宏观超分子组装——超分子材料制备新理念

近年来,宏观超分子组装已经逐渐发展成为超分子化学中的一个新兴研究方向.宏观超分子组装是指特征尺寸在微米及微米以上尺度的构筑基元,通过分子间相互作用发生组装,形成有序结构的过程,是实现"全尺度自组装"不可或缺的环节,为超分子体相材料的制备提供了新的理念和方案.本文从宏观超分子组装的发展概况、设计原则与策略和应用方向3个方面展开综述,介绍了从基于长程作用力的"宏观组装"到基于分子间相互作用的"宏观超分子组装"的区别与联系,阐释了实现宏观超分子组装的设计原则和相关机理.最后,针对实现超分子材料广泛应用的目标,从"精准组装"的角度综述了提高组装结构有序程度的方法,以及宏观超分子组装在组织工程支架等方面的应用前景.     

两亲性杯芳烃的超分子自组装

本文综述了两亲性杯芳烃分子在不同维数下组装研究的进展,主要包括零维组装(囊泡、胶束、树枝状分子和分子箱)、一维组装(纳米管,纳米线及纤维)和二维组装(LB膜、超薄分离膜及界面组装);探讨了不同维数下组装体的形成机理和驱动力,主要包括氢键作用、金属配位作用、静电作用、包结络合作用以及疏水相互作用;控制和调节不同维数下组装体的转变,有助于组装体材料在许多方面的应用。     

金-硫键自组装生物分子膜

应用硫原子与金表面的强烈相互作用,可获得具有特定功能的生物分子自组装膜,在生物学、药理学及仿生学方面有重要的研究意义。本文着重介绍了一些相关的生物分子自组装体系,包括葡萄糖氧化酶、类脂、核酸传感器等在金基底表面的自组装。     

固体表面分子的自组装结构与调控机制

固体表面有机分子自组装是合成低维超分子材料和对固体表面进行功能化的重要途径.本文主要介绍了利用理论计算与扫描隧道显微镜实验相结合的手段研究固体表面分子自组装机制及结构与物性调控的相关工作.主要聚焦于几种由弱相互作用主导的分子自组装过程,从影响固体表面功能分子自组装过程的基本要素出发,如固体表面性质、功能分子的结构、功能分子间相互作用的类型和强度以及有卤族元素增原子参与的组装等,介绍了这些要素在构筑并调控分子自组装结构中的作用,理解固体表面功能分子自组装结构的调控机制,最后对如何实现分子自组装结构及物性的可控调制进行了展望,为设计新型低维超分子网格结构提供思路.     

Fmoc-FF二肽分子自组装过程的分子动力学研究

采用分子动力学方法模拟研究了Fmoc-FF二肽分子在溶液中的自组装过程,探究了自组装过程中的驱动力及水桥结构对聚集体稳定性的影响.结果表明,Fmoc-FF二肽分子可以在水溶液中自组装形成结构规整的圆柱形纳米棒;根据Fmoc环间的径向分布函数,通过比较二肽分子之间及二肽分子与水分子间的相互作用,推测二肽分子间的π-π相互作用是自组装过程的主要驱动力;另外的驱动作用体现在二肽分子与水分子之间形成的氢键,其中水分子以水桥结构连接不同的二肽分子,这种水桥结构对自组装结构具有稳定作用.     

基于杯芳烃主体的分子自组装研究进展

分子自组装是超分子化学最重要的研究内容之一. 杯芳烃作为继冠醚、环糊精之后的第三代人工合成受体分子已在分子自组装研究方面取得了重要进展并显示了广泛的应用前景. 主要综述杯芳烃衍生物通过氢键、金属诱导配位、π-π作用、疏水作用等非共价键弱相互作用力在溶液状态、固态和界面的分子自组装方面的研究进展.     

液/固界面多肽分子组装精细结构的扫描隧道显微镜研究

介绍了与蛋白构象病相关的淀粉样多肽分子组装结构的研究进展.综述了在固体、溶液以及界面等不同状态下多肽分子组装结构的表征方法,对于扫描隧道显微技术(STM)在解析多肽分子界面组装结构方面的研究进展进行了重点评述,主要包括在液/固界面上的多肽分子组装结构的精细特征,界面诱导的多肽构象转变,调节分子、染料等与多肽组装结构的相互作用模式和位点识别等.     

