Santal monohydrate, an isoflavone isolated from Wye-thia mollis.

THE TITLE COMPOUND [SYSTEMATIC NAME: 3-(3,4-di-hydroxy-phen-yl)-5-hy-droxy-7-meth-oxy-4H-chromen-4-one monohydrate], C16H12O6·H2O, is a monohydrate of a natural product santal isolated from Wye-thia mollis. In the santal mol-ecule, the dihedral angle between the benzo-quinone and di-hydroxy-phenyl fragments is 53.9 (1)° and an intra-molecular O-H⋯O hydrogen bond occurs. In the crystal, O-H⋯O hydrogen bonds link the components into corrugated layers parallel to the ac plane. The short distance of 3.474 (5) Å between the centroids of the benzene rings in neighbouring santal mol-ecules reveals then existence of π-π inter-actions within the layers.