Complexation of Pyrene by Poly(allylamine) with Pendant β-Cyclodextrin Side Groups

Abstract

The complexation of pyrene into the cavity of -cyclodextrin ( -CD) has been studied in aqueous solutions of pure -CD and -CD substituted poly(allylamine) by using fluorescence spectroscopy. Two different approaches to obtain the association constant, both already described in the literature, are compared. It is shown that the evaluation of the fluorescence intensities of the first and third vibronic band of the pyrene fluorescence spectrum gives the correct result because the different quantum yields of free and complexed pyrene are considered correctly. The sole analysis of the Ham effect of pyrene leads to too high values of the association constant. A subsequent formation of 1:1 and 2:1 complexes between -CD and pyrene was confirmed. The synthesized -CD polymers exhibit a significant change in the complexation behavior depending on the degree of substitution (DS). At high DS (up to 23%) only 2:1 complex formation was observed, an evidence for intramolecular, chelate-like complexes due to the high local -CD concentration. At low DS (below 5%) 2:1 complexes are formed only intermolecularly. Compared with pure -CD, the overall complexation constant of the -CD polymers increases by more than 2 orders of magnitude with increasing DS and is independent of the polymer molecular weight. The supramolecular structure of the complex is not changed due to the linkage of the cyclic oligosaccharide to the polymer chain.

Noncovalently connected micelles based on a β‐cyclodextrin‐containing polymer and adamantane end‐capped poly(ε‐caprolactone) via host–guest interactions

“…Water soluble polymers bearing β‐CD groups can be prepared in different ways, that is, polycondensation of CDs or CD derivatives with proper bifunctional agents such as epoxy‐based reactive monomers,18, 19 covalent attachment of CD to linear functional polymers,20–23 and polymerization of monosubstituted acryloyl‐CD derivatives 24, 25. In this work, water soluble polymers PnvpCD were prepared by free radical copolymerization of β‐CD‐containing monomer AEMACD and NVP in aqueous solution.…”

Polymers Containing Covalently Bonded and Supramolecularly Attached Cyclodextrins as Side Groups

“…At low DS (below 5%) 2 : 1 complexes were formed only intermolecularly. Compared to pure bCD, the overall complexation constant of the bCD-polymers increased by more than two orders of magnitude with increasing DS and was independent of the polymers molecular weight [34].…”

“…This substitution reaction on 9b with a polymeric nucleophile has been applied more often, though with different polymers. As well as poly (allylamine) [28,[33][34][35], poly(vinylamine) [36][37][38][39][40], linear [38] and branched poly (ethylenimine) [38][39][40] and poly(ethylene glycol-block-aspartamide) [41] were used. However, for polymers which do not contain highly nucleophilic amino groups, other strategies had to be developed.…”

Cyclodextrin Polymers

“…Poly(allyl amine) was also reacted with monotosylated -CyD [71] and the chelating properties of the obtained polymer for pyrene were studied [72][73][74]. The formation of supramolecular, chelate-type structures of pyrene--CyD-poly(allyl amine) were observed; the chelate association constants are higher than for -CyD and could be controlled by the degree of substitution, pH and presence of polyelectrolytes (Scheme 4).…”