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An alanine-based bilateral building block, linked by 2,5-thiophenediamide motifs and equipped with C-terminal 4-iodoaniline groups, was designed, allowing a noncovalent interaction network consisting of intramolecular chalcogen bonds and intermolecular halogen/hydrogen bonds, which cooperatively maintain a supramolecular β-sheet organization in the solid state, as well as in dilute CH3CN solution with a high g factor of −0.017. [ABSTRACT FROM AUTHOR]

Spontaneous resolution leading to conglomerate crystals remains a significant challenge. Here we propose the formation of orthogonal homochiral supramolecular helices in at least two dimensions to allow spontaneous resolution. We suggest the design rationale that the chiral species is made into helical building blocks to allow the helix formation. As a proof‐of‐concept, acetylalanine was made into a helical short azapeptide, its N‐amidothiourea derivative containing a β‐turn structure, to which a halogen atom was further introduced at the phenylthiourea aromatic ring. The resultant folded species undergoes both intermolecular hydrogen and halogen bonding across the turn structure to form orthogonal intermolecular hydrogen‐bonded and halogen‐bonded supramolecular helices in two dimensions, and undergoes chiral resolution upon crystallization. Meanwhile, counterparts containing either an F‐substituent with weak halogen bonding or no halogen atom crystallize as racemic compounds. [ABSTRACT FROM AUTHOR]

Spontaneous resolution leading to conglomerate crystals remains a significant challenge. Here we propose the formation of orthogonal homochiral supramolecular helices in at least two dimensions to allow spontaneous resolution. We suggest the design rationale that the chiral species is made into helical building blocks to allow the helix formation. As a proof‐of‐concept, acetylalanine was made into a helical short azapeptide, its N‐amidothiourea derivative containing a β‐turn structure, to which a halogen atom was further introduced at the phenylthiourea aromatic ring. The resultant folded species undergoes both intermolecular hydrogen and halogen bonding across the turn structure to form orthogonal intermolecular hydrogen‐bonded and halogen‐bonded supramolecular helices in two dimensions, and undergoes chiral resolution upon crystallization. Meanwhile, counterparts containing either an F‐substituent with weak halogen bonding or no halogen atom crystallize as racemic compounds. [ABSTRACT FROM AUTHOR]

We propose to employ intramolecular chalcogen bonding to make a helical building block take its otherwise unfavorable cis-conformation. The 2,5-thiophenediamide motif was taken to bridge two β-turn structures to lead to an azapeptide that exists in cis-conformation and forms a halogen-bonded single-strand helix that exhibits a much stronger supramolecular helicity and a higher thermal stability. [ABSTRACT FROM AUTHOR]

Supramolecular helices from helical building blocks represent an emerging analogue of the α-helix. In cases where the helicity of the helical building block is well propagated, the head-to-tail intermolecular interactions that lead to the helix could be enhanced to promote the formation and the stability of the supramolecular helix, wherein homochiral elongation dominates and functional helical channel structures could also be generated. This feature article outlines the supramolecular helices built from helical building blocks, i.e., helical aromatic foldamers and helical short peptides that are held together by intermolecular π–π stacking, hydrogen/halogen/chalcogen bonding, metal coordination, dynamic covalent bonding and solvophobic interactions, with emphasis on the influence of efficient propagation of helicity during assembly, favouring homochirality and channel functions. [ABSTRACT FROM AUTHOR]

We report supramolecular helical assembly in water of β-turn structured bis(N-amidothioureas) containing Br-substitutes of moderate halogen bonding ability, promoted by stronger hydrophobic interaction. The helical polymers show an unusual negative nonlinear CD-ee dependence. [ABSTRACT FROM AUTHOR]