Chiral selective binding

An agonist, by virtue of the molecular information it contains (e.g., size, 3D configuration, charge distribution, hydrogen- or ionic-bonding residues, chirality), selectively binds to a complementary 3D surface or binding site domain formed by amino acid residues of a receptor protein and initiates a... 

Trigonal ML3 metal complexes exist as optically active pairs. The complexes can show enantiomeric selective binding to DNA and in excited state quenching.<34) One of the optically active enantiomers of RuLj complexes binds more strongly to chiral DNA than does the other enantiomer. In luminescence quenching of racemic mixtures of rare earth complexes, resolved ML3 complexes stereoselectively quench one of the rare earth species over the other. 35-39 Such chiral recognition promises to be a useful fundamental and practical tool in spectroscopy and biochemistry. 

A great variety of macrocyclic polyethers have been shown to bind R-NH3+ molecules with structural and chiral selectivity [2.100-2.103, 2.107]. Extensive... 

These considerations also apply to systems where binding involves interactions other than metal coordination, such as hydrogen bonding or donor-acceptor forces. Such is the case for the chiral selection occurring in the course of the self-assembly of homochiral helical strands (Section 9.4.2) and ribbons (Section 9.4.4) through hydrogen bonding. 

Bradshaw and co-workers reported infrared (IR) vibrational modes of the cryptands, shown in Table 4 <1993JOC7694, 1996JOC7270>, and they determined the optical activity of cryptands 36 and 37 they gave [a] o = ll.Z and —307.8, respectively <1996JOC7270>. Via NMR, 36 and 37 were shown to have some chiral selectivity for binding 16-18. 

It has been reported that several transition metal complexes catalyze the hetero-Diels-Alder reaction between a variety of aldehydes, in particular benzaldehyde, and Danishefsky s diene (Sch. 52). With the [CpRu(CHIRAPHOS)] complex the ee is modest (25 %) (entry 1) [192]. The chiral complex VO(HFBC)2 performs better in this reaction (entry 2) [193]. In experiments directed towards the synthesis of anthra-cyclones, this complex was used in cycloadditions between anthraquinone aldehydes with silyloxy dienes. One example is shown in Sch. 53 [194]. Compared with the chiral aluminum catalyst developed earlier by Yamamoto and co-workers [195], the vanadium catalyst results in lower enantioselectivity but has advantages such as ease of preparation, high solubility, stability towards air and moisture, and selective binding to an aldehyde carbonyl oxygen in the presence of others Lewis-basic coordination sites on the substrate. 

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