abstract
The oligo(ferrocenyldimethylsilanes) FcSiMe(2)Fc and FcSiMe(2)[(eta(5) -C5H4)Fe(eta(5)-C5H4SiMe2)]- Fc [Fe = (eta(5)-C5H5)Fe(eta(5)-C(5)H(4)A were encapsulated in gamma-cyclodextrin (CD) to give crystalline inclusion compounds with 2:1 and 3:1 (host-to-guest) stoichiometries, respectively. A complex between y-CD and ferrocene was also prepared for comparison. The formation of true inclusion complexes was confirmed in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and C-13/Si-29 CP MAS NMR spectroscopy. Powder XRD reveals that the complexes containing ferrocene and the trimer 1,1'-bis(ferrocenyldimethylsilyl)ferrocene have very similar solid-state structures based on channel-type packing of the host molecules. The complexes containing the oligo(ferrocenyldimethylsilanes) dehydrate up to 100 degrees C, after which no mass loss is registered by TGA in the temperature range 100225 degrees C. The dissociation of the complexes occurs slightly above 225 degrees C and is immediately followed by the simultaneous release of the guests and the decomposition of the host in the temperature range 250-310 degrees C. C-13/Si-29 MAS NMR spectra of the inclusion compounds show that the encapsulation of the guest molecules in the CD cavity induces the host macrocycle to adopt a more symmetrical conformation, with each glucose unit in a more similar environment. The inclusion modes are discussed.
keywords
POLY(FERROCENYLSILANE) HIGH POLYMERS; C-13 CHEMICAL-SHIFTS; X-RAY STRUCTURE; BETA-CYCLODEXTRIN; ALPHA-CYCLODEXTRIN; SOLID-STATE; POLY(ETHYLENE GLYCOL); FERROCENE; MODELS; POLYISOBUTYLENE
subject category
Chemistry
authors
Fernandes, JA; Lima, S; Braga, SS; Pillinger, M; Ribeiro-Claro, P; Rodriguez-Borges, JE; Lopes, AD; Teixeira-Dias, JJC; Goncalves, IS
our authors
Isabel Maria de Sousa Gonçalves
Associate Professor
José Alberto Pires Fernandes
Post-doc Fellowship
José J.C. Teixeira Dias
Full professor
Martyn Pillinger
Principal Researcher