基于中性芳环间电子供体-受体相互作用驱动的有机超分子组装

综述了近年来中性单体分子之间的供体-受体相互作用在超分子自组装研究中的应用.首先介绍了应用广泛的典型中性芳环富电子和缺电子体系的种类,然后重点介绍了DAB和DAN作为富电子单元,PDI和NDI作为缺电子单元的供体-受体相互作用在互相锁链的超分子体系,非天然分子折叠体和二聚体组装方面的应用进展.     

甘脲类分子胶囊受体合成方法的研究进展

甘脲类分子胶囊是一类独特的由非共价键弱相互作用力组装而成的人工受体, 在分子识别、自组装、分子微反应器、智能材料等方面得到了广泛而深入的研究. 系统综述了网球型(Tennis ball)、垒球型(Softball)、足球型(Football)及圆盘型(Jelly Doughnut)等分子胶囊的合成方法.     

四重氢键自组装体系的设计与应用

氢键是自然界中最基本的分子间弱相互作用力之一,是构筑超分子自组装体系的理想推动力。近年来,构筑性能优良的多重氢键组装体系已经成为超分子化学的一个热门研究领域。其中,四重氢键组装体系因具有较强的结合力、合成简单、结构易于修饰以及可预测的识别性能等优点,在构筑超分子组装体方面得到了广泛应用。本文综述了四重氢键组装体系的研究进展,重点介绍了各类四重氢键体系的设计思路及其应用。     

Nitrenium Salts in Lewis Acid Catalysis

Molecular compounds featuring nitrogen atoms are typically regarded as Lewis bases and are extensively employed as donor ligands in coordination chemistry or as nucleophiles in organic chemistry. By contrast, electrophilic nitrogen‐containing compounds are much rarer. Nitrenium cations are a new family of nitrogen‐based Lewis acids, the reactivity of which remains largely unexplored. In this work, nitrenium ions are explored as catalysts in five organic transformations. These reactions are the first examples of Lewis acid catalysis employing nitrogen as the site of substrate activation. Moreover, these compounds are readily accessed from commercially available reagents and exhibit remarkable stability toward moisture, allowing for benchtop transformations without the need to pretreat solvents.     

Structure and growth of self-assembling monolayers

The structural phases and the growth of self-assembled monolayers (SAMs) are reviewed from a surface science perspective, with emphasis on simple model systems. The concept of self-assembly is explained, and different self-assembling materials are briefly discussed. A summary of the techniques used for the study of SAMs is given. Different general scenarios for structures obtained by self-assembly are described. Thiols on Au(1 1 1) surfaces are used as an archetypal system to investigate in detail the structural phase diagram as a function of temperature and coverage, the specific structural features on a molecular level, and the effect of changes of the molecular backbone and the end group on the structure of the SAM. Temperature effects including phase transitions are discussed. Concepts for the preparation of more complex structures such as multi-component SAMs, laterally structured SAMs, and heterostructures, also with inorganic materials, are outlined. The growth and ways to control it are discussed in detail. Solution and gas phase deposition and the impact of various parameters such as temperature, concentration (in solution) or partial pressure (in the gas phase) are described. The kinetics and the energetics of self-assembly are analyzed. Several more complex issues of the film formation process including non-equilibrium issues are discussed. Some general conclusions are drawn concerning the impact of various molecular features on the growth behavior and concerning the relationship between growth and structural phase diagram. Finally, the potential of self-assembly as a route for the preparation of monolayers with pre-designed properties and SAMs as building blocks in heterostructures as well as application strategies are discussed.     

