Resolving the Impact of Hydrogen Bonding on the Phylloquinone Cofactor through Two-Dimensional Infrared Spectroscopy.

Two-dimensional infrared spectroscopy (2DIR) was applied to phylloquinone (PhQ), an important biological cofactor, to elucidate the impact of hydrogen bonding on the ultrafast dynamics and energetics of the carbonyl stretching modes. 2DIR measurements were performed on PhQ dissolved in hexanol, which served as the hydrogen bonding solvent, and hexane, which served as a non-hydrogen bonding control. Molecular dynamics simulations and quantum chemical calculations were performed to aid in spectral assignment and interpretation.

Three-Photon Spectroscopy of Porphyrins.

Recent advances in laser technology have made three-photon (3P) microscopy a real possibility, raising interest in the phenomenon of 3P absorption (3PA). Understanding 3PA of organic chromophores is especially important in view of those imaging applications that rely on exogenous probes, whose optical properties can be manipulated and optimized. Here, we present measurements and theoretical analysis of the degenerate 3PA spectra of several phosphorescent metalloporphyrins, which are used in the construction of biological oxygen probes.

Unraveling Confined Dynamics of Guests Trapped in Self-Assembled PdL Nanocages by Ultrafast Mid-IR Polarization-Dependent Spectroscopy.

Self-assembled coordination cages form host-guest complexes through weak noncovalent interactions. Knowledge of how these weak interactions affect the structure, reactivity, and dynamics of guest molecules is important to further the design principles of current systems and optimize their specific functions. We apply ultrafast mid-IR polarization-dependent pump-probe spectroscopy to probe the effects of two PdL self-assembled nanocages on the properties and dynamics of fluxional group-VIII metal carbonyl guest molecules.