15 - Modeling Primary Electron Transfer in Photosynthesis Using Supramolecular Structures

Abstract

This chapter focuses on modeling primary electron transfer in photosynthesis by using supramolecular structures. Biomimetic models for the study of photosynthetic electron transport are beginning to focus on electron transfer mediated by noncovalent interactions, such as hydrogen bonding, and on the role of the surrounding protein as a specialized solvent. This chapter reviews a number of covalently linked electron donor–acceptor systems that employ electron donors and acceptors that are closely analogous to the cofactors present in photosynthetic reaction centers. These systems are employed to study the dependence of electron transfer rates on the free energy of reaction, donor–acceptor distance and orientation, and solvents. Significant advances are being made to address problems associated with the environment surrounding a supramolecular species. The protein as a specialized solvent plays a significant role in determining both the rate and the energetics of electron transfer events. This role cannot be ignored in even the most sophisticated structures designed to promote long-lived charge separation. Future work in this field will focus more and more on solvation issues and on how one can understand the influence of the structure of adjacent molecules on electron donor–acceptor behavior.