The asymmetric unit of the title compound, C19H16O3, contains three independent conformers. Each of the three conformers has essentially the same feature of non-coplanar aromatic rings whereby the aroyl group at the 1-position of the naphthalene ring is twisted in a perpendicular manner to the naphthalene ring. The dihedral angles between the benzene ring planes and the naphthalene ring systems are 75.34 (7), 86.47 (7) and 76.55 (6)° in the three conformers. The crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonds.

Key indicators: single-crystal X-ray study; T = 193 K; mean (C-C) = 0.002 Å; R factor = 0.036; wR factor = 0.099; data-to-parameter ratio = 13.6.In the title molecule {systematic name: [2,7-dimethoxy-8-(4-phenoxybenzoyl)naphthalen-1-yl](4-phenoxyphenyl)methanone}, C 38 H 28 O 6 , the 4-phenoxybenzoyl units adopt a syn orientation with respect to the naphthalene ring system. The internal benzene rings, A and B, make dihedral angles of 86.72 (5) and 79.22 (5) with the naphthalene ring system. The two terminal benzene rings, C and D, of the 4-phenoxybenzoyl groups are twisted with respect to benzene rings A and B, with dihedral angles of A/C = 62.72 (8) and B/D = 87.61 (6) . In the crystal, H atoms in the naphthalene system make two types of intermolecular C-HÁ Á ÁO interactions with the carbonyl O atom and the phenyl etheral O atom of neighbouring molecules. Molecules are further linked by C-HÁ Á Á interactions involving a H atom of terminal benzene ring D and the -system of the internal benzene ring A, forming dimers centered about an inversion center. Related literature

Poly(arylene ether ketone)s composed of a 1,8-diaroylenenaphthalene moiety, which is a non-coplanar accumulated aromaticring unit, were successfully synthesized through the nucleophilic aromatic substitution polycondensation of 1,8-bis (4-fluorobenzoyl)-2,7-dimethoxynaphthalene with several arene diols under mild conditions. The polymers show high glass transition temperatures (T g), poor solubility and good film-forming ability through heat casting.

In the title compound, C21H18O5, the dihedral angle between the naphthalene ring system and the benzene ring is 86.65 (6)°. The bridging carbonyl C—C(=O)—C plane makes dihedral angles of 83.57 (7) and 20.21 (8)°, respectively, with the naphthalene ring system and the benzene ring. The ester O—C=O plane and the benzene ring are almost coplanar, making a dihedral angle of 3.81 (18)°. The two meth­oxy groups lie essentially in the naphthalene ring plane [C—O—C—C torsion angles = 2.1 (2) and −1.44 (19)°]. In the crystal structure, a centrosymmetric dimer is formed through C—H⋯O bonds connecting the 7-meth­oxy group and the carbonyl O atom of the ester group. The dimers are further linked by C—H⋯O hydrogen bonds between the methoxy­carbonyl group and the bridging carbonyl O atom.

The entire title mol­ecule, C42H36O6, is completed by the application of a twofold axis. The 4-phen­oxy­benzoyl groups at the 1- and 8-positions of the naphthalene ring system are aligned almost anti­parallel. The dihedral angle between the best planes of the benzene rings of the benzoyl moieties and the naphthalene ring system is 70.52 (5)° and that between the best planes of the benzene rings of the phen­oxy groups and the naphthalene ring system is 27.80 (6)°. In the crystal, mol­ecules are linked into a three-dimensional architecture by C—H⋯O and C—H⋯π inter­actions.