%0 Journal Article
%A Eguchi, Kazuya
%A Niether, Doreen
%A Wiegand, Simone
%A Kita, Rio
%T Thermophoresis of cyclic oligosaccharides in polar solvents
%J The European physical journal / E
%V 39
%N 9
%@ 1292-895X
%C Berlin
%I Springer
%M FZJ-2016-05765
%P 86
%D 2016
%X Cyclodextrins are cyclic oligosaccharides which are interesting as drug delivery systems, because they can be used as containers for pharmaceutical substances. We studied the Ludwig-Soret effect of $\alpha$-, $\beta$-, $\gamma$- and methyl-$\beta$-cyclodextrin in water and formamide by infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS).In water the Soret coefficient, $S_{\mathrm{T}}$, of $\alpha$-, $\beta$- and $\gamma$-cyclodextrin increases with increasing temperature and shows a sign change from negative to positive around $T=35^\circ$C, while $S_{\mathrm{T}}$ of methyl-$\beta$-cyclodextrin is positive in the entire investigated temperature. In formamide $S_{\mathrm{T}}$-values of all cyclodextrins coincide and show a slight decrease with temperature. We discuss the obtained results and relate the $S_{\mathrm{T}}$-values to the different hydrogen bonding capabilities of the cyclodextrins and the used solvents. It turns out that the change of $S_{\mathrm{T}}$ with temperature correlates with the partition coefficient, log~$P$, which indicates that more hydrophilic substances show a more pronounced temperature sensitivity of $S_{\mathrm{T}}$. Additionally we obtained a surprising result measuring the refractive index contrast factor with temperature, $(\partial n/\partial T)_{c,p}$ of cyclodextrins in formamide, which might be explained by a complex formation between cyclodextrins and formamide.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000384580700001
%R 10.1140/epje/i2016-16086-5
%U https://juser.fz-juelich.de/record/820455