Well‐defined secondary structures

Abstract

Molecules and assemblies of molecules with well-defined secondary structures have been designed and characterized by controlling noncovalent interactions. By specifying intermolecular interactions, a class of information-storing molecular duplexes have been successfully developed. These H-bonded molecular duplexes demonstrate programmable, sequence-specificity and predictable, tunable stabilities. Based on these highly specific molecular zippers (or glues), a systematic approach to designing self-assembled structures is now feasible. Duplex-directed formation of b-sheets, block copolymers and templated organic reactions have been realized. By specifying intramolecular noncovalent interactions, a backbone-rigidification strategy has been established, leading to unnatural molecular strands that adopt well-defined, crescent or helical conformations. The generality of this backbone-rigidification strategy has been demonstrated in three different classes of unnatural oligomers: oligoaramides, oligoureas and oligo(phenylene ethynylenes). Large nanosized cavities have been created based on the folding of these helical foldamers. Tuning the size of the nanocavities has been achieved without changing the underlying helical topology. These helical foldamers can serve as novel platforms for the systematic design of nanostructures.

Handedness control of peptide helices by amino acid side‐chain chirality: Ile/aIle peptides

“…Foldamers (oligomers with strong folding propensities), including peptides, represent a modern area of growing interest for fundamental and applied research activities because such compounds offer unique scaffolds for the development of molecular functions 60–62. However, the configurational factors controlling details of their 3D‐properties, e.g., chirality of the side chain of the constituent monomeric unit, are, in general, still poorly understood.…”

Intramolecular hydrogen bond directed stable conformations of benzoyl phenyl oxalamides: unambiguous evidence from extensive NMR studies and DFT-based computations

“…[6][7][8] Nevertheless ]O/H-O type hydrogen bonds, which are stronger than the other two have also been observed in b-dicarbonyl compounds. It is generally noticed that nearly 30% of the drugs available on the market possess at least one uorine atom and such organic uorine-containing molecules have applications in molecular imaging, 9,10 crystal engineering, [11][12][13] biomaterials and agrochemicals.…”

Organic fluorine involved intramolecular hydrogen bonds in the derivatives of imides: NMR evidence corroborated by DFT based theoretical calculations

“…1-4 The importance of HB in the self-assembly of molecules [5][6][7][8][9][10][11][12][13][14][15][16][17] is well documented in the literature. The majority of the reported intramolecular HB mainly pertains to motifs of the type O···H-N and N···H-N [18][19][20][21][22] . Furthermore it is well known that nearly 30% of the commercially available drug molecules contain at least one fluorine atom.…”