resumo
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.
palavras-chave
POLY(FERROCENYLSILANE) HIGH POLYMERS; C-13 CHEMICAL-SHIFTS; X-RAY STRUCTURE; BETA-CYCLODEXTRIN; ALPHA-CYCLODEXTRIN; SOLID-STATE; POLY(ETHYLENE GLYCOL); FERROCENE; MODELS; POLYISOBUTYLENE
categoria
Chemistry
autores
Fernandes, JA; Lima, S; Braga, SS; Pillinger, M; Ribeiro-Claro, P; Rodriguez-Borges, JE; Lopes, AD; Teixeira-Dias, JJC; Goncalves, IS
nossos autores
Isabel Maria de Sousa Gonçalves
Professor associado
José Alberto Pires Fernandes
Bolseiro de pós-Doutoramento
José J.C. Teixeira Dias
Professor Catedrático
Martyn Pillinger
Investigador Principal