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Cirtog M.,French Atomic Energy Commission | Cirtog M.,INC and INP | Cirtog M.,Radboud University Nijmegen | Rijs A.M.,INC and INP | And 12 more authors.
Journal of Physical Chemistry Letters | Year: 2012

Far/mid-IR signatures of the first hydration step of a flexible biomolecule, the model peptide chain Ac-Phe-NH2, have been investigated in the gas phase using the selective IR/UV double-resonance laser technique. The broad spectral region investigated with the free-electron laser FELIX (150-800 cm-1/70-12 μm) provided a direct access to three intermolecular vibrational modes of monohydrates, in which the water molecule bridges neighboring NH and CO sites of the peptide backbone. The spectral features, analyzed with the help of quantum chemistry, are assigned to the IR activity of the libration and wagging motions of the water molecule together with a strongly mode- and conformer-dependent vibrational coupling between solute and solvent molecules. These resolved spectra obtained in a so far poorly documented spectral region provide benchmark data, which should enable theoreticians of molecular interactions to assess their methods, in terms of both intermolecular potentials and treatment of the vibrational anharmonicity. © 2012 American Chemical Society.

Gloaguen E.,INC and INP | Gloaguen E.,CEA Saclay Nuclear Research Center | Mons M.,INC and INP | Mons M.,CEA Saclay Nuclear Research Center
Topics in Current Chemistry | Year: 2014

This chapter examines the structural characterisation of isolated neutral amino-acids and peptides. After a presentation of the experimental and theoretical state-of-the-art in the field, a review of the major structures and shaping interactions is presented. Special focus is made on conformationally-resolved studies which enable one to go beyond simple structural characterisation; probing flexibility and excited-state photophysics are given as examples of promising future directions. © Springer International Publishing Switzerland 2014.

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