茂铁类单分子结电子传输性质的研究进展

Research Progress of Electron Transport Properties in Ferrocene-Containing Single-Molecule Junctions

分子导线是构成分子器件的关键部分,它的发展有望解决未来将要面临的电子器件尺寸即将达到理论极限而无法满足人们更高需求的问题.茂铁类分子凭借优秀的物理、化学性质被广泛应用于非线性光学、分子电子学等领域.在过去的十多年里,茂铁基团的引入构建了多种结构新颖的分子导线,为单分子器件的基础研究做出了巨大贡献.然而对于茂铁类分子导线的研究,大多集中于其异茂环取代的衍生物,同茂环取代的衍生物因合成较为困难,并没有受到研究者们的关注.根据分子的结构特征,将茂铁类分子导线分为π共轭型与非π共轭型两大类.以分子的构效关系为主线,对近十几年来茂铁类单分子结电子传输性质方面的工作进行了概括与总结,期望为未来茂铁类分子导线的研究提供借鉴.

The development of molecular wires,the key component of molecular devices and the bridge and link between electrodes,is expected to solve the problem of future electronic devices that are reaching their theoretical size limit and cannot meet the higher demands of the population.After a long period of development,molecular wires are no longer limited to the basic stages of synthesis and modification.In recent years,the exploration of the practical functions of molecular wires has been a major focus of research in molecular electronics.Ferrocene has been widely used in the fields of nonlinear optics and molecular electronics due to its excellent physical and chemical properties.In the past decade or so,the introduction of ferrocene groups has led to the construction of a variety of novel molecular wires,which have significantly contributed to the basic research of single-molecule devices.The molecular wires based on ferrocene groups have several advantages over conventional pure organic molecular wires,including(1)reducedπ-πstacking between molecules,(2)adjustable molecular lengths and flexibility,(3)reduced front-line molecular orbital energy differences,which improves the electron transfer capability of molecular wires,and(4)inherently good conductive properties,which allow direct interaction with gold electrodes to form singlemolecule junction.However,most of the research on ferrocene-based molecular wires has focused on their 1,1'-substituted derivatives,while their 1,3-substituted derivatives have not received much attention due to the difficulty of their synthesis.Based on the structural properties of the molecules,metallocene molecular wires are classified into two types:π-conjugated and nonπ-conjugated.The work on the electron transport properties of ferrocene-containing single-molecule junctions in the last decade is summarized in terms of the conformational relationships of the molecules,in the hope of providing a reference for future research on ferrocene molecular wires.