和G发生主客体组装形成线性超分子共聚物.对该超分子共聚物进行了如下表征:随浓度变化1H NMR,粘度测试以及扫描电子显微镜(SEM)等.该结果将启发在更多领域中利用正交策略构筑各种超分子聚合物智能材料.     

精准宏观超分子组装

宏观超分子组装是近年来超分子科学的新兴研究方向,其本质是表面修饰有大量超分子官能团的宏观构筑基元的界面组装.由于组装过程中存在较多热力学亚稳态,导致最终产生大量非精准组装体,整体结构有序度低,制约了其在高性能超分子材料方面的应用,因此,如何实现精准宏观超分子组装,构建有序超分子结构,成为了制约宏观超分子组装发展的瓶颈问题之一.本专论从宏观超分子组装的概念与组装机制出发,根据宏观超分子组装过程的特点,分析阐述了组装体中存在不同界面匹配度的热力学亚稳态的问题;继而,从能量面的角度展开分析,总结和归纳了提高组装结构有序度的精准组装策略,包括:(1)利用组装体热力学稳定性差异,设计各向异性构筑基元诱导目标组装结构的形成,发展自纠错策略提高组装界面匹配度;(2)引入宏观构筑基元的组装动力学设计,使构筑基元发生自驱动运动并通过界面长程力取向,使组装界面达到高度匹配,实现近热力学平衡态的精准组装,直接获得精准结构.进而,结合精准宏观超分子组装制备的有序结构,我们展望了其在构建组织工程支架方面的应用前景.     

基于冠醚衍生物的超分子聚合物

自组装现象是生命科学最本质的内容之一,生物体系可以精确地利用非共价键相互作用形成高度有序的功能组装体.受到大自然的启发,近年来利用分子自组装构筑包括超分子聚合物在内的有序聚集体是超分子科学的研究热点.此类组装体不仅在拓扑学上具有重要的意义,而且可以用来制备动态的超分子功能材料.冠醚作为第一代超分子主体化合物,由于其结构...     

基于芳香分子-糖类手性超分子组装体及功能

手性超分子组装体广泛存在于自然界中,因其在材料、化学和生物学等领域广阔的应用前景,引起了科学家们极大的兴趣。其中以糖类分子作为手性源,经分子自组装构筑手性超分子组装体的研究已成为超分子化学领域的研究热点之一。本文综述了基于糖类修饰的苝酰亚胺分子、偶氮苯分子、联苯类分子和卟啉类分子等芳香分子化合物经自组装构筑的手性超分子组装体,介绍了其在有机溶剂和水的混合溶剂、水中的凝胶性质,超分子手性特征和功能,糖分子类型与超分子组装体手性间的关系等,并对基于糖类的手性超分子组装体的前景进行了展望。     

基于非共价镊合作用的线形超分子聚合物

基于"镊合导向自组装"策略构筑超分子聚合物,可实现电子给受体基元在组装体层次的精确排列,设计并制备了基于三联吡啶铂(Ⅱ)炔分子镊子主体的AA型单体分子,以及基于芘客体的BB型单体分子.通过在芘客体上引入酰胺基元,在非共价镊合过程中可产生分子间NH―N氢键作用.通过氢键和供受体相互作用力的高效协同,显著提高了非共价镊合体系的结合强度,其结合常数可达到(3.58±0.01)×105(mol/L)?1,相比于未取代芘客体,其结合强度呈现出2个数量级的显著提高.在此基础之上,对AA、BB型单体分子的超分子聚合行为展开了深入的研究.结合实验及理论计算,证实在高浓度状态下,两单体分子通过自组装可获得具有高分子量特征的线形超分子聚合物.同时,考察了超分子聚合物的动态可逆性,通过温度的改变及链终止剂的加入,可实现超分子聚合物的可逆自/解组装过程.     

表面印迹交替层状组装薄膜

在简要概述非常规交替层状组装这一进展后,重点总结了如何利用非常规交替层状组装以实现表面印迹膜的制备.模板分子与聚电解质在溶液中组装形成超分子复合物,然后以此超分子复合物为构筑基元,与感光性高分子,如重氮树脂,通过常规交替层状组装形成聚合物多层膜.利用聚合物多层膜之间的光化学反应形成稳定的多层膜,然后去除模板分子得到分子...     

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.     

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.     

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.     

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.     

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.     

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.