Chapter 4: Isotope Effects as Analytical Probes: Applications of Computational Theory

We present an overview of the theory behind isotope effects, explaining how to predict them using modern computational techniques, and how the knowledge coming from computations can be used in the analysis of the behavior of various systems ranging from chemical to enzymatic processes. We illustrate current applications of theoretically predicted kinetic isotope effects using the example of oxidation and hydrogen abstraction reactions taking place in aqueous solution. We demonstrate the use of different computational QM/MM protocols in studies of enzymatic reactions such as dehalogenation, oxygenation, and hydroxylation. Finally, we discuss our ability to predict equilibrium isotope effects, such as vapor pressure isotope effects, using the example of the evaporation of pure-phase organic solvents, binding isotope effects, and isotope effects on the adsorption on graphene.