Physical and Photophysical Properties of Spin-Polarized Molecules

化学结构、动力学和机制B计划支持密歇根州立大学化学系的詹姆斯·K·麦卡斯克教授设计和开发化学系统，旨在确定分子的物理和/或光物理性质与其固有的自旋性质之间是否存在因果关系，如果存在，这种联系可以在多大程度上被利用来操纵分子系统的化学反应。在成功开发了第一个自旋控制偶极能量转移的实验模型的基础上，正在进行的具体项目是：(1)详细阐述该模型以确定其相对于Förster理论的适用范围，(2)将该模型扩展到交换能量转移(即，Dexter)，(3)零场自旋极化对自旋耦合过渡金属团簇中光诱导电子转移过程的影响，以及(4)自旋耦合金属半醌配合物分子的合成和表征，其中合成设计和理论被用于操纵分子内自旋极化。在所有这些项目中，这项研究是通过有机和无机合成化学、稳态和时间分辨光谱测量(包括(但不限于)发射、超快时间分辨吸收和电子顺磁共振)以及理论工作进行的，其中包括密度泛函理论计算，以探索将自旋和自旋极化结合到现有理论中来描述电子和能量转移动力学。支持这项研究的概念代表了关于分子光诱导性质的一个新的研究领域：这一项目将为了解一大类化合物的电子结构提供重要的见解，目前可用的实验信息很少。具有独特的自旋(电子的角动量)和/或磁性的化合物，特别是那些其性质可以以可预测的方式综合操纵的化合物，有望成为基于分子的电子材料的基础。通过这项工作所获得的知识可以为合理设计用于信息存储、能量转换和催化的下一代电子和光电子器件的分子体系提供基础。参与这项工作的个人，包括本科生和研究生的男性和女性，正在接受关于合成化学、最先进的光谱方法、分子体系磁性研究以及先进理论方法的广泛培训。

The Chemical Structure, Dynamics and Mechanisms B Program supports Professor James K. McCusker of the Department of Chemistry at Michigan State University for the design and development of chemical systems geared toward determining whether there exists a cause-and-effect relationship between the physical and/or photophysical properties of molecules and their innate spin properties, and if so, to what extent that connection can be exploited in order to manipulate the chemical reactivity of molecular systems. Building on the successful development of a model that led to the first experimental demonstration of spin control of dipolar energy transfer, specific projects being pursued are (1) elaboration of this model to determine the limits of its applicability with regard to Förster theory, (2) extension of this model to exchange energy transfer (i.e., Dexter), (3) the influence of zero-field spin polarization on photo-induced electron transfer processes in spin-coupled transition metal clusters, and (4) the synthesis and characterization of spin-coupled metal-semiquinone complexes molecules in which a combination of synthetic design and theory is being used to manipulate intramolecular spin polarization. In all of these projects, the research is being carried out through a confluence of organic and inorganic synthetic chemistries, steady-state and time-resolved spectroscopic measurements including (but not limited to) emission, ultrafast time-resolved absorption, and electron paramagnetic resonance, as well as theoretical efforts that include density functional theory calculations to explore the incorporation of spin and spin polarization into existing theories to describe electron and energy transfer dynamics.The concepts underpinning this research represent a new area of study concerning the light-induced properties of molecules: this project will provide important insights into an aspect of the electronic structure of an enormous class of compounds for which there is little experimental information presently available. Compounds possessing unique spin (angular momentum of electrons) and/or magnetic properties, particularly those whose properties can be manipulated synthetically in a predictable manner, hold promise as the basis for molecular-based electronic materials. The knowledge gained through this work can provide a foundation for the rational design of molecular systems for next-generation electronic and photo-electronic devices for information storage, energy conversion, and catalysis. The individuals involved in this work, which include men and women at both the undergraduate and graduate level, are receiving broad-based training in synthetic chemistry, state-of-the-art spectroscopic methodology, the study of the magnetic properties of molecular systems, as well as advanced theoretical methods.