PHYS 329-Applications of ultrafast 2-D infrared spectroscopy to studies of the Fe-hydrogenase enzyme system

Ultrafast two dimensional infrared spectroscopy has been applied to study the structure and vibrational dynamics of model compounds of the active site of the Fe-hydrogenase enzyme system. 1 Studies of these model systems, which allow separation of the active site of the enzyme from the protein scaffolding allow, by comparison of 2D-IR spectra with density functional theory calculations, determination of the solution phase structure of these species. In addition, vibrational coupling and rapid (<5ps), solvent-mediated equilibration of energy between vibrationally-excited states of the carbonyl ligands of the di-iron-based active site is observed prior to relaxation to the ground state. These dynamics are shown to be solvent-dependent and form a basis for determination of the vibrational interactions between active site and protein.
The results of two-colour 2D-IR and 2D-IR studies of transient products of a photo-substitution reaction are also presented, which give new insights into vibrational energy relaxation mechanisms in similar, solution-phase metal-carbonyl systems.