In the title solvated compound, C28H19N2O4·C2H6OS, the central β-lactam ring is almost planar (r.m.s. deviation = 0.002 Å). It makes dihedral angles of 1.92 (11), 83.23 (12) and 74.90 (10)° with the meth-oxy- and chloro-phenyl rings and the ring plane of the 1H-benzo[de]iso-quinoline-1,3(2H)-dione group [maximum deviation = 0.089 (1)], respectively. An intra-molecular C-H⋯O hydrogen bond closes an S(6) ring and helps to establish the near coplanarity of the β-lactam and meth-oxy-benzene rings. In the crystal, the components are linked by C-H⋯O hydrogen bonds, C-H⋯π inter-actions and aromatic π-π stacking inter-actions [centroid-to-centroid distances = 3.6166 (10) and 3.7159 (10) Å], resulting in a three-dimensional network, The dimethyl sulfoxide solvent mol-ecule is disordered over two sets of sites in a 0.847 (2):0.153 (2) ratio.
Keywords: 1H-benzo[de]isoquinoline-1,3(2H)-dione group; azetidin-2-ones; crystal structure; disorder; β-lactam ring.