Charalampopoulos VG, Papaioannou JC, Tsekouras AA, Kakali G, Karayianni HS. Significant modification of the I(-)3 Lewis base character in the β-cyclodextrin polyiodide inclusion complex with Co2+ ion: an FT-Raman investigation.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011;
83:279-287. [PMID:
21925930 DOI:
10.1016/j.saa.2011.08.031]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 08/15/2011] [Accepted: 08/19/2011] [Indexed: 05/31/2023]
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.
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