金属-有机分子笼催化剂的近期研究进展

酶因在催化过程中展现出特异的选择性和活性而备受关注.在配位自组装过程中,通过调节金属结点的种类和有机配体结构,金属-有机分子笼（MOCs）的空腔可获得多种作用力协同的特殊环境.近年来,对于超分子反应器的研究显示,其空腔结构类似于生物酶,能在催化过程中展现出非常高的反应速率、空间和立体选择性,这一特性引起了科学家们的研究兴趣.文章就近两年MOCs在催化方面的应用研究进展进行了综述.     

稀土金属有机分子笼的研究进展

金属有机分子笼(MOCs)在主客体化学、催化、光学生物成像等众多领域表现出潜在的应用价值,从而引起众多科学家的研究兴趣.稀土金属超分子配位体系由于其独特的光学和磁学特点使众多超分子学者关注和研究.基于配体的设计,综述了不同构型的稀土金属有机分子笼的构筑以及它们在光、磁、催化等方面的应用.     

有机分子笼封装金属纳米团簇的合成策略与催化应用

金属纳米团簇是由若干金属原子组成的纳米材料,尺寸介于单个金属原子和纳米颗粒之间,具有独特的几何和电子结构,在催化反应中展现出良好的性能.然而裸露的金属纳米团簇由于表面能较高,在催化过程中容易聚集失活.近年来,有机分子笼(organic molecular cages,OMCs)作为一种新兴的多孔材料受到了广泛关注.将金属纳米团簇封装在有机分子笼的限域空间内不仅可以提高其粒径均一性,还可以提高稳定性.有机分子笼的孔道结构完全开放,封装在其内部的金属纳米团簇在氧化、还原、偶联、产氢等反应中仍保持较高的催化活性.本文简要总结了有机分子笼封装金属纳米团簇的合成策略以及这类材料在催化领域的应用.     

C60碳笼分子的结构和性质

本文介绍了新近发现的Ｃｎ碳原子簇分子中的Ｃ６０碳笼分子，讨论了它的结构，性质和反应。     

富勒——Cn碳笼分子命名的词源

Ｃｎ碳笼分子又称巴基米斯特富勒烯、富勒烯等，是根据这类分子结构与美国建筑师、工程师理查德．巴基米斯特．富勒设计的穹顶建筑结构相似，由该建筑师的名字演变而来。     

醇的水溶解性与分子分支程度的关系

从分子图的二步数和三步数计算醇分子的分支指数（MBI）,将MBI和碳原子数Nc一起对50个醇的水溶解性进行定量相关,得到的相关方程为 -log S = -2.510 8＋0.571 4 Nc -0.394 0 MBI,其相关系数r=0.985 0, 标准偏差s=0.185,完全落在实验误差（0.4 lg 单位）范围之内.所得方程具有良好的估算精度和明确的物理意义.     

有机分子磁体的研究进展

在大量文献的基础上对有机分子磁体进行分类，从有机分子铁磁体、有机金属分子铁磁体和无机分子铁磁体三个方面介绍了有机分子磁体的最新研究进展。     

膨润土多孔有机改性及其影响因素

以信阳膨润土为原料,将碳粉和淀粉按一定比例混入其中,挤压造粒,高温灼烧,再进行有机物覆盖,得多孔有机膨润土.讨论了有机覆盖剂的种类、覆盖体系的温度、pH值及碳粉的含量对PO43-吸附性能的影响.当用十六烷基三甲基氯化铵做覆盖剂,碳粉的含量为3.5%时,溶液体系的pH值为7-8,覆盖温度80℃时,吸附率达91.2%.     

多孔有机膨润土的合成及其影响因素

以信阳钠基膨润土为原料,将易燃性微粉和淀粉按一定比例混入其中,挤压造粒,高温灼烧,再进行有机物覆盖,得多孔有机膨润土,并将其用于对PO43-的吸附.讨论了易燃性微粉的种类、煤粉和淀粉以及覆盖剂的用量及焙烧温度等因素对PO43-吸附性能的影响.结果表明:用煤粉作造孔剂,煤粉和淀粉的含量分别为5%、2%,有机覆盖剂的用量为45%时,焙烧温度550℃时吸附率达89.2%.     

Modular and predictable assembly of porous organic molecular crystals

Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitation for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules.     

有机手性分子器件的光电特性

目前多种有机手性分子器件虽已研制成功,但其内在的物理机理仍有许多未解之谜,其中手性分子的圆二色性精细结构、手性诱导的自旋选择效应等是有机手性分子研究的核心.为设计基于手性的新型有机功能器件提供理论指导,考虑有机手性分子螺旋势场诱导的自旋-轨道耦合,围绕分子的光电特性及其调控展开了系列研究.根据光致跃迁理论,得到手性分子...     

