Mechanistic aspects of dipole-mediated intramolecular electron transfer: Study of the photoinduced dynamics of charge hopping in anthranilamide structures

在这个由化学系化学结构、动态和机制B项目资助的项目中，加州大学河滨分校生物工程系、化学系和生物化学系以及材料科学与工程专业的Val Vullev教授将开发一类具有强偶极子的仿生驻极体（驻极体是磁铁的电类似物），并研究它们如何介导电荷转移。这项研究有可能提高太阳能电池、能量存储设备和有机电子产品的性能。本项目处于物理有机化学和生物启发分子工程的界面。因此，它为推广、招聘、教育和留住对科学和工程有广泛兴趣的不同学生群体提供了坚实的基础。该项目还有一个面向目前在科学和工程领域代表性不足的学生的外联部分。大多数研究电荷转移（CT）动力学对偶极子取向的依赖使用蛋白质螺旋。然而，这种蛋白质结构通过电子隧道介导CT，这限制了有效CT的距离。这个项目的重点是一类新的偶极分子结构，基于蒽酰胺，类似于蛋白质螺旋，有有序的酰胺和氢键，导致大的电偶极矩。然而，与蛋白质不同的是，anthanilamide沿着其骨干延伸了pi-偶联，这有望为远程CT提供途径。在本项目中，将开发各种各样的蒽酰胺分子驻极体，以回答以下问题：1)通过将CT机制从隧穿调整到跳变，是否可以显着延长电荷转移范围？2)将隧穿机制转变为跳变机制对正向电荷迁移和非期望电荷重组的CT整流有何影响？3)偶极子产生的电场如何影响沿CT路径的电荷捕获？

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Val Vullev of the Departments of Bioengineering, Chemistry, and Biochemistry, and of the Materials Science and Engineering Program at the University of California, Riverside will develop a class of bio-inspired electrets with strong dipoles (electrets are the electric analogues of magnets) and study how they mediate charge transfer. The research could potentially improve the performance of solar cells, energy-storage devices and organic electronics. This project lies at the interface of physical organic chemistry and bio-inspired molecular engineering. Therefore, it provides a solid foundation for outreach, recruitment, education and retention of diverse cohorts of students with a wide range of interests in science and engineering. The project also has an outreach component directed at students currently underrepresented in science and engineering. The majority of studies investigating the dependence of charge-transfer (CT) kinetics on the orientation of dipoles use protein helices. Such protein structures, however, mediate CT via electron tunneling, which limits the distance of efficient CT. This project focuses on a new class of dipolar molecular structures, based on anthranilamides, that similar to protein helices have ordered amide and hydrogen bonds resulting in large electric dipole moments. Unlike proteins, however, the anthranilamides have extended pi-conjugation along their backbones, which is expected to provide pathways for long-range CT. In this project, a diverse range of anthranilamide molecular electrets will be developed to answer the following questions: 1) By tuning the CT mechanism from tunneling to hopping, can the range of charge transfer be significantly extended? 2) How will changing the mechanism from tunneling to hopping affect CT rectification of forward charge migration and the undesired charge recombination? 3) How the dipole-generated fields affect charge trapping along CT pathways?