Tryptophol cation conformations studied with ZEKE spectroscopy.
Quanli Gu1, Swarna Basu, J L Knee
1Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459, USA.
The Journal of Physical Chemistry. A
|February 20, 2007
Summary
This study determined the relative energies of tryptophol cation conformations using zero kinetic energy photoelectron spectroscopy. Results show ionization significantly alters structure, driven by hydroxyl group interactions with the aromatic system.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Understanding molecular conformations and their energetic stability is crucial in chemistry.
- Tryptophol, a biologically relevant molecule, exists in multiple conformations.
- Previous studies established high-resolution electronic spectroscopy for neutral tryptophol conformers.
Purpose of the Study:
- To determine the relative energies of tryptophol cation conformations.
- To investigate structural changes upon ionization.
- To correlate electronic structure changes with molecular conformation.
Main Methods:
- Zero Kinetic Energy (ZEKE) photoelectron spectroscopy.
- Photoionization efficiency measurements.
- High-resolution electronic spectroscopy of neutral tryptophol.
- Quantum chemical calculations.
Main Results:
- Relative energies of several tryptophol cation conformations were determined.
- Adiabatic ionization energy for one specific conformation was definitively established.
- Two other conformer energies were estimated.
- Spectra and calculations revealed structural changes dominated by hydroxyl group interactions with the aromatic system.
Conclusions:
- ZEKE photoelectron spectroscopy successfully assigned and analyzed tryptophol cation conformations.
- Ionization induces significant structural rearrangements, particularly involving the hydroxyl group.
- This work provides a detailed understanding of tryptophol cation energetics and structure-property relationships.
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