Vibrational Sum-Frequency Generation Activity of a 2,4-Dinitrophenyl Phospholipid Hybrid Bilayer: Retrieving Orientational Parameters from a DFT Analysis of Experimental Data

D. Lis, J. Guthmuller, B. Champagne, C. Humbert, B. Busson, A. Peremans, F. Cecchet

Résultats de recherche: Contribution à un journal/une revueArticle

Résumé

The vibrational nonlinear activity of films of 2,4-dinitrophenyl phospholipid (DNP) at the solid interface is measured by sum-frequency generation spectroscopy (SFG). Hybrid bilayers are formed by a Langmuir-Schaefer approach in which the lipid layer is physisorbed on top of a self-assembled monolayer of dodecanethiol on Pt with the polar heads pointing out from the surface. The SFG response is investigated in two vibrational frequency domains, namely, 3050-2750 and 1375-1240 cm. The first region probes the CH stretching modes of DNP films, and the latter explores the vibrational nonlinear activity of the 2,4-dinitroaniline moiety of the polar head of the lipid. Analysis of the CH stretching vibrations suggests substantial conformational order of the aliphatic chains with only a few gauche defects. To reliably assign the detected SFG signals to specific molecular vibrations, DFT calculations of the IR and Raman activities of molecular models are performed and compared to experimental solid-state spectra. This allows unambiguous assignment of the observed SFG vibrations to molecular modes localized on the 2,4-dinitroaniline moiety of the polar head of DNP. Then, SFG spectra of DNP in the 1375-1240 cm frequency range are simulated and compared with experimental ones, and thus the 1,4-axis of the 2,4-dinitrophenyl head is estimated to have tilt and rotation angles of 45±5° and 0±30°, respectively. Nonlinear vibrational response of a hybrid bilayer of 2,4-dinitrophenyl phospholipid (DNP) supported on a Pt surface is interpreted qualitatively and quantitatively by sum-frequency generation spectroscopy and density functional theory calculations. Spectral simulations also reveal the orientation of the 2,4-dinitrophenyl polar head of DNP, which is estimated to have tilt and rotation angles of 45±5° and 0±30°, respectively (see picture).
langue originaleAnglais
Pages (de - à)1227-1236
Nombre de pages10
journalChemPhysChem
Volume14
Numéro de publication6
Date de mise en ligne précoce3 avr. 2013
Les DOIs
Etat de la publicationPublié - 15 avr. 2013

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    • 2 Participation à une conférence, un congrès

    Biointerfaces Symposium

    Francesca Cecchet (Orateur invité)

    12 mai 2015

    Activité: Types de Participation ou d'organisation d'un événementParticipation à une conférence, un congrès

    Action Nationale de Formation du CNRS en "Spectroscopie et Imagerie d’interfaces materiaux- molecules du vivant"

    Francesca Cecchet (Orateur invité)

    15 oct. 201417 oct. 2014

    Activité: Types de Participation ou d'organisation d'un événementParticipation à une conférence, un congrès

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