Molecules to materials

Design of molecular nonlinear optical materials is presented; their inherent advantages are highlighted and their current status appraised.     

Molecules to materials

With the advent of modern physics and chemistry, fundamentally new types of materials have been created in this century. Various types of forces operating in different classes of solids are exploited in the design of molecular materials. A variety of fabrication techniques have been developed to make materials with the desired properties. An overview of these aspects is provided in this article.     

Molecules to materials

Design and fabrication of molecular materials combines the versatility of synthetic chemistry and the fundamental insights into materials gained through condensed matter physics. This article presents several examples to illustrate the power of a molecular level approach to material properties. An overview of liquid crystals is presented followed by a brief account of molecular design for liquid crystal displays. The growth of organic semiconductors and metals, conducting polymers and organic superconductors is discussed next. Finally the basic aspects of the design of molecular conductors are analysed.     

Molecules to materials

The concept of individual molecules functioning as active devices has been around for a few decades. The active device size has continuously decreased during this century, starting with meter-sized vacuum valve tubes of the early 1930’s and 40’s, through millimeter-sized transistors in the 1960’s to micrometer-sized integrated circuits in the 1970’s and 80’s. Thus the molecular scale devices represent the logical evolution to nanoscale devices expected towards the end of this century and the beginning of the next. This article presents some examples to provide a glimpse of the activity in this area. An erratum to this article is available at .     

Molecules to materials

Earlier articles in this series provided several examples to illustrate the controlled assembly of bulk structures with desired solid state properties using specifically designed molecules. The ultimate goal of these exercises is the development of devices whose building blocks are molecules. This article and the next attempt to impart the flavour of this exciting field of research and technology through brief discussions of several molecular devices. This article will focus on devices, which utilise the bulk properties of molecular materials; the examples selected are electroluminiscent device, thin film transistor and an electro-optic device.     

Introducing Iranian Primary Children to Atoms and Molecules

Research in Science Education - In common with many other countries, the Iranian science curriculum does not introduce primary children to atoms and molecules but instead leaves the teaching of...     

纳米金胶体对吖啶橙水溶液的荧光增强效应

以纳米金胶体颗粒为增强衬底,观测了两种不同浓度的吖啶橙水溶液荧光信号的表面增强效应,并用激发光波长与金胶表面等离子体共振的匹配理论,以及近场增强理论解释了所观测到的现象.     

纳米银胶体表面的荧光增强效应研究

利用化学还原法制备了几种分布均匀的银纳米颗粒,并利用激光光谱法对吸附在银纳米颗粒表面的吖椗橙(AO)分子的荧光增强现象进行了研究探讨.探测了纳米银粒子的分布状态和尺寸对AO分子的荧光增强效应的影响.实验结果显示,当纳米银粒子的间距合适时,处于其附近的AO分子的荧光增强可以达到最佳效果.此外,随着颗粒尺寸的变大,荧光增强效应会更加明显.     

Humorous materials to enhance active learning

The use of humour in teaching and learning can be contentious, with some authors suggesting that the efficacy of humorous materials is mediated by the culture of the student. Nevertheless, humour represents a potential vehicle for the introduction of active learning in a classroom setting, as judicious use of humour may lead to a more relaxed learning atmosphere and greater student engagement. This article describes how humour was used to good effect in creating a suite of online materials designed to enhance the academic English skills of international students. The materials, funded through a grant from the Office for Learning and Teaching and now openly accessible on the English for Uni website, were developed using an action research process. This involved an iterative process of designing, trialling and evaluating the resources to ensure that humour was used appropriately. In the final stages, Biggs’ Structure of the Observed Learning Outcome taxonomy was also used to evaluate student learning. The results show that the materials improved students’ understanding of the topics presented on the site and that the element of humour stimulated student interest in learning.     

