Dynamics and Mechanisms of Electron Delocalization over Supramolecular Mixed Valence Systems

在这个由化学部化学结构、动力学和机制B项目资助的项目中，加州大学圣地亚哥分校（UCSD）化学和生物化学系的Clifford P. Kubiak教授将开发和研究能够进行超快化学反应的新系统，这些反应在万亿分之一秒（1皮秒）内发生在大型超分子结构上。本研究的目标是通过大型材料的自组装来开发具有与信息存储和开关相关的特定功能的分子器件。本项目将研究的超分子混合价络合物以及电子在它们之间转移的动力学研究，为组装能够形成、存储和转移电荷的复杂结构提供了一种化学驱动的方法。对这些系统的研究可能会影响和引导对特定化学、物理和工程问题的更广泛的思考，这些问题将使基于分子电子的设备成为主流，研究结果将被广泛传播。该项目将通过加州大学圣地亚哥分校本科生研究导师计划继续吸引本科生参与。该项目还将与加州大学圣地亚哥分校现有的外展项目相结合，以招收代表性不足的学生。还将与瑞典乌普萨拉大学的一个研究小组进行强有力的国际合作。通过非共价相互作用研究电子转移过程对于更广泛地理解自然和人工超分子系统中远程电子转移是如何发生的非常重要。这个项目建立在之前国家科学基金会支持期的发现之上。具体来说，它将涉及超分子混合价配合物中电子离域的动力学和机制的实验研究。合成研究的方向将是制备由弱非共价相互作用连接的新型超分子组装体，包括氢键和pi堆叠有机结构。这些将用于测试混合价系统中红外谱线形状与电子转移动力学机制之间关系的理论。研究超分子配合物中的超快电子转移，以确定电子注入超分子组装后的离域时间尺度和机制。该项目旨在探索复杂结构组装的新概念——利用电子离域来“强化”氢键等弱相互作用，以产生更稳定的组装，并将它们定位为更永久的化学附着形式。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Clifford P. Kubiak of the Department of Chemistry & Biochemistry at the University of California, San Diego (UCSD) will develop and study new systems that undergo ultrafast chemical reactions, those that occur in one-trillionth of a second (1 picosecond) over large supramolecular structures. The goal of this research is to develop molecular devices by the self-assembly of large materials with specific functions related to information storage and switching. The supramolecular mixed valence complexes that will be studied in this project and studies of the dynamics of electron transfer across them offer a chemistry-driven approach to assembling complex structures that can gate, store, and transfer charges. The study of these systems will likely influence and guide broader thought about the specific chemical, physical, and engineering issues that will bring molecular electronic based devices into the mainstream, and findings will be widely disseminated. The project will continue to involve undergraduate students through the UCSD undergraduate research mentor program. The project will also be interfaced with existing outreach programs at UCSD for the recruitment of underrepresented students. There will also be a strong international collaboration with a research group at the University of Uppsala, Sweden.The study of electron transfer processes through non-covalent interactions is important to the broader understanding of how long-range electron transfer occurs in natural and artificial supramolecular systems. This project builds on discoveries from the immediately preceding NSF support period. Specifically, it will involve experimental studies of the dynamics and mechanisms of electron delocalization in supramolecular mixed valence complexes. Synthetic studies will be directed toward the preparation of new supramolecular assemblies linked by weak non-covalent interactions including hydrogen bonds and pi-stacked organic structures. These will be used to test theories of the relationship between infrared spectral lineshape and the dynamical mechanism for electron transfer in mixed valent systems. Studies of ultrafast electron transfer in supramolecular complexes will be conducted to determine the timescale and mechanism of delocalization of an electron after its injection into a supramolecular assembly. This project seeks to explore a new concept in the assembly of complex structures - the use of electron delocalization to "harden" weak interactions like hydrogen bonds to produce more stable assemblies, and position them for more permanent forms of chemical attachment.