β-Hairpin peptides containing 3-amino benzoic acid, a constrained γ-amino acid

3-[(E)-(2,4-Dichloro­pbenzyl­idene)amino]­benzoic acid

In the crystal of the title compound, C(14)H(9)Cl(2)NO(2), inversion-related dimers with R(2) (2)(8) ring motifs are formed by inter-molecular O-H⋯O hydrogen bonding. The 3-amino-benzoic acid group and the 2,4-dichlobenzaldehyde moiety subtend a dihedral angle of 55.10 (2)°. The H atom of the carboxyl group is disordered over two sites with equal occupancies.

(E)-3-[(2-Hy­droxy-3-meth­oxy­benzyl­idene)amino]­benzoic acid

In the title compound, C(15)H(13)NO(4), the dihedral angle between the substituted benzene rings is 9.9 (8)°. Part of the mol-ecule (the salicylaldimine segment) is disordered over two sets of sites, with a refined site-occupancy ratio of 0.550 (14):0.450 (14). Intra-molecular O-H⋯N hydrogen bonds form S(6) ring motifs. In the crystal, pairs of O-H⋯O hydrogen bonds link mol-ecules into centrosy...

(E)-3-[(3-Eth­oxy-2-hy­droxy­benzyl­idene)amino]­benzoic acid

In the title compound, C(16)H(15)NO(4), a potential bidentate N,O-donor Schiff base ligand, the benzene rings are inclined to one another by 4.24 (12)°. The mol-ecule has an E conformation about the C=N bond. An intra-molecular O-H⋯N hydrogen bond makes an S(6) ring motif. In the crystal, pairs of O-H⋯O hydrogen bonds link the mol-ecules, forming inversion dimers with R(2) (2)(8) ring motifs. T...

3-[(3-Oxo-1,3-dihydro­isobenzofuran-1-yl)amino]benzoic acid

In the title compound, C(15)H(11)NO(4), the dihedral angle formed by the benzene ring and isobenzofuran ring system is 67.82 (5) Å. The crystal structure is stabilized by inter-molecular O-H⋯O and N-H⋯O hydrogen-bonding inter-actions.

Peptides containing a D-amino acid from frogs and molluscs.