We utilize electronic structure and molecular dynamics simulations to understand how solvents influence reaction thermodynamics and alter reaction pathways. Complementing traditional thermodynamic and structural analyses, we investigate solvation in terms of the sea of temporary and dynamic intermolecular interactions that dissolved molecules continuously respond to in solution.
The basis of Intermolecular Network Theory (and the algorithms in our ChemNetworks software) is to study patterns in liquid interactions using algorithms like Page Rank (utilized by the Google internet search engine) and the Dijkstra algorithm that forms the basis for the MapQuest routing algorithm, each of which can dissect short and long-range interactions that influence chemical reactivity in the solution phase.
Selected Research Projects
1) Synthesis and Performance of Nanoporous Materials for Separations.
Nanoporous materials, like metal organic frameworks (MOFs), can possess large surface areas with high porosity, and their physical properties can be tuned by appropriate selection of building blocks and/or post-synthetic modifications. One key challenge in the synthesis of MOFs is that the fundamental crystallization mechanism has yet to be fully understood. We have demonstrated that the use of co-solvents can tune the favorability of crystal formation in solution, helping to optimize solution-phase conditions for topological control and increased yield of MOFs . Once formed the organization of solvent inside a MOF or other nanoporous material can have a large impact upon its performance. In recent work we have demonstrated how different solvent respond to such confinement and how this is related to the ability of the material to separate solvents (e.g. in biofuel purification).
2) Solvent organization at liquid:liquid interfaces
The inability of one solvent to solvate another forms the basis of phase separation and an entire field dedicated toward using liquid:liquid interfaces to initiate chemical reactivity. We are particularly interested in metal-ligand complexation reactions at interfaces, as well as the transport of solutes across phase barriers. This has significant impact in the nuclear fuel cycle, where separation of fission products is an essential aspect of fuel recycling in the next generation of advanced nuclear fuel systems. Network analysis is helping to understand what the major features are of phase boundaries, how sensitive interfacial reactivity is to aqueous phase conditions, surface modifiers, and organic diluent conditions.
3) Solvent organization at solid:liquid interfaces
In a long term project we continue to examine solid:liquid interfaces and how toxic metals behave under environmentally relevant conditions and their reactivity at mineral surfaces.
4) Solvent mediated energy, proton, and electron transfer
In a recently funded project from the Department of Energy, with collaborators Christine Isborn (UC Merced) and Thomas Markland (Stanford), we are directly studying the effect of the solution environment on the excitation process of solutes related to photocatalysis and solar energy capture.