TY  - JOUR
AU  - Eguchi, Kazuya
AU  - Niether, Doreen
AU  - Wiegand, Simone
AU  - Kita, Rio
TI  - Thermophoresis of cyclic oligosaccharides in polar solvents
JO  - The European physical journal / E
VL  - 39
IS  - 9
SN  - 1292-895X
CY  - Berlin
PB  - Springer
M1  - FZJ-2016-05765
SP  - 86
PY  - 2016
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000384580700001
DO  - DOI:10.1140/epje/i2016-16086-5
UR  - https://juser.fz-juelich.de/record/820455
ER  -