Stabilization of chiral helices for saccharide-linked ethynylpyridine oligomers possessing a conformationally well-defined linkage

Tetrameric and octameric 2,6-pyridylene ethynylene oligomers linked to a β-D-glucopyranoside template through an o-phenylene linker were prepared and studied for their higher-order structure. These oligomers formed chiral helical structures through intramolecular hydrogen bonding between the ethynylpyridine moiety and the glucoside template. The rigidity of the o-phenylene linker stabilizes the helical structure to improve its CD activity and resistance against protic surroundings. Furthermore, the helical stabilization was enhanced by the addition of Cu(OTf)₂ and Zn(NO ₃)₂ salts. Tetrameric and octameric 2,6-pyridylene ethynylene oligomers joined to a β-D-glucopyranoside by a o-phenylene linker were prepared and their higher-order structure studied. The chiral helical structures formed by intramolecular H-bonding and linker stabilization improve CD activity and resistance to protic surroundings. Stabilization was enhanced with the addition of Cu(OTf)₂ and Zn(NO₃) ₂ salts.