Cyclodextrin-water interactions

Danil de Namor AE, Blackett PM, Cabaleiro MC, Al Rawl JMA, Cyclodextrin-monosaccharide interactions in water, J. Chem. Soc., Earaday Trans. 1994 90 845-847. 

Fig. 12 Enantioselective sensing by conformational changes in the sensors, (a) Mechanism of sensing in fluorophore-bearing cyclodextrins by interaction with a guest (b) water soluble imidazolium containing BINOL macrocycles 38, 39 (c) tris- and bis(oxazolmyl)phtaiols (40, 41) (d) l,8-bis(9,9 -diacridyl)naphthalene derivative 42 (e) Stem-Vobner plot of 42 upon interaction with enantiomers of a-halo acids (left 2-chloropropanoic acid, right 2-bromo-3-methylbutanoic acid), showing nonlinear response (from [85] reproduced by permission of The Royal Society of Chemistry)...

Great attention should be paid for the basic investigation and useful application of parent cyclodextrins themselves. Cyclodextrin can interact with two kinds of solutes A and B in water to form a a ternary inclusion complex, CD A B leading to specific condensation of two solutes to form... 

The Effect of Water Vapour on the Cyclodextrin-Solute Interaction in Gas-Solid Chromatography... 

Andera, L. and E. Smolkova-Keulemansova - The effect of water vapour on the cyclodextrin-solute interaction in gas-solid chromatography 289... 

Akiyoshi K, Ueminami A, Kurumada S et al (2000) Self-association of cholesteryl-bearing poly(L-lysine) in water and control of its secondary structure by host — guest interaction with cyclodextrin. Macromolecules 33 6752-6756... 

Similar to the above case, hydroformylation of 1-hexene using a water-soluble rhodium catalyst [RhH(CO)(TPPMS)3] gave lower yields when a-cyclodextrin was added to the biphasic reaction system [14]. Again, the reason was suspected in the interaction between the cyclodextrin and the rhodium catalyst. 

A first example is represented by the Mn(III)/Mn(II) redox switch. The complexes of Mn(II) and Mn(III) with the water-soluble tetraphenylsulpho-nate porphyrin (TPPS, Chart 13) display significantly different ri values at low magnetic field strength (lower than 1 MHz), but very similar values at the fields currently used in the clinical practice (> 10 MHz) (141). However, the longer electronic relaxation rates of the Mn(II) complex makes its relaxivity dependent on the rotational mobility of the chelate. In fact, upon interacting with a poly-p-cyclodextrin, a 4-fold enhancement of the relaxivity of [Mn(H)-TPPS(H20)2] at 20 MHz has been detected, whereas little effect has been observed for the Mn(III)-complex. The ability of the Mn(II)/Mn(III)... 

Very recently a new method was developed that opens the possibility to polymerize even hydrophobic monomers in aqueous solution. This method is based on the finding that hydrophobic monomers can be made water-soluble by incorporation in the cavities of cyclodextrins. It has to be mentioned that no covalent bonds are formed by the interaction of the cyclodextrin host and the water-insoluble guest molecule. Obviously only hydrogen bonds or hydrophobic interactions are responsible for the spontaneous formation and the stability of these host-guest complexes. X-ray diffraction pattern support this hypothesis. Radical polymerization then occurs via these host-guest complexes using water-soluble initiators. Only after a few percent conversion the homogeneous solution becomes turbid and the polymer precipitates. 

Release of two water molecules from the cavity of a-cyclodextrin (form I) (19) is accompanied not only by the loss of van der Waals interaction (/fj jdw) and hydrogen bonding ( —2 A/fH.bond), but also by the gain of motional freedoms of two water molecules as to translation (2S ans) and three-dimensional rotation (2S ,I(3 D)). At the same time, a change in conformational energy of a-cyclodextrin is involved which is estimated by the use of Allinger s method (49). 

Some authors based their approach to selective binding of the more lipophilic a-amino acids in water on hydrophobic effects using water-soluble, cavity-containing cyclophanes for the inclusion of only the apolar tail under renouncement of any attractive interaction of the hosts with the zwitterionic head . Kaifer and coworkers made use of the strong affinity of Stoddart s cyclobis(paraquat-p-phenylene) tetracation 33 for electron-rich aromatic substrates to achieve exclusive binding of some aromatic a-amino acids (Trp, Tyr) in acidic aqueous solution [48]. Aoyama et al. reported on selectivities of the calix[4]pyrogallolarene 34 with respect to chain length and t-basicity of aliphatic and aromatic amino acids, respectively [49]. Cyclodextrins are likewise water-soluble and provide a lipophilic interior. Tabushi modified )S-cyclodextrin with a 1-pyrrolidinyl and a carboxyphenyl substituent to counterbalance the... 

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