Chiral helicity induced by hydrogen bonding and chirality of podand histidyl moieties

[GRAPHICS] The single-crystal X-ray structure determination of N,N ' -bis{(S)-(+)-1-methoxycarbonyl-2(4-imidazolyl)ethyl}-2,6-pyridinedicarboxamide (L-BHisPA) and the D-isomer (D-BHisPA) derived from the corresponding chiral histidine revealed a left- and right-handed helical conformation, respectively, through intramolecular hydrogen bonding and chirality of the podand histidyl moieties, Furthermore, each helical molecule is connected by continuous intermolecular hydrogen bonds to afford a left or right handed helical assembly, respectively, in the crystal packing.