We have studied aqueous solutions of native and chemically modified cyclodextrins
(CDs) by means of UV Raman and Brillouin scattering. Analysis of the
spectral profile of the OH‐stretching Raman signal, which is sensitive to the
intermolecular organization of water, reveals a remarkable reduction of the
population of ordered tetrahedral water structures inside the hydration shell
of substituted CDs. As a remarkable result, this destructuring effect seems to
be mainly related to the number of substituted hydroxyl groups in the CD ring
rather than to the chemical nature of the substituent group. UV Brillouin scattering
experiments confirm the structural picture emerging from the UV
Raman study, also providing an estimate of the activation energy associated
to the collective H‐bond restructuring mechanism in CD solutions. Overall,
the results provide a coherent description of the water–solute interactions in
aqueous solutions of CDs.
