Saccharide Recognition by Oligo（ meta-ethynylpyridine）s in Protic Media

Previously, we have reported tris（ethynylpyridine） macrocycles as synthetic receptors for ribofuranosides, deoxyribofuranosides, and glucopyranosides. consisted of “meta”-tethered ethynylpyridine trimers. The hydrogen-bonding skeletons of the macrocycles If the ethynylpyridine unit is polymerized, the resulting oligo-and poly（rneta-ethynylpyridine） s would adopt unfolded, somewhat zigzag conformations because each pyridine nitrogen is mainly located on opposite sides of the ethynediyl bonds to cancel the dipoles. When the polymer meets with a saccharide, its pseudolinear conformation may be guided to a well-ordered helical structure in order that the nitrogen atoms of the pyridine rings inwardly interact with peripheral saccharide-OH groups in a manner similar to those of the macrocycles （Fig. 1）. Thus, the chirality of saccharides added can be transferred to the helical sense of the polymer, depending on the stereochemistry of the saccharides.