Chiral recognition is an important subject in biological, medical, or pharmaceutical systems. Focusing on natural amino acids, their optical purity or ee values normally are determined analytically with chiral columns. [1][2][3] Cyclodextrins (CDs) are chiral, naturally occurring cyclic oligosaccharides, which, due to the unique molecular structure, are able to form inclusion (host-guest) complexes with various polymers. 4,5 The first stereoselective inclusion of a whole polymer chain with CDs was shown by Tonelli et al., who demonstrated that only isotactic poly(3-hydroxy butyrate) can be included in a R-CD cavity, while atactic poly(3-hydroxy butyrate) cannot. 6 Accordingly, the enantioselective enclosing of isotactic polylactides with CD rings was published by Yui et al. in 2007. 7 We demonstrated recently that in the case of a free radical polymerization of a CD complexed N-methacryloyl-D,L-phenylalanine methyl ester racemic mixture the D-enantiomer polymerizes preferentially, whereas the L-enantiomer tends to accumulate in the solution. 8 Up to now, the enatioselective inclusion of chiral side groups of synthetic polymers with CD has not been investigated. Herein, we demonstrate the chiral recognition of the polymeric bound amino acid with RAMEB-CD (random methylated β-cyclodextrin). Generally, the glucose-based CDs might distinguish between native D-and L-amino acid enantiomers in aqueous media due to diastereomeric effects. 9-12 Thus, D-and L-tryptophan (D-and L-Trp) became the focus of our interest as chiral model compounds. It is an essential amino acid implemented in proteins with an aromatic moiety and therefore suitable to build inclusion complexes with RAMEB-CD. [13][14][15] Also, L-Trp is a precursor of serotonin, which is commonly used in pharmaceutical application as a tranquillizer. Furthermore, because of the presence of two functional domains, the amino and carboxylic groups D-and L-Trp are an interesting species for polymer synthesis.The D-and L-Trp-based monomers are synthesized when the amino groups of the amino acid are modified via condensation reaction, while the free carboxylic group, sensitive to pH value, still remains. The remarkable polymer properties based on poly-(N-isopropylacrylamide) (poly(NIPAAm)) induced us to select the NIPAAm as comonomer for direct copolymerization procedures. It is well-known that poly(NIPAAm) is a typical thermoresponsive polymer exhibiting a lower critical solution temperature (LCST) behavior in aqueous media at around 32 °C. 16 Above this critical temperature the polymer precipitates a stage that is reversible as soon as the temperature sinks below the LCST. The important feature is that the poly(NIPAAm) LCST value bears a tunable character due to the existence of a delicate

SummaryIn the present work we report the enantioselective recognition of water soluble stimuli-responsive polymers bearing phenylalanine moieties via host-guest interaction with β-cyclodextrin and randomly-methylated-β-cyclodextrin (RAMEB-CD). We synthesised N-acryloyl-D/L-phenylalanine monomers (2 D, 2 L) which were then copolymerised under free radical conditions with N-isopropylacrylamide (NIPAAm). The resulting copolymers 3 D and 3 L exhibit a lower critical solution temperature (LCST) of 25 °C. As a further benefit, the presence of a free carboxylic group in the copolymer system gives a high sensitivity to the pH value in respect to the LCST value. The enantioselective recognition of the side groups of copolymers 3 D and 3 L and their solubility behaviour were investigated by dynamic light scattering and 2D NMR spectroscopy, respectively.

We report the preparation of acrylic monomers D-or Lmono-(6-phenylalanine-acrylamido-6-deoxy)-β-cyclodextrin 3 D /3 L and their corresponding copolymers 4 D /4 L bearing NIPAAm and D-or Lphenylalanine as guest and β-cyclodextrin as host moieties. To implement the cyclodextrin resin (CD) into the monomer, microwave accelerated cycloaddition (click-reaction) was performed. For the new design of polymers having both host and guest species in the polymer side chain, inter-and intramolecular interactions could be observed. The resulting supramolecular structures were characterized by NMR, DLS, TEM, and LCST measurements.

SummaryIn this work we demonstrate chiral recognition of (+)- and (−)-ephedrine using a cyclodextrin-containing polymer. The supramolecular structures obtained by complexation of ephedrine and cyclodextrin were verified by 2-D ROESY NMR measurements. Dynamic light scattering showed clear differences in the mean coil size.

SummaryThe enzymatically catalyzed synthesis of a copolymer of 4-tert-butylphenol and 4-ferrocenylphenol by horse radish peroxidase (HRP) in the presence of H2O2 in a 1,4-dioxane/water system is described. Furthermore, polymer-analogous alkylation of the free hydroxy groups and subsequent click reaction with mono-6-azido-6-desoxy-β-cyclodextrin (N3-β-CD) was carried out. The formation of inter- and intramolecular inclusion complexes was investigated by DLS measurement.