Crystal structure of 1,1′-{(1E,1′E)-[4,4′-(9H-fluorene-9,9-diyl)bis(4,1-phenylene)]bis(azanylylidene)bis(methanylylidene)}bis(naphthalen-2-ol) dichlorobenzene monosolvate

A novel bis(anil) compound was synthesized and structurally characterized. Theoretical calculations suggested that the new bis(hydroxyimine) will exhibit histone deacetylase SIRT2, histone deacetylase class III and histone deacetylase SIRT1 activities, and will act as inhibitor to aspulvinone dimethylallyltransferase, dehydro-l-gulonate decarboxylase and glutathione thiolesterase.

The bis(anil) molecule of the title compound, C 47 H 32 N 2 O 2 ÁC 6 H 4 Cl 2 , contains two anil fragments in the enol-enol form, exhibiting intramolecular O-HÁ Á ÁN hydrogen bonds. The two hydroxynaphthalene ring systems are approximately parallel to each other with a dihedral angle of 4.67 (8) between them, and each ring system makes a large dihedral angle [55.11 (11) and 48.50 (10) ] with the adjacent benzene ring. In the crystal, the bis(anil) molecules form an inversion dimer by a pair of weak C-HÁ Á ÁO interactions. The dimers arrange in a onedimensional column along the b axis via another C-HÁ Á ÁO interaction and a stacking interaction between the hydroxynaphthalene ring system with a centroid-centroid distance of 3.6562 (16) Å . The solvent 1,2-dichlorobenzene molecules are located between the dimers and bind neighbouring columns by weak C-HÁ Á ÁCl interactions. Theoretical prediction of potential biological activities was performed, which suggested that the title anil compound can exhibit histone deacetylase SIRT2, histone deacetylase class III and histone deacetylase SIRT1 activities, and will act as inhibitor to aspulvinone dimethylallyltransferase, dehydro-l-gulonate decarboxylase and glutathione thiolesterase.

Structural commentary
In the title bis(anil) molecule, two hydroxynaphthalene ring systems are approximately parallel to each other with a dihedral angle of 4.67 (8) between them (Fig. 1). The 9Hfluorene ring system (C1-C13) forms large dihedral angles of 78.80 (10) and 61.41 (9) , respectively, with the benzene C14-C19 and C31-C36 rings. Each hydroxynaphthalene ring system also forms a large dihedral angle with the adjacent benzene ring [55.11 (11) between the C21-C30 ring system and the C14-C19 ring, and 48.50 (10) between the C38-C47 ring system and the C31-C36 ring]. Both fragments of the hydroxynaphthalene Schiff bases are in the enol form, forming intramolecular O-HÁ Á ÁN hydrogen bonds (Table 1).

Supramolecular features
In the crystal, the bis(anil) molecules form an inversion dimer via a pair of weak C-HÁ Á ÁO interactions (C3-H3Á Á ÁO1 i ; symmetry code given in Table 1). The dimers form a 1D column along the b axis through a C-HÁ Á ÁO (C35-H35Á Á ÁO1 ii ; Table 1) and astacking interaction between the hydroxyl naphthalene ring systems with a centroidcentroid distance of 3.6562 (16) Å (Cg1Á Á ÁCg2 ii ; Cg1 and Cg2 are the centroids of C21-C30 and C38-C47 ring systems, respectively). Dichlorobenzene molecules are located between the dimers and bind the neighboring columns by weak C-HÁ Á ÁCl interactions (Table 1 and Fig. 2).

Refinement
Crystal data, details of data collection, and results of structure refinement are summarized in Table 2. All C-bound H atoms were placed in calculated positions (C-H = 0.95 Å ) and refined using a riding model [U iso (H) = 1.2U eq (C)], while the H atoms of the OH groups were localized in a difference-Fourier map and refined with U iso (H) = 1.5U eq (O).

Computing details
Data collection: APEX3 (Bruker, 2018); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009). 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.