Structure/Function relationships in porous hybrid materials
Metal organic frameworks (MOFs) constitute a relatively new class of hybrid porous materials comprised of metal-containing inorganic clusters connected by organic linker groups. Their porous nature, ability to self-assemble and versatile chemical composition and structure makes them ideal for potential applications in gas separation and storage, luminescence-based sensing and heterogeneous catalysis. Most studies of MOF materials that focus on these functionalities give only cursory explanations of the electronic and structural properties behind them. In particular, a molecular level understanding of the interactions between the host framework and guest molecules contained within the pores is rarely known, yet is crucial for the rational design of MOF materials for their intended applications. In this work, both vibrational spectroscopy and X-ray characterization methods are being used to interrogate the molecular level host-guest interactions and local coordination environment around the metal sites in a series of MOF materials. These studies will afford new local structural and electronic information to better understand these materials and help facilitate the design of new frameworks with improved functionality.
Structural dynamics of transition metal charge-transfer complexes and electron donor-acceptor systems
Transition metal coordination complexes have attracted much attention for their photoinduced electron transfer reactions that make them useful for solar energy conversion and photocatalysis applications. To design systems with optimal charge transfer efficiencies, a comprehensive understanding of the excited state pathways is needed. The molecular structural changes that accompany photoinduced electron transfer are often the least understood part of the process. The goal of this project is to elucidate these structural dynamics in solar energy relevant complexes using resonance Raman and femtosecond pump-probe spectroscopy techniques. Specifically the low frequency intramolecular vibrational modes coupled to these electron transfer reactions will be interrogated. Systems of interest include e- donor-acceptors, mixed-valence, and interfacial electron transfer.