Mobility of Intermediates in Highly Channeled Reaction Cascades

Abstract

Novel and energy systems and synthetic processes can benefit from multistep chemical cascades, which allow combination of multiple reaction in a single overall process. Such cascades are ubiquitous in nature, and have been applied to of biosensors and biofuel cell designs as well. But, the efficiency of cascade reactions is significantly limited by the transport of intermediates. Intermediate channeling phenomenon is found to be one of the solutions to this problem in nature, and can include confinement, electrostatic interactions, and other mechanisms. Here we describe the quantitative tools we have developed to describe these channelling systems quantitatively, and to interrogate them experimentally. We specifically apply analysis techniques for infrequent events such as occur with tightly bonded intermediates to probe the tradeoff between retention of intermediates near or within catalytic complexes, and the reduction of mobility such retention entails. We show that because of the very short time scales of transport as compared to reaction, strong retention of intermediates is advantageous even if such retention dramatically reduces intermediate mobility.