Equilibrium Studies of Electron Transfer Reactions

The Ion Cyclotron Resonance (ICR) technique has been utilized extensively in recent years to measure equilibrium constants for ion-molecule reactions. In our laboratory at the University of California at Irvine, most of our effort has been focused on bimolecular proton transfer reactions. Equilibrium constants for positive ion-molecule reactions such as (1)$${H_3}{O^ + } + B = B{H^ + } + {H_2}O$$ provide a quantitative measure of the gas-phase basicity of the base B relative to water. Several hundred reactions of this type have been investigated for a wide variety of alcohols, amines, pyridines, esters and ethers [1,2]. Recently Michael Locke in our laboratory has measured the gas-phase basicity of several amino acids, purines, pyrimidines and nucleosides using a direct insertion probe to admit these low volatility compounds to the ICR analyzer cell [3,4].