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Issue 43, 2015
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Mode-specific fragmentation of amino acid-containing clusters

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A combination of infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations have been employed to study the structures and mode-specific dissociation pathways of the proton-bound dimer of 3-trifluoromethylphenylalanine (3-CF3-Phe) and trimethylamine (TMA). Three structural motifs are identified: canonical (charge-solvated), zwitterionic (charge-separated), and TMA-bridged. In the 1000–1350 cm−1 region, similar spectra are observed in the TMA·H+ and 3-CF3-Phe·H+ product channels. At wavenumbers above 1350 cm−1, infrared excitation of charge-solvated structures leads exclusively to production of protonated TMA, while excitation of zwitterionic or TMA-bridged structures results exclusively in production of protonated 3-CF3-Phe. The cluster potential energy landscape is topologically mapped and mechanisms for isomerization and mode-selective dissociation are proposed. In particular, cluster transparency as a result of IR-induced isomerization is implicated in deactivation of some IRMPD channels.

Graphical abstract: Mode-specific fragmentation of amino acid-containing clusters

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The article was received on 17 Jun 2015, accepted on 24 Aug 2015 and first published on 26 Aug 2015

Article type: Paper
DOI: 10.1039/C5CP03517A
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Phys. Chem. Chem. Phys., 2015,17, 28548-28555

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    Mode-specific fragmentation of amino acid-containing clusters

    W. Scott Hopkins, R. A. Marta, V. Steinmetz and T. B. McMahon, Phys. Chem. Chem. Phys., 2015, 17, 28548
    DOI: 10.1039/C5CP03517A

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