5-Amino-1-naphthol: two-dimensional sheets built up from R(4)(4)(18) rings formed by O-H...N, N-H...O and pi-pi interactions.

The crystal structure of the title compound, C(10)H(9)NO, (I), contains intermolecular O-H...N and N-H...O hydrogen bonds which together form sheets parallel to the (001) plane containing rings with an unusual R(4)(4)(18) motif. These rings are additionally stabilized by an intermolecular pi-pi stacking interaction. The significance of this study lies in the comparison drawn between the molecular structure of (I) and those of related compounds (1,5-diaminonaphthalene, 8-amino-2-naphthol, 3-amino-2-naphthol and aniline), which shows a close similarity in the noncoplanar orientation of the amine group and the aromatic moiety. Comparison of the crystal structures of (I) and several of its simple analogues (1-naphthol, naphthalene-1,4-diol, naphthalene-1,5-diol and 4-chloro-1-naphthol) shows a close similarity in the packing of the molecules, which form pi-stacks along the shortest crystallographic axes with a substantial spatial overlap between adjacent molecules.