Preparation and Characterization of Inclusion Complexes of Poly(dimethylsiloxane)s with Cyclodextrins

Abstract

β-Cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) formed inclusion complexes with poly(dimethylsiloxane)s (PDMS) of various molecular weights to give crystalline compounds. However, α-cyclodextrin (α-CD) did not form complexes with PDMS of any molecular weight. The yields of the β-CD−PDMS inclusion complexes decreased with increasing molecular weight of PDMS. In contrast, the yields of the γ-CD−PDMS inclusion complexes increased with increasing molecular weight, reached a maximum at molecular weight of around 760, and gradually decreased at higher molecular weight. The chain-length selectivity is reversed between β-CD and γ-CD. The β-CD−PDMS inclusion complexes are stoichiometric 1:1 compounds when the molecular weights of PDMS are low. The γ-CD−PDMS inclusion complexes are stoichiometric 2:3 (cyclodextrin:monomer unit of PDMS) compounds. The complexes were isolated and characterized by 1H NMR, 13C CP/MAS NMR, and X-ray diffraction studies. The inclusion modes are discussed.

Preparation and Characterization of Inclusion Complexes of β‐Cyclodextrin with Ionic Liquid

“…In Figure 3a, major peaks at 9.5, 12.8, 13.3, and 18.18 are observed, indicating that b-CD represents a typical cage structure. [11,18,20,22] The pattern of 1 (Figure 3b) shows some sharp reflections, the main two of which at 2q = 11.6 and 17.88 represent a head-to-head channel-type structure, [25] which is different from that of b-CD. [11,18,20,22] The results indicate that the inclusion complex formed from b-CD and bmimPF 6 is isomorphous with a channel-type structure rather than the socalled "cage" structure.…”

“…[41] There is credible evidence that the hydrogen bonds between CDs play an important role in stabilizing the complexes. [11] Solid-state 13 C CP/MAS (cross-polarization magic-angle spinning) NMR spectroscopy: High-resolution NMR spectroscopy is another technique used to analyze the structure and molecular dynamics of ICs either in aqueous solution or in the solid state. It is known that the formation of the ICs should change the conformation and the electromagnetic environment of both the host CD and the guest molecules, which should be reflected in the 13 C CP/MAS NMR spectra of the host and the guest molecules in the ICs.…”

“…It is known that the formation of the ICs should change the conformation and the electromagnetic environment of both the host CD and the guest molecules, which should be reflected in the 13 C CP/MAS NMR spectra of the host and the guest molecules in the ICs. [11,17,20,21] Figure 4 shows the 13 C CP/MAS NMR spectra of the uncomplexed b-CD and 1. The b-CD molecules are known to have a less symmetrical conformation in the crystalline state.…”

Sol‐Gel‐Sol Transition of Gold Nanoparticle‐Based Supramolecular Hydrogels Induced by Cyclodextrin Inclusion

“…5, 13.6, 18.1, and 22.78, and are consistent with that of SHb-CD, [9] which indicates that they both form cage structures. [10] The pattern for the dehydrated gel, especially the weak and strong peaks at 11.8, 15.2, 17.5, 19.0, and 23.48, however, are quite different from that of b-CD or SH-b-CD, but similar to that of the inclusion complexes between b-CD and some polymers. [9,11] Also, the X-ray pattern of the hydrogel displays no obvious diffraction peaks for the existence of abundant water.…”

Nanorod formation of cyclodextrin-covered sudan dyes through supramolecular self-assembly

“…[11] During the synthesis of supramolecular nanorod aggregates in an aqueous solution, the nanorod dissociates to form into vesicle structures due to the CD introduction. [12] For example, Harada et al prepared CD-reliant polypseudorotaxanes and polyrotaxanes through threading of several CD components onto a polymer chain [13][14][15][16] and then combined them into molecular tubes through the covalent crosslink of adjoining CD components in a polyrotaxane. [6,16,17] Pistolis and co-worker reported the formation of nanotube in b-CD and g-CD due to the intermolecular hydrogen bonding formation between adjacent CDs.…”