Probing the structures and interactions in reactive complexes and ionic clusters

Understanding inter- and intramolecular interactions provide direct insights on molecular structure and reactivity.  As such, it is vitally important in many research areas, such as developments in rational design of catalysts and molecular recognition.  Utilizing a method based upon a unique combination of mass spectrometry and laser spectroscopy, our research focuses on capturing and characterizing complexes of interest to provide a molecular-level detailed examination of their structures and interactions.  To capture and isolate reaction intermediates, we take advantage of the high sensitivity and selectivity afforded by mass spectrometry.  To access otherwise unstable and short-lived species as well as microsolvated complexes, we developed new capabilities to perform temperature-controlled gas-phase chemistry and clustering.  These carefully isolated and prepared complexes are directly probed inside the mass spectrometer using infrared predissociation spectroscopy, yielding well-resolved spectra that contain a wealth of information.  In this talk, I will present the application of our unique methodology in studies of model systems as well as homogeneous catalytic water oxidation driven by the [Ru(tpy)(bpy)(H₂O)]²⁺ complex.  We successfully characterized several intermediates along the catalytic cycle as well as the solvent rearrangement in the first proton-coupled oxidation step.  Recent characterization of solvent effects on the structure of flexible peptides will also be discussed, highlighting the challenges encountered while probing increasingly complex molecules and clusters.