Molecular recognition preorganization

Preorganization principle, 26 772 Preorganization/reorganization, in molecular recognition, 26 770-774 Preparation centrifuge, operation, 5 529-530... 

Figure 7.1.4. The scheme of formation of [2.2.2]cryptand. marked the start of molecular recognition studies. As described in Chapters 2 and 3, the Pedersen analysis was later extended by Lehn s studies of the complementarity of sizes and shapes ofthe cryptand cavities and their guests, and by Cram s preorganization studies. In general, crown ethers and cryptands exhibit analogous complexation behaviour. Thus, similarly to the former host molecules, cryptands in the free, uncomplexed state elongate the vacant cavity by rotating a methylene group inward. Thus, the N...N distance in [2.2.2]-cryptand 54 across the cavity is extended to almost 70 pm [18] whilst, in the complexed...

Supramolecular chemistry has first relied on the development of preorganized molecular receptors for effecting molecular recognition, catalysis, and transport processes on the basis of the molecular information stored in the covalent framework of the components and processed at the supramolecular level through specific interactional algorithms. 

Cram, Donald James. (1919-2001). Awarded the Nobel Prize for chemistry, together with Lehn, in 1987 for work in elucidating mechanisms of molecular recognition, which are fundamental to enzymic catalysis, regulation, and transport. Cram also studied three-dimensional cyclic compounds that maintained a rigid structure, accepting substrates in a structurally preorganized cavity. He called these compounds cavitands, while Lehn named them cryptands. Cram was awarded a doctorate by Harvard University in 1947. 

N-Hydroxy peptides, peptides with N -hydroxy moieties. The hydroxamate groups in such pseudopeptides may act as metal coordination sites in order to preorganize peptide structures. The N -hydroxy group confers different hydrogen bonding capabilities compared to native peptides, thus modifying the conformation and potentially also molecular recognition [J. Lawrence et al., Org. Biomol. Chem. 2006, 4, 3125]. 

Figure 6. Relationships between complementarity and molecular recognition and between constraint and preorganization...

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