(2E)-3-(6-Chloro-2-methoxyquinolin-3-yl)-1-(2,4-dimethylquinolin-3-yl)prop-2-en-1-one

The molecule of the title compound, C24H19ClN2O2, is bent, with the dihedral angle between the terminal quinoline ring systems being 63.30 (5)°. The quinolinyl residues are connected by an almost planar prop-2-en-1-one bridge (r.m.s. deviation = 0.022 Å), with the dihedral angles between this plane and the appended quinolinyl residues being 75.86 (7) and 38.54 (7)°. The C atom of the methoxy group is close to coplanar with its attached ring [deviation = 0.116 (2) Å]. In the crystal, a three-dimensional architecture is constructed by methyl–carbonyl C—H⋯O interactions and π–π interactions between centrosymmetrically related quinolinyl residues [centroid-to-centroid separations 3.5341 (10) and 3.8719 (9) Å].


Comment
Quinoline derivatives are an important class of natural and synthetic products, which possess a number of interesting biological activities, are valuable intermediates in organic synthesis, and exhibit a multitude of photo-physical properties (Prasath & Bhavana, 2012;Joshi et al., 2011). Also, quinolinyl chalcones have gained much attention due to their bioactivity, such as anti-bacterial, anti-fungal, anti-malarial and anti-cancer activities (Prasath et al., 2013a). It was in this connection that the title compound, (I), was investigated.
The molecular structure of (I), Fig. 1, comprises two quinolinyl rings connected by the ends of a prop-2-en-1-one bridge. The dihedral angle between the quinolinyl rings is 63.30 (5)°. The methoxy group is coplanar with the quinolinyl ring to which it is attached, as seen in the value of the C24-O2-C16-N2 torsion angle of 3.1 (2)°. The conformation about the ethylene bond [C13═C14 = 1.335 (2) Å] is E. The central C 5 O plane comprising the O1, C8 and C12-C15 atoms, is almost planar, with an r.m.s. deviation of 0.022 Å. The N1-and N2-containing quinolinyl rings form dihedral angles of 75.86 (7) and 38.54 (7)°, respectively, with the central plane.

Experimental
A mixture of 2,4-dimethyl-3-acetylquinoline (200 mg, 0.001 M) and 2,6-dichloroquinoline-3-carbaldehyde (230 mg, 0.001 M) in methanol (20 ml) containing 0.2 g of potassium hydroxide was stirred at room temperature for 12 h. At the end of the period, the reaction mixture was neutralized with dilute acetic acid and the resultant solid was filtered, dried and purified by column chromatography using ethyl acetate-hexane (2:1) mixture to afford (I). Re-crystallization was by slow evaporation of an acetone solution of (I), which yielded pale-yellow blocks in 61% yield; M.pt: 423-425 K.

Figure 1
The molecular structure of (I), showing displacement ellipsoids at the 50% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.