含羧酸根配位的双金属单元分子链的表面可控组装及电学性质研究

Fabrication of molecular junctions and understanding the relationship between their structures and electron transport properties are of primary importance to the development of applicable molecular electronic devices. However, previous studies mostly focused on directly synthesized organic short molecules, whose molecular and electronic structures are difficult to control precisely. This leads to difficulties in establishing clear relationships between structures and electron transport properties of molecular electronics. Herein we plan to fabricate a series of metal-organic hybrid molecular wires on electrode surfaces by stepwise assembly methods using M2(RCOO)4 (M = Rh, Ru, Pd, Cu, Zn, etc.) units, of which the composition, structure, length and energy level can be precisely controlled. Their electronic properties will be characterized by electronic spectroscopy, electrochemical analysis and so on. Furthermore, the electron transport behavior will be investigated by various methods, such as conductive probe atomic force microscopy. Quantitative factors including electron transfer rate constant, zero-distance electron transfer rate constant, distance attenuation factor, and rectification ratio will be measured. We expect to discover the effects of molecular wire compositions and electronic structures on the electron transport behavior, in order to set up a quantitative relationship between the structures and long-range electron transport properties of the molecular wires. The electron transport mechanism through these molecular wires will also be studied. The knowledge gained from the proposed project would provide deep understanding on regulation of electron transfer properties of such molecular wires, which is critical for the future development of molecular electronic devices with desired properties.

构筑金属/分子/金属结并明确分子结构与其电荷输运性能的关系是分子电子器件实用化的前提。目前用于构筑分子结的模型分子多为直接合成的有机短链分子，较难实现对其组成、结构的精确调控，不利于建立分子结构与其电学性能的明确关系。本项目拟设计并通过分步组装法制备基于羧酸根配位的双金属单元（M2(RCOO)4，M = Rh, Ru, Pd, Cu, Zn等）的，且组成、结构、长度可控并具有特定能级结构的分子链。利用紫外可见光谱、循环伏安、导电原子力显微镜等技术研究组装的分子链的电子光谱、电化学性质及电荷传输速率、电导随分子链长度的衰减、整流效应等电荷传输性能；探索分子链的组成、结构、能级等对其电荷输运性能的影响规律，建立分子链结构与其电荷传输性能间的构效关系，并探讨电荷输运机理。实现对此类分子链内电荷输运性质的精确调控，为未来设计制备具有特定性能的分子电子器件提供实验基础和理论指导。

构筑金属/分子/金属结并明确分子结构与其电荷输运性能的关系是分子电子器件实用化的前提。本项目通过分步组装法制备了多种组成、结构、长度可控的基于羧酸根配位的双金属单元（Rh2(RCOO)4，R = H, F, CH3）的分子链。利用紫外可见光谱、电化学、原子力显微镜等方法对由上述分子链构成的单分子膜进行了表征，并利用导电原子力显微镜等技术研究组装的分子链的电荷传输性能；探索分子链的组成、结构、能级等对其电荷输运性能的影响规律。具体执行情况如下：1）在电极表面组装了一系列组成、结构、长度可控的分子链，并详细研究了桥连配体和重复单元数对分子链整流效应的影响；2）构建了一对电子给体-桥-电子受体结构的分子链，研究了桥的共轭性对其电子传输性能的影响；3）将光敏单元组装到Rh2(RCOO)4单元骨架当中，制备了基于分子光电器件，并构建了宏观的光电探测器。