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

University Of California-Riverside, Riverside CA

Investigators

Abstract

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?