凤头,猪肚与豹尾:电视教材的制作

本文从电视教材的结构作为切入点，以电视教材的制作基础理论和实践为展开面，以总结经验和归纳论点为归宿点，讨论电视教材的制作。     

小分子抗癌新药nutlin-3的合成新法研究

以4-甲氧基-2-羟基苯甲醛和对氯苯甲醛为原料,采用7步反应初步合成了小分子抗肿瘤药物nutlin-3,TLC检测每一步反应,总收率40%。对中间体和目标产物的结构和纯度进行了IR和1H NMR表征。     

Molecules for converting sunlight into electricity

The dream of generating electricity from sunlight in large scale at low cost may not be that far from reality in this century. Rapidly emerging solar energy technology using low cost dye sensitized photovoltaic cells on plastics would be a real boost for the third world countries. Though the conventional silicon solar cells are efficient in converting solar energy into electricity until now, the non conventional solar cells based on molecular photosensitization by colored materials in wide band gap semiconductors is a fast growing field of basic scientific and industrial research. Present state-of-the-art cells using molecular dyes shows energy conversion efficiencies of 10–11%. In this article, we present the concept of dye-sensitized photovoltaic (DSPV) cell and the progress in current research. The important contributions of molecular dyes that are used as photosensitizers in these photovoltaic or solar cells are also described.     

分子学说的创立过程及科学方法研究

运用科学认识论和方法论,探讨了分子学说的创立过程及其方法特点,并与Fullerene化学创立过程进行比较得出了几点重要结论,对于未来化学研究具有积极的启发作用.     

Molecule Matters van der Waals Molecules

In Part 2 of this series, we discuss homo- and hetero-nuclear noble gas dimers. Experimental and theoretical results for dimers containing He, Ne, Ar, Kr and Xe are reviewed. These dimers are bound by London dispersive forces, which is one component of the van der Waals or intermolecular forces. Though these are usually called van der Waals complexes or van der Waals molecules, these dimers may be more appropriately called London molecules. Heliumdimer is a particularly interesting case with the equilibrium internuclear distance estimated to be about 50 Angstrom.     

钯钇氢分子结构与热力学性质

在钯Pd和钇Y原子相对论有效原子实势和基函数SDD下,使用密度泛函理论B3LYP方法计算得到钯钇氢气态分子的结构、光谱数据、能量E、熵S等性质．计算固体钯钇氢的E和S时,近似以气体分子的电子能和振动能代替固体分子的E,用电子熵和振动熵代替固体分子的S．在此近似条件下,计算了不同温度下的热力学函数及生成反应的标准焓变△H°、标准熵变△S°和标准自由能变△G°．结果表明：固体钯钇氢分子具有热力学稳定性．     

关于气体分子按麦克斯韦速度分布规律的推导

从气体分子速率分布函数出发,同时考虑速度的大小和方向,利用拉格朗日未定乘子法导出气体分子按麦克斯韦速度分布规律;并利用简单的体积元转换得到气体分子按麦克斯韦速率分布率。     

单分子导电性质的研究进展

介绍测量单个有机分子导电性质的一些进展,包括分子的尺寸效应,官能团效应,分子与电极的接触效应,以及分子逻辑器件的初步研究.     

调节植物发育的胞外信使分子

近年来，相继发现一些植物胞外分子如细胞壁钙调素、胞外Ca^2 、寡糖素和阿拉伯半乳聚糖蛋白（AGPs）等，它们都是重要的信号源，与植物的发育密切相关。胞外信使分子在植物发育中的重要作用的研究虽刚刚起步，但已受到人们的充分关注和重视。     

分子间斥力与引力的差别探究

学习了分子间作用力后,大多数学生都会有这样的疑问:分子是中性,为什么分子间即有斥力又有引力?它们是什么性质的作用力?分子间作用力的本质是什么?我想就这些问题做一下探究。我们知道分子可以构成物质,而分子又是由原子构成,原子是由原子核和核外高速运动电子构成,原子核带正电,核外电子带等量负电。无论组成分子的原子数量和结构如何,从课本上的示意图11-6曲线看,分子间斥子是库仑斥力。因为库仑斥力与距离的平方成反比,函数图象是双曲线,正好吻合。从分子的结构看库仑斥力来自于相邻分子的核外电子之间的斥力;原子核与原子核之间的斥力,…