Chiral groove

For applications and development of chiral resolution methods, it is essential to have knowledge of the chiral resolution mechanism on polysaccharide-based CSPs. At the molecular level, this mechanism is still unclear because of difficulties associated with spectroscopic studies, as discussed earlier. Nevertheless, some experimental efforts have been made, and chiral resolution reportedly has been achieved through different types of bonding on the chiral grooves of polysaccharide-based CSPs. 

The chiral recognition can also be observed by NMR spectroscopy. Figure 14 shows the recognition of the enantiomers 18 by NMR spectroscopy [32]. The resonances of the C1-C4 and CIO carbons of 18, which are located near the hydroxy groups, are separated into enantiomers in the presence of 6r, and the carbon resonances of (5)-18 clearly become broader than that of (R)-18 as well as the observation in the NMR spectrum. This indicates that ring A of (5)-18 may be favorably located in the chiral groove of 6r. Measurements of the relaxation time also support this speculation. 

The interaction energy difference between the enantiomers was clearly reeog-nized only when the enantiomers were generated in a chiral groove of 6f and 6p. This result indicates that the polar carbamate groups of these phenylcarbamate derivatives may be the most important chiral recognition site for polar racemates. 

Herman, D.M., E.E. Baird, and P.B. Dervan. Stereochemical control of the DNA binding affinity sequence specificity, and orientation preference of chiral hairpin polyamides in the minor groove. J. Am. Chem. Soc. 1998, 120, 1382-1391. 

Fig. 7 Schematic view of the different approaches used to model the chiral interactions between DNA double helices, (a) DNA duplexes are viewed as clean cylinders with charged helical patterns of negative phosphates and positive adsorbed counterions. Reproduced with permission from [18], (b) Duplexes interact via steric interlocking of backbone and grooves and through electrostatic repulsion of the phosphate groups. Reproduced with permission from [14]...

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