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Vibrational characterization of L ‐valine phosphonate dipeptides: FT‐IR, FT‐RS, and SERS spectroscopy studies and DFT calculations
Author(s) -
PodstawkaProniewicz Edyta,
Andrzejak Marcin,
Kafarski Paweł,
Kim Younkyoo,
Proniewicz Leonard M.
Publication year - 2011
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2821
Subject(s) - chemistry , amide , fourier transform infrared spectroscopy , raman spectroscopy , molecule , phosphonate , substrate (aquarium) , crystallography , stereochemistry , infrared spectroscopy , organic chemistry , physics , oceanography , quantum mechanics , optics , geology
Four L ‐valine ( L ‐Val) phosphonate dipeptides that are potent inhibitors of zinc metalloproteases, namely, L ‐Val‐C(Me) 2 ‐PO 3 H 2 (V1), L ‐Val‐CH(iP)‐PO 3 H 2 (V2), L ‐Val‐CH(iB)‐PO 3 H 2 (V3), and L ‐Val‐C(Me)(iP)‐PO 3 H 2 (V4), are studied by Fourier‐transform infrared (FT‐IR) spectroscopy, Fourier‐transform Raman spectroscopy (FT‐RS), and surface‐enhanced Raman scattering (SERS). The band assignment (wavenumbers and intensities) is made based on (B3LYP/6‐311 + + G**) calculations. Comparison of theoretical FT‐IR and FT‐RS spectra with those of SERS allows to obtain information on the orientation of these dipeptides as well as specific‐competitive interactions of their functionalities with the silver substrate. More specifically, V1 and V4 appear to interact with the silver substrate mainly via a C sg CH 3 moiety localized at the N amide C sg (CH 3 )Pmolecular fragment. In addition, the POH and isopropyl units of V4 assist in the adsorption process of this molecule. In contrast, the C α NH 2 and PO 3 H − groups of V2 and V3 interact with the silver nanoparticles, whereas their isopropyl and isobutyl fragments seem to be repelled by the silver substrate (except for the CH 2 of V3), similar to the C β (CH 3 ) 2 fragment of L ‐Val for all L ‐Val phosphonate dipeptides investigated in this work. The adsorption mechanism of these molecules onto the colloidal silver surface is also affected by amide bond behavior. Copyright © 2010 John Wiley & Sons, Ltd.