Crystal structure and Hirshfeld surface analysis of 2-hydroxy-7-methoxy-1,8-bis(2,4,6-trichlorobenzoyl)naphthalene

The title compound has a non-coplanar accumulated aromatic rings structure. In the molecule, the two carbonyl groups are oriented in the same direction with respect to the naphthalene ring system and are situated roughly parallel to each other, whereas the two 2,4,6-trichlorobenzene rings are orientated in opposite directions with respect to the naphthalene ring system.


Chemical context
o-Hydroxyaryl ketones are generally recognized to be important precursors in the preparation of valuable products such as drugs, cosmetics, dyes and pesticides (Choy & Kwong, 2013;Naeimi et al., 2014;Nimnual et al., 2015). The preparation methods reported include, for example, Fries rearrangement of phenolic esters (Murashige et al., 2011), acylation of benzoquinone and derivatives (Schiel et al., 2001), coupling reactions of nitriles with boronic acids (Zhou & Larock, 2004), direct C-H bond arylation of 2-hydroxybenzaldehydes (Lee & Yi, 2015;Weng et al., 2010), and microwave-assisted direct benzoylation of phenols under solvent-free or ionic liquid conditions (Tran et al., 2017). The neighbouring carbonyl and hydroxy groups contribute to the regio-and chemoselectivities in these reactions. Conformational studies of hydroxyaryl ketones in the solid state and in solution have attracted considerable interest (Siskos et al., 2015;Nonhebel, 1968). Since the discovery of an effective method for diaroylation at the 1,8(peri)-positions of the naphthalene ring core and the related reactions (Okamoto & Yonezawa, 2009;Okamoto et al., 2011;Okamoto, Mitsui et al., 2012), we have reported on the spatial organization of 1,8-diaroylated naphthalenes and homologous compounds in both the solid state and solution Yoshiwaka et al., 2015;Okamoto et al., 2015;Ohisa et al., 2018). In the crystal structures of these compounds, which have non-coplanar accumulated aromatic rings, molecules are arranged by weak intermolecular interactions, such as non-classical hydrogen bonds and van der Waals interactions. Thus, the accumulation structures of 1,8-diaroylated naphthalenes are drastically changed by simple molecular modifications. Herein, we report on the crystal structure and Hirshfeld surface analysis of the title hydroxyaryl ketone, 2-hydroxy-7-methoxy-1,8-bis(2,4,6trichlorobenzoyl)naphthalene.

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. This compound consists of a naphthalene ring core with two 2,4,6-trichlorobenzoyl groups at the 1,8-positions, a hydroxy group at the 2-position, and a methoxy group at the 7-position of the naphthalene ring system, affording an unsymmetrical molecular structure.

Figure 1
The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Hirshfeld surface analysis and two-dimensional fingerprint plots
The Hirshfeld surface analysis (Spackman & Jayatilaka, 2009) and the associated two-dimensional fingerprint plots (McKinnon et al., 2007) were performed with Crystal-Explorer17 (Turner et al., 2017). The Hirshfeld surfaces are colour-mapped with the normalized contact distance, d norm , from red (distances shorter than the sum of the van der Waals radii) through white to blue (distances longer than the sum of the van der Waals radii). The Hirshfeld surface of the title compound mapped over d norm in the range À0.0895 to 1.1549 a.u., is shown in Fig. 4. The red points represent close contacts and negative d norm values on the surface. The largest red point corresponds to the short contact of 3.078 (3) Å involving the carbonyl O atom, O1, and carbon atom C23 i [symmetry code: (i) x, Ày + 3 2 , z À 1 2 ], while the other red points around the naphthalene ring indicate short ClÁ Á ÁH interactions.
The two-dimensional fingerprint plots from the Hirshfeld surface analysis are shown in Fig The Hirshfeld surface of the title compound mapped over d norm , in the range À0.0895 to 1.1549 a.u.   (3.9%), CÁ Á ÁC (3.0%) and OÁ Á ÁC/CÁ Á ÁO (1.3%) contacts also make significant contributions to the Hirshfeld surface.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All of the H atoms were found in a difference-Fourier map and were subsequently refined as riding atoms, with C-H = 0.95 (aromatic) and 0.96 (methyl) Å , and with U iso (H) = 1.2U eq (C).

Funding information
This work was partially supported by a Tokyo Ohka Foundation for The Promotion of Science and Technology Research Promotion Grant. Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: PROCESS-AUTO (Rigaku, 1998); program(s) used to solve structure: SIR2004 (Burla et al., 2007); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008). Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.00166 (17) Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.