Cyclic Receptor

In the last few years, Hamilton has published reports of a series of open chain or cyclic receptors featuring 2-acylaminopyridine units as combined H-bond donor and acceptor groups [30]. The simple terephthaloyl derivative 22 forms stable complexes with dicarboxylic acids of appropriate chain length, like adipic and glutaric acid, in CDCI3 [31]. Additionally, complexation influences the s-cis s-trans ratio of the amide bond in acylprolines [32]. 

Joshi P, Joshi N, Sharma U. Extraction and carrier-facilitated transport of amino acids using synthetic non-cyclic receptors through bulk hquid membrane. Indian J Biochem Biophys 2006 43 323-326. 

Lehn. J.M. Cryptates Inclusion complexes of macropoly-cyclic receptor molecules. Pure Appl. Chem. 1978. 50. 871. 

Beer, P.D. Keefe. A.D. A new approach to the coordination of anions, novel polycobalticinium macro-cyclic receptor molecules. J. Organomet. Chem. 1989. 375. C40. 

The importance of the template concentration is illustrated by the behavior of the small disulfide DCL shown in Figure 2.5, which features two different macro-cyclic receptors 17 and 18 that both bind ammonium guest 16, with host 18 binding the strongest [20]. Thus, if amplification would be selective for the fittest... 

Comparison of the relative affinities of nucleotides of acyclic and cyclic receptors is also interesting. Although not much data regarding this point can be found in the literature, several years ago a study was published that compared the relative affinities of the cyclic receptors [ISJaneNe (7), (CH3)4[18]aneN6 (21) and of the acyclic receptor (CH3)2pentaen (22) (Scheme 7) for ATP. ... 

However, in cases where the complementarity between the nucleotide and the cyclic guest species is optimum, higher interaction should be expected for the cyclic receptor. 

H-bonding sites similar to cyclic receptor 9a, they interacted with anions much more weakly than the cyclic analogue due to the lack of the macrocyclic effect. 

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