The co-crystal 4,6-diacetylresorcinol–1-aminopyrene (2/1)

In the title molecular complex, the molecules form stacks consisting of aggregates with disordered 1-aminopyrene molecule surrounded by two 4,6-diacetylresorcinol molecules. Neighbouring stacks are linked by hydrogen bonds between the amine H atoms of the 1-aminopyrene molecule with the adjacent carbonyl oxygen atom of the 4,6-diacetylresorcinol molecule.


Chemical context
Co-crystals are crystalline single phase materials made up of molecules of two or more compounds. They are used in a variety of fields, including paper, textiles and the chemical, photographic, and electronic industries (Golbedaghi & Fausto, 2018). However, their main uses are centered in the pharmaceutical industry, where they have been gaining importance in recent years.
Schiff bases are the products of the condensation reaction of aldehydes or ketones with amines. They have multiple uses, for example as pigments and dyes, intermediates in organic synthesis, and as catalysts and polymer stabilizers. They also exhibit a broad range of biological activities. They play an important role in coordination chemistry as they readily form stable complexes with most transition metals (Aazam et al., 2006(Aazam et al., , 2008(Aazam et al., , 2010El-Attar & Aazam, 2021). In the process of the synthesis of such compounds with 4,6-diacetylresorcinol and 1-aminopyrene as the precursors, a new co-crystal, C 16 H 11 NÁ2C 10 H 10 O 4 , has been obtained.

Structural commentary
The formula unit of the title compound consists of two 4,6diacetylresorcinol molecules and one 1-aminopyrene molecule, which lies on an inversion center. Besides this, this molecule is further disordered so that the amino N atom is distributed over four chemically equivalent positions, at the C11 and C13 atoms, with the occupancies of 0.428 (2) and 0.072 (2) for N1 and N1B, respectively ( Fig. 1).
In the 4,6-diacetylresorcinol molecule, the hydroxy groups form intramolecular hydrogen bonds with the oxygen atoms of neighbouring acetyl groups, generating S(6) rings (Table 1).

Supramolecular features
In the crystal, the molecules form centrosymmetric aggregates with two molecules of 4,6-diacetylresorcinol positioned on both sides of the 1-aminopyrene molecule (Fig. 2). The mean planes of the aromatic rings of the 4,6-diacetylresorcinol molecules are inclined at 2.91 (10) to the mean plane of the tetracyclic core of the 1-aminopyrene molecule. A short intercentroid separation Cg1Á Á ÁCg2 of 3.492 (1) Å is observed in this aggregate, with Cg1 being the centroid of C3-C8 ring of diacetylresorcinol and Cg2 the centroid of one of the aminopyrene rings, C11-C18. These aggregates are packed into stacks bystacking interactions between 4,6-diacetylresorcinol molecules. Neighbouring stacks are linked by hydrogen bonds between the amino H atom of the 1-amino-pyrene molecule with the adjacent carbonyl oxygen atom of the 4,6-diacetylresorcinol molecule, thus forming a threedimensional network (Fig. 3).

Figure 2
A view of the crystal packing showing thestacking interactions.

Figure 3
The crystal packing of the title compound viewed along the b axis, showing the N-HÁ Á ÁO hydrogen bonds.

Figure 1
The asymmetric unit of the title compound with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.
benzoic acid and showed that the NH 2 groups can act as Hdonors in the intermolecular hydrogen-bonding interactions, as in the title compound. (Mandal et al., 2020, refcode BOYQOY;Mandal et al., 2019, refcode LORBOM).

Synthesis and crystallization
A solution of 1-aminopyrene (1 mmol, 0.233 g) dissolved in 10 ml of ethanol was added dropwise to 4,6-diacetylresorcinol (DAR) (0.5 mmol, 0.097 g) dissolved in 10 ml of ethanol, 3 drops of acetic acid were added, and the mixture was stirred for 15 min at room temperature and then for about 3 h under reflux. Yellow fiber-like crystals of the Schiff base ligand were separated. They were filtered off and washed with 4 ml of ethanol, weight = 0.021 g, yield = 7.12%, m.p. = 523 K, m/z = 592.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The C-N bond distances for the disordered N atom were restrained to be similar. The minor occupancy N1B atom was constrained to have the same ADPs as the C atom to which it is bonded. N-H bond distances were restrained to a target value of 0.88 (2) Å , and the H-N-H and C-N-H bond angles were restrained to be similar to each other. Subject to these conditions the occupancy rates refined to 0.428 (2) and 0.072 (2). O-bound H atoms were refined with U iso (H) = 1.5U eq (O). C-bound H atoms were positioned geometrically (C-H = 0.9-0.98 Å ) and refined as riding on their parent atoms with U iso (H) = 1.2-1.5U eq (C). The co-crystal 4,6-diacetylresorcinol-1-aminopyrene (2/1)

Computing details
Data collection: APEX4 (Bruker, 2021); cell refinement: SAINT (Bruker, 2021); data reduction: SAINT (Bruker, 2021); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2019/2 (Sheldrick, 2015b), ShelXle (Hübschle et al., 2011); software used to prepare material for publication: publCIF (Westrip, 2010). 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. The single nitrogen atom is disordered over four chemically equivalent positions (each two are also crystallographically equivalent, by inversion). The C-N bond distances were restrained to be similar. The minor N atom was constrained to have the same ADP as the C atom it is bonded to. The N-H bond distances were restrained to a target value of 0.88 (2) Angstrom, and the H-N-H and C-N-H bond angles were each restrained to be similar to each other. Subject to these conditions the occupancy rates refined to two times 0.428 (2) and two times 0.072 (2).