4-[(4-Chloro-phen-yl)(hy-droxy)methyl-idene]isochromane-1,3-dione.

In the title compound, C(16)H(9)ClO(4), the six-membered heterocyclic ring adopts a screw-boat conformation. The benzene rings are oriented to each other at a dihedral angle of 59.26 (9)°. The mol-ecular structure exhibits a ring motif, viz. S(6), owing to an intra-molecular O-H⋯O hydrogen bond. The presence of C-H⋯O contacts generates an infinite chain along [001]. Also present are π-π stacking inter-actions between neighbouring isochromanedione benzene rings [centroid-centroid distance = 3.746 (1) Å], and C-O⋯π inter-actions [O⋯centroid = 3.934 (2) Å].