Preparation and Characterization of Inclusion Complexes of Poly(propylene glycol) with Cyclodextrins

Abstract

3-Cyclodextrin (/3-CD) and y-cyclodextrin (y-CD) form inclusion complexes with polypropylene glycol)s (PPG) of various molecular weights to give stoichiometric compounds in crystalline states. -Cyclodextrin (a-CD) did not form complexes with PPG of any molecular weight, ß-and y-CD did not form complexes with the low molecular weight analogs, such as propylene glycol, di(propylene glycol), and tri(propylene glycol). The yields of the complexes of ß-and y-CD with PPG increased with increasing molecular weight (MW) of the PPG and reached a maximum at about MW 1000; yield decreased with a further increase in the MW. They were isolated and found to be 2:1 (monomer unit:CD). The complexes were characterized by IR, NMR, 13C NMR, 13C CP/MAS NMR, and 13C PST/MAS NMR spectra and X-ray (powder), thermal, and elemental analyses. Complex formation of CDs with PPG derivatives has also been studied. The structures of the complexes are discussed. Complex formation of /3-CD with atactic and isotactic PPG has been compared.

Preparation and Characterization of Inclusion Complex between β-Cyclodextrin and Polylactic Acid

“…Meanwhile, the characteristic peaks for β-CD at 2θ=6.53 and 9.3 o in the inclusion complexes were nearly not seen. The patterns of the β-CD-PLA ICs were similar to that of the inclusion complex between β-CD and PPG, 35 PDXL, 36 PDMS, 37 which had been reported to have the columnar structure. Therefore, the ICs of PLA with β-CD also likely assumed a columnar structure.…”

“…CD: PLA, mol: mol) of ICs could be calculated by the integration of NMR resonances belonging to CD blocks at 4.83 ppm and to PLA blocks at 1.5 ppm. [27][28][29] It is known that β-CD molecule possesses the unique structure of a torus where H-3 and H-5 protons are located inside the cavity, while H-2 and H-4 are outside the torus; if β-CD can form inclusion complexes with PLA, the chemical shifts of the proton H-3 or H-5 will change at a certain extent because of the short-distance intermolecular interactions and hydrogen bond effects. From Figure 4(c), the peaks responding to H-3 and H-5 of β-CD molecular shifted slightly to a high frequency, in comparison to the spectrum line b, which also accounted for the formation of a channel-type structure in the inclusion complexes.…”

Cyclodextrin-covered organic nanotubes derived from self-assembly of dendrons and their supramolecular transformation

“…In addition, the resonances of methyl protons of PPG entrapped in the cavity of ␥-CD were observed in 1 H NMR spectra (see Fig. 12, which is published as supporting information on the PNAS web site) (29). These results indicate that focal ␥-CD is removed from the nanotube and taken up by PPG to form pseudorotaxane.…”

“…Therefore, we reasoned that CD inclusion would trigger the transformation of supramolecular structures induced by self-assembly of the dendrons with a focal pyrene unit. In addition, removal of CDs from the focal inclusion complex moiety by using a CD-poly(propylene glycol) (PPG) pseudorotaxane motif (29) would provide a unique route to the reversal of the supramolecular structure. In addition, pyrene has unique fluorescence characteristics depending on the environmental condition, which is very useful for monitoring the transformation of the organized structures.…”

Self-Assembled Supramolecular Gels of Reverse Poloxamers and Cyclodextrins

“…1a) 3,5,10 . Cyclodextrins yield inclusion complexes also with PEO/PPO block copolymers yielding selective polyrotaxanes depending on the type of CD used [11][12][13][14] . β-and γ-CD form complexes with PPO blocks 14,15 and α-CD interacts with PEO blocks 16,17 .…”