Stereospecific interaction

One may consider a series of physical states ranging from the crystalline, where molecular aggregation and orientation are large, to the dilute gaseous state, where there are no significant orientational limits. States of intermediate order are represented by micelles, liquid crystals, monolayers, ion pairs, and dipole-dipole complexes. In the crystalline state, the differences between pure enantiomers, racemic modifications, and diastereomeric complexes are clearly defined both structurally and energetically (32,33). At the other extreme, stereospecific interactions between diastereomerically related solvents and solutes, ion pairs, and other partially oriented systems are much less clearly resolved. 

The same stereospecific interaction found with Ru(phen)3 or Ru(DIP)3 enantiomers with DNA of different helicities, has been observed in the photocleavage reactions by the corresponding Co (III) enantiomers, as indicated by the specific cleavage of left-handed DNA by /l-Co(DIP)t [148]. The use of... 

Admittedly, the separation of enantiomers is often difficult and expensive. However, now that we are in the 21st century, the need for optically active drugs capable of stereospecific interactions with drug receptors is a recognized prerequisite in drug design. 

Affinity chromatography has become the method of choice for purifying macromolecular substances and for determining the nature of the stereospecific interactions of these substances.1,2 The method has... 

Liquori, A. M., G. Anzuino, V. M. Coiro, M. D Ax.agni, P. DeSantis, and M. Sarino Complementary stereospecific interaction between isotactic and syndiotactic polymer molecules. Nature 206, 358 (1965). 

Drude first proposed that the rotatory power of a dissymmetric substance could be understood if its absorption of light involved the motion of a charged particle along a helical path within the molecule [8]. This type of motion would result in the simultaneous production of an electric dipole from the translatory motion and a magnetic dipole from the rotatory motion. The model requires that the electric and dipole moments have at least some components which are collinear with each other, or else stereospecific interaction with circularly polarized light would not be possible. 

Different mechanisms have been devised to achieve chiral resolution by electromigration, but often we have to deal with mixed-mode separations rather than pure processes. In any case, chiral resolution results from stereospecific interactions of a chiral selector, with the enantiomers of the compound giving rise to a difference in migration velocity between the two entities. Chirally selective ligands, such as Cu(II)-L-histidine and Cu(II)-aspartame, have been used for derivatized amino acid mixtures. 

R. Thompson, Z. Ge, N. Grinberg, D. Ellison, and P. Tway, Mechainistic aspects of the stereospecific interaction for aminoindanol with a crown ether column. Anal. Chem. 67 (1995), 1580-1587. 

Aurbach GD, Fedak SA, Woodard CJ, Palmer JS, Hauser D, Troxler F. P-adrcn-ergic receptor stereospecific interaction of iodinated fi-blocking agent with high affinity site. Science 1974 186 1223-1224. 

The receptors exhibit the tendency toward stereospecific interaction. 

Interestingly, highly stereospecific interaction of BIBP 3226 with the human Y1 receptor expressed in SK-N-MC cells could be shown by the drastically reduced receptor binding affinity (h Y1, IC5o> 10 000 nM) of the corresponding (S)-enantiomer of BIBP 3226. 

Stereospecific Interaction of Benzene with Lithium Chelates. As we have noted, the marked H chemical shift of the chelating agent -CH2-... 

In the a-cyclodextrin accelerated cleavage of (15) the catalytic rate constant for the (/ ) ( —) enantiomer is 35.6 times larger than that for the (S) ( + ) enantiomer. This difference arises from the stereospecificity of the inclusion complexes, since the (S) ( + ) enantiomer, which is less accelerated, binds to a-cyclodextrin more strongly than the (i ) ( —) enantiomer, which is more accelerated. It was proposed that the stereospecific interaction(s) of the included enantiomers with the hydroxyl groups at the asymmetric C-2 atom and/or the asymmetric C-3 atom of the cyclodextrin in the inclusion complexes govern this asymmetric catalysis. 

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