Photoisomerization: New Complexes, Circular Dichroism, and the Faraday Effect

当暴露在光下时发生颜色变化的络合物称为光致变色。这些类型的化合物在不同的环境中有不同的应用，包括计算和光子材料。这项研究计划致力于了解这些光致变色化合物(最终是材料)如何与光相互作用产生颜色变化。大多数已知的光致变色化合物通过发生在超快时间尺度(皮秒)上的光触发的分子重排来运作。关于分子如何将光能转化为势能以引发分子重排，还有许多悬而未决的问题。这项研究计划的一个新方面是开发新的光学实验技术，以在很短的时间尺度上监测分子的结构和磁性变化。新墨西哥大学的Jeffrey Rack教授正致力于一系列外展工作，以鼓励学生在STEM学科中追求职业生涯。他对支持美国原住民学生、西班牙裔学生和女性的职业发展特别感兴趣。该项目提供了设计仪器的经验，以解决化学和物理之间的接口问题。该项目的多学科性质要求学生研究人员了解不同研究领域的文献贡献。NSF化学系化学结构、动力学和机理B项目的这项研究奖支持新墨西哥大学的Jeffrey Rack教授的研究工作，他研究了一类新的过渡金属络合物，当暴露在太阳辐射(光)下时，这些络合物会改变结构和颜色。这些研究的重点是发现这一独特的发色团家族的动力学和热力学参数，这些发色团利用光在非常快的时间尺度上断裂和成键。这些络合物中的作用方式是结合的亚砜配体的激发态异构化。此外，还介绍了两种新的乐器技术。首先，Rack教授正在研究时间分辨圆二色谱的发展，以监测手性变化，不仅在过渡金属亚砜络合物中，而且在手性亚砜化合物中。其次，瑞克教授正在开发一种法拉第旋转光谱仪器，它可以监测化合物和材料中的磁场。这项技术被用来监测分子光物理中三重态的产生和命运。新墨西哥大学的Jeffrey Rack教授致力于一系列推广工作，鼓励学生在STEM学科中追求职业生涯，并对支持美国原住民学生、西班牙裔学生和女性的职业发展特别感兴趣。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Complexes that undergo a change in color when exposed to light are termed photochromic. These types of compounds have a variety of applications in diverse settings including computing and photonic materials. This research program is dedicated to understanding how these photochromic compounds (and ultimately materials) interact with light to generate color changes. Most of the known photochromic compounds operate through a light-triggered molecular rearrangement that occurs on an ultrafast timescale (picosecond). There are many unanswered questions regarding how molecules convert light energy into potential energy to initiate molecular rearrangement. A new aspect of this research program is the development of new optical experimental techniques to monitor structural and magnetic changes in molecules on very short timescales. Professor Jeffrey Rack at the University of New Mexico is engaged in a series of outreach efforts to encourage students to pursue careers in STEM disciplines. He has a particular interest in supporting Native American students, Hispanic students, and women in their career development. The project provides experience in the design of instrumentation to address questions at the interface between chemistry and physics. The multidisciplinary nature of the project demand that the student researchers be aware of literature contributions in disparate research areas.This research award in the Chemical Structure, Dynamics and Mechanisms B Program within the Division of Chemistry at NSF supports the research efforts of Professor Jeffrey Rack at University of New Mexico to investigate a new class of transition metal complexes which change structure and color when exposed to solar radiation (light). These studies focus on discovering the kinetic and thermodynamic parameters for the action of this unique family of chromophores that utilize light to break and make bonds on a very fast timescale. The mode of action in these complexes is an excited state isomerization of the bound sulfoxide ligand. In addition, two new instrumental techniques are introduced. First, Professor Rack is studying the development of a time-resolved circular dichroism to monitor chirality changes, not only in transition metal sulfoxide complexes, but also in chiral sulfoxide compounds. Second, Professor Rack is developing a Faraday rotation spectroscopic instrument, which monitors magnetic fields in compounds and materials. This technique is used to monitor the creation and fate of triplet states in molecular photophysics. Professor Jeffrey Rack at the University of New Mexico is engaged in a series of outreach efforts to encourage students to pursue careers in STEM disciplines, and has a particular interest in supporting Native American students, Hispanic students, and women in their career development.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.