(2E,2′E)-1,1′-([1,1′-Biphenyl]-4,4′-diyl)bis[3-(dimethylamino)prop-2-en-1-one]

The π-conjugated planar title molecules are assembled through C—H⋯π interactions between neighboring molecules, resulting in stacking along the c-axis.


Structure description
�-Ketoamines are important not only for various chemical reactions, but also for creating functional complexes (Pettinari et al., 2014).Recently, they have also been used as reagents for covalent organic frameworks (Zhao et al., 2023).In this work, the crystal structure of the title �-ketoamine was determined.The molecule is almost flat, but the phenyl rings are tilted [dihedral angle = 30.14(8) � ] (Fig. 1) as a result of the repulsion between H atoms on the phenyl rings and intermolecular interactions, i.e., C-H� � ��, with neighboring molecules (Table 1).In addition to the carbonyl and the allyl groups, the amino groups also show a planar character, indicating the sp 2 character of the N atoms and the �-conjugated character of these functional groups.The bond-angle sums for both N atoms are 360.0� .
In the crystal, the molecules are assembled to form a two-dimensional layer-like structure in the (105) plane (Fig. 2).The molecules are stacked perpendicular to this plane through C-H� � �� interactions.Each molecule interacts with three neighboring molecules.Two different phenyl groups on the molecule accept the C donors (C21 and C22), resulting in additional C-H� � �� interactions (Tsuzuki et al., 2000) with molecules above and below (Fig. 3).The C21 methyl group on one side interacts with the phenyl ring of the stacked molecule above through a C21-H21� � �Cg2 interaction [C21� � �Cg2 = 3.538 (2) A ˚], while the C22 methyl group on the other side similarly interacts with the molecule below [C22� � �Cg1 = 3.608 (2) A ˚] where Cg1 and Cg2 are the centroids of the C1/C9/C17/C4/C18/C15 and C3/C14/C11/C7/C6/C16 rings, respectively.The distances between the phenyl groups are not remarkably short with centroid-centroid separations of 4.363 (1) and 4.833 (1) A ˚, and no obvious �-� interactions occur with neighboring molecules, indicating that the molecules are assembled mainly through C-H� � �� interactions.C-H� � �O interactions involving H22 and H22B (Table 1) also occur, which also contribute to assemble the molecules.

Synthesis and crystallization
A mixture of 4,4 0 -diacetyl biphenyl (0.953 g, 4.00 mmol), anhydrous DMF (12 ml), and N,N-dimethylformamide diethyl acetal (12 ml) was stirred and heated at 90 � C under a nitrogen atmosphere for 12 h.After cooling, diethyl ether (20 ml) was added slowly to the reaction mixture, resulting in a yellow powder.The precipitate was collected by suction filtration and it was then immersed in n-pentane for 4 h at room temperature.After that, the precipitate was collected by suction filtration and dried under vacuum at 170 � C overnight (0.961 g, 1.98 mmol, yield 50%). Crystals of the title compound were obtained by recrystallization through slow evaporation of a methanol solution.After several days, yellow crystals were obtained.

Refinement
Details of crystal data, data collections, and structure refinements are shown in Table 2.

Figure 1
Illustration of the title molecule, composed of crystallographically independent atoms with displacement ellipsoids drawn at the 50% probability level.

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.

data reports data-2
IUCrData (2024).9, x240358 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.All hydrogen atoms were fixed geometrically and refined using a riding-model approximation with C-H = 0.95 (for phenyl and allyl) and 0.98 (for methyl) Å.

Figure 2
Figure 2Packing structure of the title compound along the b axis.

Table 2
Experimental details.