view article

Figure 9
Topological presentation of the close packing of cis-alicyclic β-amino acids (a) and the results of the type of rotation 8 → 9 in one (b) and two dimensions (c). Since β-amino acids are zwitterions, their symbolic presentation denotes the NH3+ group with a small triangle rotated through 180° to that of NH2 groups in carboxamides, depicted in Fig. 3[link](b), while the COO moiety is denoted by two small circles. The molecules forming helices are linked by two NH⋯O hydrogen bonds along the twofold screw axes. They enclose symmetry-free R22(8) dimers. The enantiomeric helices are cross-linked by the third N—H⋯O hydrogen bond, simultaneously enclosing the R44(12) and R42(8) tetramers.

ISSN: 2052-5206
Follow Acta Cryst. B
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds