Dielectric and Raman spectroscopy of the heptaiodide complex (beta-cyclodextrin)(2)center dot CsI7 center dot 13H(2)O

Charalampopoulos, VG; Papaioannou, JC; Karayianni, HS

dc.contributor.author	Charalampopoulos, VG	en
dc.contributor.author	Papaioannou, JC	en
dc.contributor.author	Karayianni, HS	en
dc.date.accessioned	2014-03-01T01:55:31Z
dc.date.available	2014-03-01T01:55:31Z
dc.date.issued	2006	en
dc.identifier.issn	1293-2558	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/27777
dc.subject	dielectric properties	en
dc.subject	Raman spectra	en
dc.subject	beta-cyclodextrin complex	en
dc.subject	heptaiodide ions	en
dc.subject	flip-flop hydrogen bonds	en
dc.subject	calorimetric measurement	en
dc.subject.classification	Chemistry, Inorganic & Nuclear	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	CYCLODEXTRIN-POLYIODIDE COMPLEXES	en
dc.subject.other	RAY CRYSTAL-STRUCTURES	en
dc.subject.other	INCLUSION COMPLEXES	en
dc.subject.other	NEUTRON-DIFFRACTION	en
dc.subject.other	TOPOGRAPHY	en
dc.subject.other	UNDECAHYDRATE	en
dc.subject.other	RELAXATION	en
dc.subject.other	MECHANISM	en
dc.subject.other	SPECTRA	en
dc.title	Dielectric and Raman spectroscopy of the heptaiodide complex (beta-cyclodextrin)(2)center dot CsI7 center dot 13H(2)O	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2006	en
heal.abstract	The frequency and temperature dependence of the real and imaginary parts of the dielectric constant (epsilon', epsilon"), the phase shift (phi) and the acconductivity (a) of the polycrystalline (beta-Cyclodextrin)(2)center dot CSI(7)center dot 13H(2)O (beta-Cs) have been investigated over the frequency and temperature ranges of 0-100 kHz and 140-425 K, respectively, in combination with Raman spectroscopy and DSC. The epsilon'(T), epsilon"(T) and phi(T) variations at frequency 300 Hz in the range 140 K < T < 300 K show two sigmoids, two bell-shaped curves and two minima, respectively, revealing the existence of two kinds of water molecules, tightly bound and easily movable ones. beta-Cs shows the transition of normal hydrogen bonds to those of flip-flop type at 199.9 K. As the temperature increases most of the thirteen water molecules per cyclodextrin dimer remain tightly bound and only a small number of them become easily movable. The DSC trace shows a small endothermic peak with an onset temperature of 80 degrees C, which is related to the easily movable water molecules. Strong peaks at 115 and 135 degrees C are caused by the tightly bound water molecules and the sublimation of iodine, respectively. The Cs+ ions contribute to the ac-conductivity via a Grotthuss mechanism with an activation energy 0.64 eV when all the water molecules exist in the crystal lattice and 0.45 eV when the easily movable water molecules start to escape. The Raman peaks at 179, 170 and 166 cm(-1) are due to the (I2I3-I2)-I-.-I-. polyiodide chains consisting Of I-3(-) units indicating charge transfer interactions and lengthening of 12 units, respectively. The charge Of I-7(-) units remains localized with negligible contribution to the conductivity until the sublimation of iodine starts. (c) 2005 Elsevier SAS. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	SOLID STATE SCIENCES	en
dc.identifier.isi	ISI:000234739300015	en
dc.identifier.volume	8	en
dc.identifier.issue	1	en
dc.identifier.spage	97	en
dc.identifier.epage	103	en