title: Significant modification of the I(-)3 Lewis base character in the β-cyclodextrin polyiodide inclusion complex with Co2+ ion: an FT-Raman investigation.
abstract: The β-cyclodextrin (β-CD) polyiodide inclusion complex (β-CD)(2)·Co(0.5)·I(7)·21H(2)O has been synthesized, characterized and further investigated via FT-Raman spectroscopy in the temperature range of 30-120°C. The experimental results point to the coexistence of I(-)(7) units (I(2)·I(-)(3)·I(2)) that seem not to interact with the Co(2+) ions and I(-)(7) units that display such interactions. The former units exhibit a disorder-order transition of both their I(2) molecules above 60°C due to a symmetric charge-transfer interaction with the central I(-)(3) [I(2)←I(-)(3)→I(2)], whereas in the latter units only one of the two I(2) molecules becomes well-ordered above 30°C. The other I(2) molecule remains disordered presenting no charge-transfer phenomena. The Co(2+) ion induces a considerable asymmetry on the geometry of the I(-)(3) anion and a significant modification of its Lewis base character. Complementary dielectric measurements suggest no important involvement of H···I contacts in the observed modification of the I(-)(3) electron-transfer properties.
authors.affiliation: Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens, Greece. v_charalampopoulos@yahoo.gr
authors.forename: Vasileios G
authors.initials: VG
authors.lastname: Charalampopoulos
authors.forename: John C
authors.initials: JC
authors.lastname: Papaioannou
authors.forename: Athanasios A
authors.initials: AA
authors.lastname: Tsekouras
authors.forename: Glikeria
authors.initials: G
authors.lastname: Kakali
authors.forename: Haido S
authors.initials: HS
authors.lastname: Karayianni
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D004579:Electron Transport; D005583:Fourier Analysis; D007454:Iodides / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D058115:Lewis Bases / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D007454:Iodides; D007477:Ions; D058115:Lewis Bases; D047392:beta-Cyclodextrins; D003035:Cobalt