Spin Effects on the Excited-state Dynamics of Transition Metal Complexes

在这个由化学部门化学结构、动力学和机制B项目资助的项目中，密歇根州立大学化学系的James K. McCusker教授将探索过渡金属基配合物的电子结构的某些方面如何在其光诱导化学性质中表现出来。正在研究的具体方面是电子自旋，它是人们广泛熟悉的许多性质（例如磁性）的起源，但其对光化学反应性的影响尚未阐明。为了实现这一目标，研究计划将涉及一系列化学系统的合成和表征，这些化学系统被设计成能够建立系统的自旋特性和光诱导特性之间的明确相关性。在合成有机和无机以及实验物理化学的界面工作，该研究将为学生提供一个肥沃的训练基地，以理解和欣赏这些形式上不同的化学子领域之间的相互联系，同时发展基本的新见解，了解原子结构的一个非常基本的组成部分如何被利用来创造新的分子功能，用于各种潜在的光使能应用。角动量守恒是自然界的一个基本性质。虽然它对分子科学的某些方面的影响是众所周知的，但这个研究项目正在提出以下问题：这个概念在光诱导的化学过程中体现到什么程度？为了解决这个基本问题，研究将涉及合成一系列过渡金属基供体-受体配合物，其自旋性质可以系统地改变，要么通过明智地选择单个金属离子（例如，用Co（III）取代Cr(III)），要么通过利用与海森堡交换耦合多核金属簇的自旋梯相关的温度依赖性。光诱导电子和/或能量转移动力学的表征将集中在稳态和时间分辨光谱上，包括变温超快光学和x射线方法。预计该研究将深入了解零场自旋极化如何在分子系统的光物理中表现出来，目的是证明考虑这些效应如何为使用自旋作为创建和操纵光诱导分子功能的设计特征的组合平台的开发提供新方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project, funded by the Chemical Structure, Dynamics and Mechanisms B Program of the Chemistry Division, Professor James K. McCusker of the Department of Chemistry at Michigan State University will be exploring how certain aspects of the electronic structure of transition metal-based complexes manifest in their photo-induced chemical properties. The specific aspect being studied is electron spin, which is the origin of many properties that people are widely familiar with (e.g., magnetism) but whose influence on photochemical reactivity has not been elucidated. To achieve this goal, the research program will involve the synthesis and characterization of a range of chemical systems that have been designed to enable the establishment of a clear correlation between the spin properties of the system and the photo-induced properties that they exhibit. Working at the interface of synthetic organic and inorganic and experimental physical chemistry, the research will provide a fertile training ground for students to understand and appreciate the interconnection between these formally disparate subfields of chemistry while developing fundamental new insights into how a very basic component of atomic structure can be leveraged to create new molecular functionality for a wide variety of potential light-enabled applications.Conservation of angular momentum is a fundamental property of Nature. While its influence on certain aspects of molecular science are well known, this research program is asking the following: to what extent does this concept manifest in photo-induced chemical processes? To address this fundamental question, the research will involve the synthesis of a series of transition metal-based donor-acceptor complexes whose spin properties can be systematically varied, either by judicious choice of a single metal ion (e.g., replacement of Cr(III) by Co(III)) or by exploiting the temperature dependence associated with the spin ladder of a Heisenberg exchange-coupled polynuclear metal cluster. Characterization of the photo-induced electron and/or energy transfer dynamics will focus on steady-state and time-resolved spectroscopies, including variable-temperature ultrafast optical and x-ray methods. It is anticipated that the research will provide insight into how zero-field spin polarization manifests in the photophysics of molecular systems with the goal of demonstrating how consideration of these effects can suggest new approaches for the development of compositional platforms using spin as a design feature for creating and manipulating photo-induced molecular functionality.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.