Toward High Intensity Forbidden EPR Transitions In Bimetallic Complexes

双金属配合物中高强度禁止的 EPR 转变

• 批准号: 2419767
• 负责人: Joseph Zadrozny
• 金额: $ 45万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2419767&HistoricalAwards=false
• 关键词: Toward; Intensity; Forbidden; EPR; Transitions

With support from the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Joseph Zadrozny of the Department of Chemistry at Colorado State University is developing new classes of dinuclear transition metal complexes to probe forbidden electron paramagnetic resonance (EPR) spectroscopic transitions. The goal of this research is to exploit the characteristics of these dinuclear species to understand how molecular structure can assist in violating EPR selection rules to enable high intensity transitions. The specific transitions being explored may yield new capabilities for bioimaging techniques that use EPR transitions. The research project spans the interface of inorganic and physical chemistries with synthetic and spectroscopic analyses as a key part of the work. The broader outreach goals for the program will be to create an easy-to-access lesson for synthetic chemists to approach the selection rules of EPR. This plan will follow the pedagogical strategies commonly employed for more common techniques, e.g. UV-vis spectroscopy, and as such aims to be a cornerstone in bringing new chemists into the EPR arena.The longer-term goal for the work is to enable low-frequency EPR transitions at high magnetic field, which would permit the chemical sensitivity of EPR imaging to be integrated with MRI. The singlet-to-triplet transition of two-spin systems is a promising way to realize such an EPR transition, because of its unique field dependence. Yet, the transition is forbidden and therefore weak hence, chemical design strategies for molecules to override the EPR selection rule and increase signal intensity are needed. Dinuclear metal complexes have a plethora of magnetic interactions that could potentially violate the EPR selection rule, but experimental tests of the efficacy of these violations have yet to be performed. This work will study the singlet-to-triplet transition in a variety of dinuclear metal complexes to explore how exchange coupling, hyperfine coupling, and relative spin orientation all contribute to the intensity of the forbidden resonance.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.

在化学系化学结构、动力学机制B项目的支持下，科罗拉多州立大学化学系的Joseph Zadrozny教授正在开发新的双核过渡金属配合物，以探测禁戒电子顺磁共振（EPR）光谱跃迁。 这项研究的目标是利用这些双核物种的特性，以了解分子结构如何有助于违反EPR选择规则，以实现高强度跃迁。正在探索的特定转换可能会产生新的能力，使用EPR转换的生物成像技术。该研究项目涵盖无机和物理化学的界面，合成和光谱分析是工作的关键部分。该计划更广泛的外展目标将是为合成化学家创建一个易于获取的课程，以接近EPR的选择规则。该计划将遵循更常见的技术，如紫外-可见光谱学，通常采用的教学策略，并因此旨在成为一个基石，使新的化学家进入EPR竞技场的工作的长期目标是使低频EPR跃迁在高磁场，这将允许EPR成像的化学灵敏度与MRI集成。双自旋体系的单重态到三重态的跃迁，由于其独特的场依赖性，是实现这种EPR跃迁的一种很有前途的方法。然而，这种跃迁是被禁止的，因此很弱，因此需要分子的化学设计策略来克服EPR选择规则并增加信号强度。双核金属配合物具有过多的磁相互作用，可能会违反EPR选择规则，但这些违规行为的有效性的实验测试尚未进行。这项工作将研究各种双核金属络合物中的单线态到三线态跃迁，以探索交换耦合、超精细耦合和相对自旋取向如何对禁戒共振的强度做出贡献。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。