一种基于噻吩的共轭有机多孔聚合物的合成及其光催化性能研究

共轭多孔聚合物(CPPs)具有扩展的共轭体系和多孔性,是一种具有广阔应用前景的非均相无金属光催化剂.本文中,我们报道一种基于噻吩的有机多孔聚合物的设计和制备,首先利用Suzuki偶联反应合成出单体3,3',5,5'-四(噻吩-2-基)-1,1'-联苯,再以三氯化铁为催化剂催化噻吩偶联,成功制备一种共轭有机多孔聚合物(PTB).这种聚合物光吸收可达到800 nm,比表面积为699.8 m~2·g~(-1),并且中孔和微孔共存.在非均相体系中,这种催化剂对胺氧化偶联表现出有效的光催化性能,反应产率可达94%,并且亚胺为其唯一产物.     

White organic light-emitting devices fabricated by spin-coating molecular materials

White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former formed by spin-coating solution containing MH of NPB (N.N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) and MADN (2-methyl-9,10-di(2-naphthyl) anthracene),blue dye (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and yellow dye (5,6,11,12-tetraphenylnaphacene).The performances of the de...     

Low-voltage organic transistors with an amorphous molecular gate dielectric

Organic thin film transistors (TFTs) are of interest for a variety of large-area electronic applications, such as displays, sensors and electronic barcodes. One of the key problems with existing organic TFTs is their large operating voltage, which often exceeds 20 V. This is due to poor capacitive coupling through relatively thick gate dielectric layers: these dielectrics are usually either inorganic oxides or nitrides, or insulating polymers, and are often thicker than 100 nm to minimize gate leakage currents. Here we demonstrate a manufacturing process for TFTs with a 2.5-nm-thick molecular self-assembled monolayer (SAM) gate dielectric and a high-mobility organic semiconductor (pentacene). These TFTs operate with supply voltages of less than 2 V, yet have gate currents that are lower than those of advanced silicon field-effect transistors with SiO2 dielectrics. These results should therefore increase the prospects of using organic TFTs in low-power applications (such as portable devices). Moreover, molecular SAMs may even be of interest for advanced silicon transistors where the continued reduction in dielectric thickness leads to ever greater gate leakage and power dissipation.     

N-doped porous graphene for carbon dioxide separation: a molecular dynamics study

Using molecular dynamics simulations, it is shown that N-doped porous graphene membrane can efficiently separate CO₂ from the CO₂/CH₄ mixture. The effects of pore rim modifications, N-doping sites, initial gas pressure, and feed gas compositions on CO₂ separation performance of N-doped porous graphene membrane are also examined. It is found that gas permeability increases with increasing initial gas pressure or the feed gas percentages. Pore rim modifications with nitrogen atoms (pyridinic N) can significantly improve the selectivity of CO₂ over CH₄ owing to the enhanced electrostatic interactions compared to the unmodified one, and the all-N-modified pore-16 shows the highest CO₂ selectivity over CH₄ (~29). Doping N atoms on the graphene sheets (quaternary N) has little effect on the CO₂ selectivity. Our study demonstrates that the N-doped porous graphene is an excellent candidate for CO₂ separation, which may be beneficial for the realization of a low carbon society.     

N-doped porous graphene for carbon dioxide separation： a molecular dynamics study

Using molecular dynamics simulations, it is shown that N-doped porous graphene membrane can efficiently separate CO2 from the CO2/CH4 mixture. The effects of pore rim modifications, N-doping sites, initial gas pressure, and feed gas compositions on CO2 separation performance of N-doped porous graphene membrane are also examined. It is found that gas permeability increases with increasing initial gas pressure or the feed gas percentages. Pore rim modifications with nitrogen atoms （pyridinic N） can significantly improve the selectivity of CO2 over CH4 owing to the enhanced electrostatic interactions compared to the unmodi- fied one, and the all-N-modified pore-16 shows the highest CO2 selectivity over CH4 （- 29）. Doping N atoms on the graphene sheets （quaternary N） has little effect on the CO2 selectivity. Our study demonstrates that the N-doped porous graphene is an excellent candidate for CO2 separation, which may be beneficial for the realization of a low carbon society.     

TTF-CA有机分子晶体多铁性的数值研究

基于一维派尔斯-哈伯德模型,采用数值精确对角化和约束路径量子蒙特卡罗数值方法,研究有机分子晶体TTF-CA（tetrathiafulvalene-p-chloranil）的多铁性特征.当填充电子数与格点数相等时（即半填充）,两种方法的计算结果表明,在一定的参数空间体系存在反铁磁和铁电极化共存的多铁状态.在弱电子关联区间,数值计算结果与哈特利-福克平均场得到的结果一致.但在中等至强电子关联区间,数值结果预言,多铁性产生的电声子相互作用强度远低于平均场给出的结果.当填充电子数略低于格点数时,体系存在铁磁与铁电极化共存的状态.研究结果有助于理解和设计新型有机多铁性材料.