Recognition double molecular

Molecular recognition Double-helical DNA is able to interact with ligands, e.g. DNA-binding proteins, often in a very site-selective way, providing the basis for the modulation of electron transport. 

Since this assay format involves a double molecular recognition, the selectivity is considerably improved. This format is, however, limited for use with larger antigens that have the intrinsic ability to bind two different antibodies to two different epitopes and is thus not applicable to small haptens. 

The foniiation of 4, therefore, involved several different noncovalent interactions. The cyclization step was brought about by the formation of Pd—N coordinate bonds that is, by a metal-mediated process. The interlocking step involved n- and hydrophobie/hydrophilic-mediated processes, along with an entropic effect. Catenane 4 can. therefore, be considered an example of a multi-mediated,"" multiple-interaction self-assembly. Fujita referred to such processes as ""double-molecular recognition"" procedures, in which the two interlocking molecules bind each other in their cavities. 

Polytopic macrocyclic receptors 1, 2 (Figure 10.1) are able to complex the zwitterionic form of the amino acids by a double non-covalent charge interaction [28,29]. The unsymmetrical benzocrown sulfonamide derivative, 2 which contains benzo-18-crown-6 and benzo-15-crown-5 moieties was used as a ditopic receptor for multiple molecular recognition of the amino acids, by combining two non-covalent interactions ammonium-crown hydrogen bonding and carboxylate- complexed Na+-benzo-15-crown-5 charge interactions [28,33]. 

In fields such as biosensing, analyte binding often relies on very specific molecular recognition interactions that nature has supplied, such as antibody-antigen interactions or strands of complimentary DNA forming double hefices. Unfortunately, because versatile and highly selective receptors for TNT or other explosive molecules are not available, chemists are left to rely on less specific interactions. 

Series of various mono,- bi-, and poly-(thio)urea-functionalized (poly)saccha-rides have already been synthesized and studied for molecular recognition of, e.g., dimethyl and phenylphosphate as model compounds for monoanionic and polyanionic phosphate esters, respechvely [111]. Thiourea derivatives such as 195-197 were analyhcally identified to provide double hydrogen bonding mediated host-guest complexes of well-defined dimension and orientations and were also reported to serve as phosphate binders even in the hydrogen bonding environment of water (Figure 6.57) [111]. 

Two of the most unique and appealing properties of DNA for molecular electronics are its double-strand recognition and a special structuring that suggests its use for self-assembly. 

Benichou, A., Aserin, A., Garti, N. (2002). Double emulsions stabilized by new molecular recognition hybrids of natural polymers. Polymers for Advanced Technologies, 13,1019-1031. 

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