10-Hydroxy-2-azapentacyclo[10.8.0.02,10.04,9.015,20]icosa-1(12),4(9),5,7,13,15(20),16,18-octaene-3,11-dione

In the title compound, C19H11NO3, the isoindolinone ring system is approximately planar with a maximum atomic deviation of 0.071 (1) angstrom and the five-membered ring of the dihydrobenzo[g]indol-3-one unit assumes an envelope conformation. The naphthalene ring system makes a dihedral angle of 39.47 (4)degrees with the mean plane of the isoindolinone system. Intermolecular O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonding helps to stabilize the crystal structure.