Diamines molecular recognition

Ermer, O., Eling, A., Molecular recognition among alcohols and amines - super-tetrahedral crystal architectures of linear diphenol-diamine complexes and aminophenolse. J. Chem. Soc., Perkin Trans. 21994, 925-944. 

A different H-bonding network was obtained with 1,1,3,3-tetraphenyldisilox-ane-l,3-diol (24) [20]. In the molecular recognition process with hexamethylenetetramine (25), the diol acts as a double donor and the diamine as a double... 

Unlike the complex 39 36, the complex 39 40, formed with the mismatched diol, consists of a vastly interlinked layered H-bonded network that is in part reminiscent of the crystal structure previously observed for (R,R)-trans- 1,2-diaminocyclo-hexane and mexo-l,2-cyclohexanediol (Figure 47, Scheme 17). The efficiency of 39 to recognize the mismatched diol suggests that acyclic diamines are the optimal candidates for the molecular recognition of sterically demanding diols with respect to the cyclic diamines. In fact, (i ,i )-tra x-l,2-diaminocyclohexane did not recognize mismatched 39 40. 

Clavier et al. used the amino acid (L)-valine to synthesise a C-chiral imdazolidinium salt for chiral molecular recognition studies [65]. The synthetic route utilises the C-terminus to form an amide. Subsequent reduction to the diamine and ring closure with trimethyl-orthoformate yields the chiral imdazolidinium salt (see Figure 6.25). 

Hanessian, S., Gomtsyan, A., Simard, M., and Roelens, S., Molecular recognition and self-assembly by weak hydrogen bonding Unprecedented supramolecular helicate structures from diamine/diol motifs, J. Am. Chem. Soc. 116, 4495 496 (1994). 

Bearing this in mind, we designed and synthesized a number of P-CD derivatives [27-34] which could i) bind copper(II) forming a multisite recognition system ii) show thermodynamic stereoselectivity in copper(II) ternary complexes iii) perform chiral separation of unmodified amino acid enantiomers. Among the monofunctionalized P-CD derivatives, only those functionalized in position 6 with diamines show chiral molecular recognition [29,32,35-37]. On the contrary, the P-CDs both functionalized in position 3 and those where a triamine was attached to the narrower rim of the toroid do not act as chiral receptors. 2-(aminomethyl)pyridine, histamine and NH3 molecules were used to obtain the three isomers of P-CDs (Figure 3), but only the A,BCD-NH2 molecule, coordinated to the copper(II) ion, is seen to have enatioselective effects on aromatic amino acids [38]. 

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