Helix-forming self-assembly of enantiopure 2,2 '-dimethylbiphenyl-6,6 '-dipropiolic acid and amide organized by hydrogen bonds

Single-crystal X-ray diffraction revealed that the molecules of both the ti tle compounds (S)-5 and (S)-6 are linked, via double hydrogen bonds, in inf inite chains which follow the crystallographic symmetry of the three- and f our-fold screw axis, respectively. To our knowledge this represents the fir st documented case when intermolecular carboxylic hydrogen bond constitutes an integral part of a helix backbone set up from repeating homochiral Subu nits. (C) 2001 Elsevier Science Ltd. All rights reserved.