Carboxylate binding

Zhn and coworkers have developed SwAr-based macrocyclizadon via biaryl ether formation. The first example of SivAr-based macrocyclizadon for synthesis of model carboxylate-binding pocket C-O-D rings of vancomycin was reported in 1994 fScheme 9.3. ... 

R2Sn(rV)] derivatives of N-Bz-Gly-Gly and N-Bz-Gly-Gly-Gly were found to involve both dicarboxylate binding to yield hexacoordinated Sn centers, and dimeric tetraorganodistannoxanes in which the carboxylates bind... 

The effect of variation in the N-l side-chain of (26) on activity was also examined [52]. In the benzazepinone series (26, n = 2), no loss of activity occurred on extension of the side-chain from acetic acid (m = 1) to propanoic acid (m = 2). The butanoic acid homologue (m = 3) resulted in only a slight decrease in activity, whereas the next higher homologue (m = 4) became 1000-fold less active. These results imply unexpected degrees of freedom at the carboxyl binding site. 

Sr2+ so well that it was selectively extracted from a bulk sample of a barium salt (Helgeson et al., 1973a). Binding constants for metal-cation complexes of 1,3-xylyl-crown ethers [66]—[69] carrying an additional carboxylate binding... 

A new PET-based chemosensor for uronic and sialic acids utilizing the cooperative action of boronic acid and metal chelate was reported by Shinkai and co-workers. This group synthesized a novel fluorescent chemosensor molecule bearing both an o-aminomethylphenylboronic acid group for diol binding to a saccharide and a l,10-phenanthroline-Zn(II)chelate moiety for the carboxylate binding, which enables this sensor to discriminate between neutral monosaccharides and acidic compounds [110],... 

The all-important finding that carboxylate-appended sapphyrins can self-assem-ble was confirmed in the case of the sapphyrin monocarboxylate 6. ° For both compounds the self-assembly phenomena were shown to take place not only in the solid state, but also in solution and in the gas phase (see Section 3.3). This meant that the carboxylate-binding properties of the sapphyrins could be used as the key molecular recognition basis for engendering the spontaneous self-assembly of appropriately designed supramolecular ensembles. 

In analogy to the carboxylate binding by zinc-containing cyclodextrin 10 (see Sect. 2), Lewis acidic centers such as a copper(II) histamine unit may also serve for the chelation of the (deprotonated) 2-aminoacetate substructure of a-amino acids [51], Rizzarelli, Marchelli et al. used a respective j8-cyclodextrin derivative for the formation of the ternary complexes 36 and 37 with racemic... 

Carboxylates bind readily to transition metal cations (42). They are common in coordination chemistry and play a significant role at the active sites of many metalloproteins (43). 

Fig. 9. Potential carboxylate binding modes. The modes shown on the top row are considered explicitly in developing LFMM parameters although anti-anti and anti-syn bridging modes are within the scope of...

For covalently attached dyes, the mechanism is more complex, involving trap states as intermediates and entailing coupled proton transfer. Why do the mechanisms differ It appears likely that phosphonate- and carboxylate-binding perturb semiconductor surfaces sufficiently to create new trap states that can be rapidly populated following injection. The states are necessarily spatially proximal to the attached dyes, but apparently sufficiently separated from each other to preclude fast trap-to-trap hopping. 

The oxidation of homoserine by Cr(VI) has been compared with that of simple alcohols and 4-hydroxybutyric acid (HBA). The formation of CrOj during the oxidation was taken as evidence for the intermediacy of Cr(II). Whilst the rate law for homoserine has a first- and a second-order term, the rate laws for alcohols and HBA display only the second-order term. The second-order rate constants for HBA and homoserine are similar (suggesting that the ammo group of homoserine does not participate in binding to the chromium in this pathway), and about 10 times lower than for the alcohols, accounted for in terms of carboxylate binding to Cr(VI) in the intermediate ester (2), lowering the rate. The additional first-order term seen only for homoserine must arise from involvement of the amino group and this additional pathway is proposed to proceed via a tricyclic intermediate (l).13... 

Hughes, M. P., Smith, B. D., Enhanced carboxylate binding using urea and amide-based receptors with internal Lewis acid coordination A cooperative polarization effect. J. Org. Chem. 1997, 62, 4492—4499. 

Fig. 2.3.2. Carboxylate binding within the active site of Carboxypeptidase A.

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