P-Cyclodextrins, functionalized

ABSTRACT. The copper(n) complexes of p-cyclodextrins functionalized with aliphatic or pseudoaromatic amines were used for the chiral recognition of unmodified amino acids. Molecular recognition, assisted by non-covalent interactions, was proved by means of thermodynamic and spectroscopic (c.d., e.p.r. and fluorescence) measurements. A cis-disposition of amino groups seems to assist enantiomeric selectivity. The copper(II)-p-cyclodextrin complexes can be used as mobile phase additives in HPLC to separate enantiomeric mixtures of unmodified aromatic amino acids. 

Receptor molecules have also been reported where remarkable enhancement of the binding process is obtained by both cavity interaction and metal-ligand co-ordination interaction [25]. For instance, P-cyclodextrin functionalized with diethylentriamine forms a zinc(II) complex that binds adamantane-2-ketone-l-carboxylate anion 330 times more strongly than the parent P-CD [26]. 

Xu C, Wang X, Wang J, Hu H, Wan L. Synthesis and [4iotoelectrical prt rties of P-cyclodextrin functionalized graphene materials with high bio-recognition capabflity. Chem Phys Lett 2010 498 162-7. 

G.U. Marten, T. Gelbrich, H. Ritter, and A.M. Schmidt, A magnetoresponsive drug dehv-ery system via P-cyclodextrin functionalized magnetic polymer brushes. Magnetics, IEEE Transactions, 49 (1), 364-372,2012. 

Walhagen, A., Edholm, L.E. (1991). Chiral separation of achiral stationary phases with different functionalities using P-cyclodextrin in the mobile phase and applications to bioanalysis and coupled columns. Chromatographia 32, 215-223. 

Rawjee, Y.Y., Stark, D.U., Vigh, G. Capillary electrophoretic chiral separations with cyclodextrin additives I. acids Chiral selectivity as a function of pH and the concentration of P-cyclodextrin for fenoprofen and ibuprofen. J. Chromatogr. 1993, 635, 291-306. 

Breslow s P-cyclodextrine ribonuclease model system represents one of the best examples concerning the construction of small enzyme-like molecules [33]. Breslow functionalized the P-cyclodextrine with two imidazole moieties (Figure 10.1). Selectively, catechol cyclic phosphate carrying a 4-tert-butyl group (Figure 10.1a) binds into the cavity of the catalyst (Figure 10. lb) in water solution, and is then hydrolyzed by the... 

The host-guest p-cyclodextrin-C522 complex formation was determined based on fluorescence blue shift as a function of the increasing p-cyclodextrin concentration from 10 6 to 10 2 M. Similar result was observed for coumarin C6 [4] and this blue shift was considered along with anisotropy results as a proof of the host-guest formation. Time-resolved fluorescence spectroscopy was utilized to differentiate between fluorescence dynamics of... 

Marchelli used the copper(II) complex of histamine-functionalized P-cy-clodextrin for chiral recognition and separation of amino acids [27]. The best results were obtained for aromatic amino acids (Trp). Enantioselective sensing of amino acids by copper(II) complexes of phenylalanine-based fluorescent P-cyclodextrin has been recently published by the same author [28, 29]. The host containing a metal-binding site and a dansyl fluorophore was shown to form copper(II) complexes with fluorescence quenching. Addition of d- or L-amino acids induced a switch on of the fluorescence, which was enantioselective for Pro, Phe, and Trp. This effect was used for the determination of the optical purity of proline. 

Kinetic experiments Either PMHS or HMS-301 reacted in toluene at 60 °C with peracetylated monoaUyl P-cyclodextrin in stoichiometric amounts with respect to Si-H. The concentration of P-cyclodextrin and Si-H was 0.032mol/L. The concentration of Karstedt catalyst was 20ppm of platinum content. Ahquots of the reaction medium were coUected at different times and the solutions were directly analyzed by IR spectroscopy in a hquid cell. The absorbance of the Si-H band at 2160cm was normalized to the absorbance of the C=0 stretching band of the ester at 1740cm . The decrease of the Si-H band was plotted as a function of time. The conversion is the complement to 100%. 

Organosilica Mesoporous Materials with Double Functionality Amino Groups and p-Cyclodextrin Synthesis and Properties... 

Native -cyclodextrin is not reactive enough to be condensed directly with APS, so a modihed cyclodextrin is needed. Monotosyl-P-cyclodextrin is the most used to prepare mono-functionalized cyclodextrins. 

FIG. 7.27 (A) The assembly of a P-cyclodextrin mortoJayer on a Au-electrode. (B) Cyclic voltammo-grams of Che -CD-functionalized Au-electrode in the presence of (a) 22a and (b) 22b at I gM. Insec Photoswitching behavior of the cathodic peak current. Experiments were performed in 0.01 M phosphate buffer (pH 10.8) at a scan rate of 100 mV s. (Adapted from reference 99, Figure I. Reproduced by permission of The Royal Society of Chemistry.)... 

A mixed-mode, or multimodal, CSP is one that has been designed to operate with two or more different types of chiral recognition mechanisms. Armstrong et al. (19,78) have developed such a CSP by reacting p-cyclodextrin with (K)- or (S)-naphthyl-ethylisocyanate. The resulting naphthylethylcarbamate derivative of p-cyclodextiin, the NEC-p-CD CSP can function as either a type I CSP or ty III CSE... 

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