8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Tue 611:23-14:00P2.69Temperature and concentration effect on the hydrationproperties of cyclodextrin and its substituted form: adepolarized light scattering studyBarbara Rossi, 1 Lucia Comez, 2 Laura Lupi, 3 Daniele Fioretto, 3 Silvia Caponi, 2 andFlavio Rossi 11 University of Trento, via Sommarive 14, Povo, 38123, Trento, Italy2 IOM/CNR, Perugia, Italy3 University of Perugia, Perugia, ItalyCyclodextrins (CD) are cyclic oligosaccharides formed by 6-8 glucose units linked by 1, 4-alphaglicosidicbonds having a truncated cone structure, in which the arrangement of the functionalgroups of the glucose molecules is such to provide an internal hydrophobic (lipophilic) cavity anda hydrophilic outer surface, well-known for exhibiting inclusion-complex formation with a varietyof organic molecules, thereby altering the chemical-physical properties of the latter. Thanks tothese properties, CD are ideal candidates for development of new drug carriers due to their abilityto increase the speed of dissolving, solubility and stability of drugs and, currently, pharmaceuticalapplications of CD are widespread [1]. In this framework, understanding the role played bywater in activating the CD as host systems, such as the dynamics of the water in the surroundinghydration layers of these macrocycles, is a topic of considerably importance for developing newbased CDs materials with more efficient and versatile inclusion/release properties. Here we usebroad band depolarized light scattering experiments [2] performed on water solutions of differenttype of CD, in order to investigate the relaxation dynamics of the bulk and hydration water, in thepicosecond timescale, in turn related to the continuous mechanism of breaking and re-formingof hydrogen bonding, also in agreement with molecular dynamics simulations [3]. In particular,we follow the effects of (i) temperature, (ii) solute concentration and (iii) type of CD on thedepolarized light scattering spectra, in order to extract structural and dynamical information onthe solvent molecules in the surrounding hydration layers, in term of number of water moleculesand average hydrogen bond lifetime.[1] S. Li, W. C. Purdy Chem. Rev. 92, 1457 (1992).[2] B. Rossi et al. J. Raman Spectrosc. (2011) DOI: 10. 1002/jrs. 2885[3] M. Jana, S. Bandyopadhyay, Langmuir 25, 13084 (2009).69