Chemical reaction and Soret effects on MHD convective flow of second grade fluid through an absorbent medium with ramped wall temperature as well as ramped surface concentration

In the present paper, the heat generating and/or absorption as well as thermo-diffusion on the unsteady free convection MHD gyrating flow of radiation and chemical reactive second grade fluid past an unbounded perpendicular plate during absorbent medium have been discussed. Here, it is assumed that, the confining plate has the ramped wall temperature with ramped surface concentration and isothermal temperature with ramped surface concentration. The analytical solutions for the governing equations are found by utilization of Laplace transformation methodology. The velocity, temperature and concentration profiles are analyzed with quite few figures. It is determined that, velocity, temperature and concentration distribution sketches in case of ramped temperature as well as ramped surface concentration are not as much of as those of isothermal temperature as well as ramped surface concentration. In addition to the idioms of skin friction, Nusselt number as well as Sherwood number are achieved and characterized numerically with tabular format.     

A Chemical History of Polycyclic Musks

Musk odorants are ubiquitous in fine perfumery as well as household products, and are divided into four main families, the nitromusks, the macrocyclic musks, the polycyclic aromatic musks, and the alicyclic musks, following their order of appearance on the perfumery market. This article presents the scientific and industrial adventures during the discovery of the seven commercial polycyclic musks, which invigorated the aroma chemistry corporations during the second half of the 20th century, resulting in relentless competition. Research and development strategies are exposed, and reactivity, analytical, mechanistic, and structure–activity relationships aspects are discussed as well as some biographical elements of the main scientific actors, and some fine perfumery examples are given as illustrations of their use.     

锂离子电池有机硅电解液

有机硅电解液具有优良的热稳定性、低可燃性、无毒性、高电导率和高分解电压等优点,近年来成为了锂离子电池新型电解液的研究热点。本文综述了有机硅电解液的研究进展,重点介绍了聚醚有机硅电解液的设计合成、物理化学性能、与电解质盐和电极材料的匹配性关系及其在电池中的性能表现;简述了有机硅功能化电解液添加剂的研究进展,如成膜添加剂、阻燃添加剂、吸酸吸水添加剂等;最后对有机硅电解液的进一步研究趋势和应用前景进行了展望。     

Eka-elements as chemical pure possibilities

From Mendeleev’s time on, the Periodic Table has been an attempt to exhaust all the chemical possibilities of the elements and their interactions, whether these elements are known as actual or are not known yet as such. These latter elements are called “eka-elements” and there are still some of them in the current state of the Table. There is no guarantee that they will be eventually discovered, synthesized, or isolated as actual. As long as the actual existence of eka-elements is predicted, they cannot be considered as actual but only as purely possible. Given that eka-elements are chemical pure possibilities, a possibilist approach, entitled “panenmentalism,” can gain support as well as an important implication.     

Bethe ansatz of electrons as a mean-field wavefunction for chemical systems

Eigenvectors of a Hamiltonian solvable by a Bethe ansatz (BA) are employed as a variational trial wavefunction for electrons. Energy expressions are developed showcasing the methods of BA. Numerical results are presented for atomic systems as well as molecular dissociations, which are numerically identical with the restricted Hartree-Fock (HF) results. The present contribution serves as a bridge between HF and other BA wavefunctions to be employed as mean-field methods for strongly correlated electrons.     

Effect of phosphate activating group on oligonucleotide formation on montmorillonite: the regioselective formation of 3',5'-linked oligoadenylates

The effects of amine structure on the montmorillonite-catalyzed oligomerization of the 5'-phosphoramidates of adenosine are investigated. 4-Aminopyridine derivatives yielded oligoadenylates as long as dodecamers with a regioselectivity for 3',5'-phosphodiester bond formation averaging 88%. Linear and cyclic oligomers are obtained and no A5'ppA-containing products are detected. Oligomers as long as the hexanucleotide are obtained using 2-aminobenzimidazole as the activating group. A predominance of pA2'pA is detected in the dimer fraction along with cyclic 3',5'-trimer; no A5'ppA-containing oligomers were detected. Little or no oligomer formation was observed when morpholine, piperidine, pyrazole, 1,2,4-triazole, and 2-pyridone are used as phosphate-activating groups. The effects of the structure of the phosphate activating group on the oligomer structure and chain lengths are discussed.