CAS: Mechanistic Studies on How to Maximize Dipole Effects on Charge Transfer

在化学系化学结构、动力学和机制B项目的支持下，加州大学河滨分校生物工程、化学和生物化学系的Valentine Vullev教授正在开发新的方法，以提高所需电荷转移过程的效率，同时抑制不希望导致的电荷转移过程，例如，太阳能转换设备和材料的损失。电荷转移过程不仅对维持地球上的生命至关重要，而且对许多现代技术（如太阳能捕获）也至关重要。电偶极子本质上影响电荷转移。偶极子无处不在的性质，因此，需要深入了解它们对电荷转移的影响。Vullev教授的团队将开发光学方法来探测和绘制偶极子周围的局部纳米级电场。这些知识将使Vullev团队能够量化电荷转移中的偶极子效应，并制定出从这种效应中获益的方法。该项目处于有机化学和生物分子工程的交叉领域，有望为研究团队成员提供有价值的跨学科培训。Vullev研究小组积极开展涉及K-12学生的外展活动，并希望包括那些在科学方面得不到充分服务的群体的学生。该项目有两个目标：(1)开发光谱方法，利用电致变色，即光学斯塔克效应，探测和定位分子偶极子。这一知识将允许实验量化电子给体和电子受体的势受偶极子产生的场影响的程度；(2)研究偶极子大小和取向对电荷转移动力学的影响。该项目试图解决的一个关键未决问题是，在与重组能量相关的不同热力学驱动力的过程中，偶极子效应对电荷转移变化率的影响程度。由不同的蒽酰胺残基组成的仿生分子驻极体（具有有序电偶极子的系统）是本项目设计研究的系统的关键结构基序。从长远来看，该项目旨在建立重要的结构-功能关系，以优化感兴趣的电荷转移过程，使分子工程师能够在系统设计中抑制不希望发生的事件，如电荷重组。如果成功，这个研究项目的结果可能会影响广泛的科学领域，包括能量转换、生物能量学、分子和有机电子学。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。

With support from the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Valentine Vullev of the Departments of Bioengineering, Chemistry and Biochemistry at the University of California, Riverside, is developing new ways for improving the efficiency of desired charge-transferring processes while suppressing the undesired ones that lead, for example, to losses in solar-energy-conversion devices and materials. Charge transfer processes are essential, not only for sustaining life on Earth, but also for many modern technologies such as solar energy capture. Electric dipoles inherently affect charge transfer. The ubiquitous nature of dipoles, therefore, warrants deep understanding of their effects on charge transfer. Professor Vullev's group will develop optical approaches for probing and mapping the localized nanometer-scale electric fields around dipoles. Such knowledge would allow the Vullev team to quantify the dipole effects on charge transfer and to map out ways to benefit from such effects. The project lies at the interface of organic chemistry and bio-inspired molecular engineering, and is expected to provide research team member with valuable interdisciplinary training. The Vullev research group is active in outreach activities involving K-12 students, and aspires to include students from groups that have been underserved in science. This project has two objectives: (1) to develop spectroscopic approaches, using electrochromism, i.e., optical Stark effects, for probing and mapping molecular dipoles. This knowledge will allow experimental quantification of the extent to which the potentials of the electron donors and the acceptors are affected by the dipole-generated fields; (2) to study how dipole magnitude and orientation influence charge-transfer kinetics. A key pending question that this project seeks to address is the extent to which dipole effects on the rates of charge transfer change for processes with different thermodynamic driving forces, in relevance to the reorganization energy. Bio-inspired molecular electrets (systems with ordered electric dipoles) composed of different anthranilamide residues are the key structural motif for the systems designed for study in this project. In the long term, this project aims to establish important structure-function relationships for optimizing charge transfer processes of interest, allowing the molecular engineer to suppress undesired events, such as charge recombination, in the design of the system. If successful, the results this research project could impact a broad range of scientific areas, including energy conversion, bioenergetics, molecular and organic electronics.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.