Fermi resonance as a tool for probing peridinin environment

Elizabeth Kish, Maria Manuela Mendes Pinto, Daniele Bovi, Marie Basire, Leonardo Guidoni, Rodolphe Vuilleumier, Bruno Robert, Riccardo Spezia, Alberto Mezzetti

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

In the present paper, we provide an extended study of the vibrational signature of a butenolide carotenoid, peridinin, in various solvents by combining resonance Raman spectroscopy (RRS) with theoretical calculations. The presence of a Fermi resonance due to coupling between the lactonic C-O stretching and the overtone of the wagging of the C-H in the lactonic ring provides a spectroscopic way of differentiating between peridinins lying in different environments. This is a significant achievement, given that simultaneous presence of several peridinins (each with a peculiar photophysical role) in different environments occurs in the most important peridinin containing proteins, the peridinin-chlorophyll proteins (PCPs) and the Chl a-c2-peridinin binding proteins. In RRS, small modifications of solvent polarity can give rise to large differences in the intensity and splitting between the two bands, resulting from the Fermi resonance. By changing the polarity, we can tune the frequency of stretching of the C-O and, while the C-H wagging frequency is almost always constant in different solvents, move the system from a perfect resonance condition to off-resonance ones. We have corroborated our spectroscopic findings with a quasi-classical dynamical model of two coupled oscillators, and DFT calculations on peridinin in different solvents; we have also used calculations to complete the peridinin vibrational mode assignments in the 800-1600 cm-1 region of RRS spectra, corresponding to polyene chain motion. Finally, the presence of Fermi resonance has been used to reinterpret previous vibrational spectroscopic experiments in PCPs.

Original languageEnglish
Pages (from-to)5873-5881
Number of pages9
JournalJournal of Physical Chemistry B
Volume118
Issue number22
DOIs
Publication statusPublished - 05 Jun 2014
Externally publishedYes

Fingerprint

Dive into the research topics of 'Fermi resonance as a tool for probing peridinin environment'. Together they form a unique fingerprint.

Cite this