Weak Electronic Couplings in Biradicals and Radical Pairs: Through-Bond, Through-Space, and Through-Solvent

研究了双基态在不同环境下的电子自旋共振耦合。时间分辨电子顺磁共振将用于研究取代基、几何约束、距离、溶剂和温度对柔性有机双基的影响。研究中包括的介质包括有机溶剂、超临界流体、囊泡、胶束、液晶、聚合物和沸石。耦合常数的大小将提供关于弱耦合系统中通过溶剂与通过键相互作用的关键信息。在聚合物体系的情况下，聚合物链中双基位点的战略性放置将允许在聚合物的末端和中心探测旋转屏障。此外，将合成和研究含有临界浓度酮的聚合物，以确定下一代光降解大分子材料开发中的重要参数。这项来自有机动力学计划的资助，支持北卡罗来纳大学教堂山分校的马尔科姆·福布斯教授对化学系统中二元相互作用的研究。理解分子系统的不同部分通过电子方式相互通信的方法是至关重要的，以便能够在分子装置的背景下设计能够执行特定功能的分子。此外，双自由基研究的结果将指导具有光降解塑料潜力的新材料的合成。此外，光化学反应性聚合物将被设计用于增加传统上不相互作用的聚合物材料之间的附着力。

An investigation of electron spin resonance couplings of biradical species in a variety of different environments will be conducted. Time-resolved electron paramagnetic resonance will be used to study the effects of substituents, geometrical constraints, distance, solvent, and temperature between the flexible organic biradicals. Media to be included in the investigation include organic solvents, super critical fluids, vesicles, micelles, liquid crystals, polymers, and zeolites. The magnitude of the size of the coupling constants will provide critical information with respect to through solvent versus through bond interactions in weakly coupled systems. In the case of the polymer systems, strategic placement of the biradical sites in the polymer chain will allow rotational barriers to be probed both at the end and at the center of the polymer. In addition, polymers containing critical concentrations of ketones will be synthesized and investigated to define the parameters important in development of the next generation of photodegradable macromolecular materials. %%% This grant from the Organic Dynamics Program supports the investigation of biradical interactions in chemical systems by Professor Malcolm Forbes at the University of North Carolina at Chapel Hill. It is critical to understand the method by which different parts of molecular systems communicate with each other electronically in order to be in a position to design molecules that are capable of performing specific functions in the context of a molecular device. In addition, the synthesis of new materials with potential use as photodegradable plastics will be guided by the results of the biradical studies. Also photochemically reactive polymers will be designed to increase the adhesion between traditionally non-interactive polymeric materials.