The Carbon Factory: A laboratory for the chemistry of carbon-rich systems

在采用摩尔定律的概念时，半导体行业通过提供巨大的计算能力，为40年的社会增长提供了保障。国际半导体技术路线图为研究人员提供了保持这种增长所需的短期和长期研究目标。2007年版的路线图预测，元件的几何尺寸将在10 - 15年内达到固态的极限，并强调了开发混合固态/分子器件的必要性。虽然自上而下方法的消亡的预测并不新鲜，但值得注意的是，半导体行业认可混合器件架构（即分子结构集成在CMOS器件中的架构）作为可预见未来的目标。为了应对这些挑战，需要对电子如何在分子结构内被操纵和在分子结构周围转移，以及如何将这样的系统固定到半导体表面上有一个牢固的理解。我们对分子内电子转移的大部分理解来自对线性化合物M（a）-B-M（B）的研究，其中两个位点，M（a）和M（B），除了电荷状态外，在各个方面都是相同的，是通过某种桥连结构B连接的。在过去的40年里，这些混合价化合物中分子内电子转移的基本原理已经被系统地绘制出来，位点M（a）和M（B）与桥B之间相互作用的重要性已经被清楚地确定。共轭富碳桥在M（a）和M（B）位间具有强耦合作用的混合价体系的构建中特别有用，线性碳桥混合价化合物中容易的电子转移过程使其在电子器件应用中成为分子尺度导线的重要组成部分。然而，可以合理地认为，分子大小的导线是不够的，如果要实现相对于传统固态器件的真正优势，则必须将更高级别的功能并入分子组件中。二维和三维分子系统中的电荷转移概念从设计晶体管型分子电子元件和分子开关的分子材料的角度引起了人们的注意，其中一个位点的状态可以影响其他位点之间相互作用的性质。多位混合价复合物已被提出作为构建基于量子元胞自动机（QCA）的逻辑门和存储单元的元素。尽管分支（例如X和Y形）混合价体系的概念简单，但已证明难以制备允许多个（多于两个）远程位点之间的强电子耦合的分支配体核，并且对这些体系中的电荷转移机制知之甚少。与线性M（a）-B-M（B）体系相反，特征为多于两个氧化还原位点的混合价体系（为了方便，在此称为多位点）没有得到很好的表示，并且通常限于线性阵列M（a）-B-M（B）-B-M（c）。该提案旨在开发与支化碳基桥连配体和多位点混合价化合物相关的合成化学，研究这些2-D共轭化合物内的电子转移，以及这些复合物可以附着到半导体表面的机制。一些侧边项目也被描述，这引发了新的调查线在化学的较长的累积，富碳的有机金属化合物在合成富勒烯和碳纳米管，分散液晶组成的氧化还原活性介晶和电子转移反应中的作用的振动耦合的作用。

In adopting the concept of Moore's Law , the semiconductor industry has underwritten 40 years of societal growth through the provision of immense computing power. The International Technology Roadmap for Semiconductors informs researchers of short and long-term research targets necessary to maintain this growth. The 2007 edition of the roadmap predicts geometric scaling of components will reach the limits of the solid state in 10 - 15 years, and highlights the need to develop hybrid solid-state / molecule devices. Although forecasts of the demise of the top down approach are not new, it is remarkable to see the semiconductor industry endorse hybrid device architectures (i.e. those in which molecular structures are integrated within a CMOS device) as targets within the foreseeable future. To meet these challenges, a firm understanding of how an electron can be manipulated within and transferred around a molecular structure will be required, and how such systems can be immobilised onto semiconductor surfaces will be required.Much of our understanding of intramolecular electron transfer originates from studies of linear compounds M(a)-B-M(b) in which two sites, M(a) and M(b) identical in every respect except charge state, are linked by some bridging structure, B. The fundamental principles of intramolecular electron transfer in these mixed valence compounds have been systematically mapped over the last 40 years, with the importance of the interactions between the sites M(a) and M(b) and the bridge B being clearly identified. Conjugated carbon-rich bridges have been identified as being particularly useful in the construction of mixed-valence systems with strong coupling interactions between the M(a) and M(b) sites.The facile electron transfer processes in linear, carbon-bridged mixed-valence compounds have led to significant interest in such systems as molecular-scale wires in electronic device applications. However, it could be reasonably argued that a molecular-sized wire is not sufficient, and higher-level function must be incorporated into the molecular component if true advantages over conventional solid state devices are to be realised. The concepts of charge-transfer in 2-D and 3-D molecular systems have attracted attention from the point of view of designing molecular materials for transistor-like molecular electronic components and molecular switches in which the state of one site can influence the nature of the interactions between the others. Multi-site mixed-valence complexes have been proposed as elements for the construction of quantum cellular automata (QCA)-based logic gates and memory cells. Despite the conceptual simplicity of branched (e.g. X and Y shaped) mixed-valence systems, it has proven difficult to prepare a branched ligand core that permits strong electronic coupling between multiple (more than two) remote sites, and relatively little is known about the mechanisms of charge transfer in these systems. In contrast to linear M(a)-B-M(b) systems, mixed valence systems featuring more than two redox sites, termed here multi-site for convenience, are not well-represented, and generally limited to linear arrays M(a)-B-M(b)-B-M(c). This proposal sets out to develop the synthetic chemistry associated with branched carbon-based bridging ligands and multi-site mixed-valence compounds, studies of electron-transfer within these 2-D conjugated compounds, and mechanisms through which these complexes can be attached to semi-conductor surfaces. A number of aside projects are also described, which initiate new lines of investigation in the chemistry of the longer cumulenes, the role of carbon-rich organometallics in the synthesis of fullerenes and carbon nanotubes, discotic liquid crystals comprised of redox-active mesogens and the role of vibrational coupling on electron-transfer reactions.