In the title mol-ecule, C(24)H(18)INO(6)S, the heterocyclic thia-zine ring adopts a half-chair conformation, with the S and N atoms displaced by 0.381 (5) and -0.449 (5) Å, respectively, from the plane formed by the remaining atoms in the ring; the puckering parameters are Q = 0.550 (2) Å, θ = 61.7 (2)° and ϕ = 31.4 (3)°. The conformation is stabilized by an intra-molecular O-H⋯O hydrogen bond. The two nonfused benzene rings lie almost parallel to each other [dihedral angle = 9.18 (4)°], with a separation of 3.754 (2) Å between the centres of gravity of the two rings, indicating strong π-π inter-actions.