Phylloquinone (PhQ) plays a vital role in the electron transfer chain of oxygenic photosynthesis. When embedded in the protein environment, the properties of PhQ can be altered due to non-covalent interactions. In order to obtain a more fundamental understanding of the impacts of different non-covalent interactions on PhQ, we performed polarization-dependent two-dimensional infrared spectroscopy (2DIR) on PhQ in different solvents. From the 2DIR spectra, we map out changes to the ground state potential energy surface via the anharmonicity. By analyzing the time-resolved 2DIR data, we extract the effect of different solvation environments on the ultrafast dynamics of phylloquinone, measuring the vibrational lifetime of the carbonyl modes and calculating the degree of coupling between different modes. Cross peak analysis shows biexponential kinetics arising from ultrafast intramolecular vibrational energy redistribution between the carbonyl and the ring modes. We construct the anisotropy decay from polarization dependent measurements, finding it to be constant over the course of the vibrational lifetime. From the anisotropy of the 1 to 2 transitions and combination band signals, we calculate the orientations of the transition dipoles relative to the fundamental transition.<br/>

Ultrafast dynamics and orientational information extracted from phylloquinone with two-dimensional infrared spectroscopy

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.