7 research outputs found
Structure of the Sec13–Sec16 edge element, a template for assembly of the COPII vesicle coat
The crystal structure of a Sec13–Sec16 complex reveals its functions in the early steps of COPII coat complex assembly
Time-Resolved Infrared Studies of a Trimethylphosphine Model Derivative of [FeFe]-Hydrogenase
Model compounds that structurally
mimic the hydrogen-producing
active site of [FeFe]-hydrogenases have been studied to explore potential
ground-state electronic structure effects on reaction mechanisms compared
to hexacarbonyl derivatives. The time-dependent behavior of Fe<sub>2</sub>(μ-S<sub>2</sub>C<sub>3</sub>H<sub>6</sub>)(CO)<sub>4</sub>(PMe)<sub>2</sub> (<b>A</b>) in room temperature <i>n</i>-heptane and acetonitrile solutions was examined using
various ultrafast UV and visible excitation pulses with broadband
IR-probe spectroscopy of the carbonyl (CO) stretching region. Ground-
and excited-state electronic and CO-stretching mode vibrational properties
of the possible isomers of <b>A</b> were also examined using
density functional theory (DFT) computations. In <i>n</i>-heptane, 355 and 532 nm excitation resulted in short-lived (135
± 74 ps) bands assigned to excited-state, CO-loss photoproducts.
These bands decay away, forming new long-lived absorptions that are
likely a mixture of isomers of both three-CO and four-CO ground-state
isomers. These new bands grow in with a time scale of 214 ± 119
ps and persist for more than 100 ns. In acetonitrile, similar results
are seen with a 532 nm pump, but the 355 nm data lack evidence of
the longer-lived bands. In either solvent, the 266 nm pump data seem
to also lack longer-lived bands, but the intensities are significantly
lower in this data, making firm conclusions more difficult. We suggest
that these wavelength-dependent excitation dynamics significantly
alter potential mechanisms and efficiencies for light-driven catalysis