Cavity hydrophobic

The rate acceleration imposed by 0-cyclodextrin was explained in terms of a microsolvent effect 6> The inclusion of the substrate within the hydrophobic cavity of cyclodextrin simulates the changes in solvation which accompany the transfer of the substrate from water to an organic solvent. Uekama et al.109) have analyzed the substituent effect on the alkaline hydrolysis of 7-substituted coumarins (4) in the... 

Figure 34 Chemical formula of y-cyclodextrin consisting of eight glucose molecules with adamantane as the guest entrapped within its hydrophobic cavity. Structures of a- and P-cyclodextrins will be similar but made up of six and seven (n = 6, 7) glucoses,...

The use of chiral ruthenium catalysts can hydrogenate ketones asymmetrically in water. The introduction of surfactants into a water-soluble Ru(II)-catalyzed asymmetric transfer hydrogenation of ketones led to an increase of the catalytic activity and reusability compared to the catalytic systems without surfactants.8 Water-soluble chiral ruthenium complexes with a (i-cyclodextrin unit can catalyze the reduction of aliphatic ketones with high enantiomeric excess and in good-to-excellent yields in the presence of sodium formate (Eq. 8.3).9 The high level of enantioselectivity observed was attributed to the preorganization of the substrates in the hydrophobic cavity of (t-cyclodextrin. 

In addition, cyclodextrins, because of their hydrophobic cavity, are capable of hydrophobic binding of the diene and/or dienophile into the cyclodextrin cavity in water. Therefore, cyclodextrins with the... 

The specific structure of [(H20)5Ni(py)]2+ was observed in the complexes with the second-sphere coordination of calix[4]arene sulfonate.715 There are two different [(H20)5Ni(py)]2+ cations in the complex assembly. In one the hydrophobic pyridine ring is buried in the hydrophobic cavity of the calixarene with the depth of penetration into the calixarene cavity being 4.3 A (Figure 9). The second independent [(H20)5Ni(py)]2+ cation is intercalated into the calixarene bilayer. 

Murakami, Y., Kikuchi, J., Hayashida, O. Molecular Recognition by Large Hydrophobic Cavities Embedded in Synthetic Bilayer Membranes. 175, 133-156 (1995). 

The noncovalent binding of a series of oxo-squaraine dyes 9a-e to BSA was evaluated by measurement of absorption, emission, and circular dichroism [63]. The magnitude of the association constants (Ks) for the dye-BSA complexes depended on the nature of the side chains and ranged from 34 x 103 to 1 x 107 M-1. Depending on the side chains, the Ks increase in the order [R1 = R2 = butyl-phthalimide] < R1 = R2 = cetyl] <[RJ = R2 = ethyl] <<[R = butyl-phthalimide, R2 = butyl-sulfonate] <<[RJ = R2 = butyl-sulfonate]. These dyes seem to interact mainly with a hydrophobic cavity on BSA. However, the association constants Ks increase substantially when the side chains are selected from butyl sulfonate. 

A. Casnati, F. Sansone, and R. Ungaro, Peptido- and glycocalixarenes Playing with hydrogen bonds around hydrophobic cavities, Acc. Chem. Res., 36 (2003) 246-254. 

A number of model studies of the second type have also been investigated. In these, the iron complex provides a hydrophobic cavity so positioned that it surrounds the bound 02 molecule. These include the lacunar complexes mentioned in Chapter 3 (Goldsby, Beato Busch, 1986) particular complexes of which are quite efficient reversible carriers. A further (early) example of this type was (312) which encloses the dioxygen in a rudimentary cavity. However, this species only binds dioxygen reversibly at low temperatures (Baldwin Huff, 1973). 

The recognition of each receptor by its respective hormone is a highly specific process occurring at the LBD. The small hormonal molecule enters a hydrophobic cavity of the receptor molecule, forming a high affinity bond. 

Amorin, M., Castedo, L., and Granja, J. R. (2003). New cyclic peptide assemblies with hydrophobic cavities The structural and thermodynamic basis of a new class of peptide nanotubues./. Am. Chem. Soc. 125, 2844-2845. 

Taking into account the capacity of cyclodextrins (CD-s) to entrap a large number of organic and inorganic molecules, due to their hydrophobic cavity, [3-CD has been introduced into PVA in order to obtain a good separation of isomer mixtures. 

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