Crystal structure of (E)-2-[(2-bromopyridin-3-yl)methylidene]-6-methoxy-3,4-dihydronaphthalen-1(2H)-one and 3-[(E)-(6-methoxy-1-oxo-1,2,3,4-tetrahydronaphthalen-2-ylidene)methyl]pyridin-2(1H)-one

The title compounds C17H14BrNO2 (I), and C17H15NO3 (II), were obtained from the reaction of 6-methoxy-3,4-dihydro-2H-naphthalen-1-one and 2-bromonicotinaldehyde in ethanol. Compound (I) was the expected product and compound (II) was the oxidation product from air exposure.

The title compounds C 17 H 14 BrNO 2 , (I), and C 17 H 15 NO 3 , (II), were obtained from the reaction of 6-methoxy-3,4-dihydro-2H-naphthalen-1-one and 2bromonicotinaldehyde in ethanol. Compound (I) was the expected product and compound (II) was the oxidation product from air exposure. In the crystal structure of compound (I), there are no short contacts or hydrogen bonds. The structure does displayinteractions between adjacent benzene rings and adjacent pyridyl rings. Compound (II) contains two independent molecules, A and B, in the asymmetric unit; both are non-planar, the dihedral angles between the methoxybenzene and 1H-pyridin-2-one mean planes being 35.07 (9) in A and 35.28 (9) in B. In each molecule, the 1H-pyridin-2-one unit participates in intermolecular N-HÁ Á ÁO hydrogen bonding to another molecule of the same type (A to A or B to B). The structure also displaysinteractions between the pyridyl and the benzene rings of non-equivalent molecules (viz., A to B and B to A).

Chemical context
In order to address the need for new therapeutic agents, medicinal chemists have often looked to nature for inspiration. Our research strategy to synthesize novel compounds considered analogs of the natural product chalcone, which contains two aromatic rings and an --unsaturated ketone. Chalcones, bioactive defense molecules found in plants and used in traditional Chinese medicine, have demonstrated anticancer, antibacterial, antifungal, and anti-inflammatory properties (Nowakowska, 2007;Katsori et al., 2011). Chalcones that contain methoxy groups (Shenvi et al., 2013;Bandgar et al., 2010) and/or pyridine groups (Prasad et al., 2008;Yee et al., 2005) have demonstrated activity against a variety of cancer cell lines and antibiotic-resistant bacteria. Thus, we set out to create a library of chalcones that combine those two functional groups. During the synthesis of the title compound (I) by the Claisen-Schmidt condensation of 6-methoxy-3,4-dihydro-2H-naphthalen-1-one and 2-bromonicotinaldehyde, two different types of crystals were obtained -those of the desired chalcone (I) and those of the oxidized product (II). The title compound (I) is a chalcone analog of one currently being studied for its potential anticancer and antibacterial activity [unpublished results]. ISSN 2056-9890
In each one of the independent molecules in (II), the 1Hpyridin-2-one unit participates in intermolecular N-HÁ Á ÁO hydrogen bonding, with a classical R 2 2 (8) synthon, to another molecule of the same type (A to A or B to B), see Fig. 5  A view of the molecular structure of compound (I), showing the atom and ring labeling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A view of the molecular structure of compound (II), showing the atom and ring labeling. Displacement ellipsoids are drawn at the 50% probability level.

Database survey
A search of the Cambridge Structural Database (Version 5.37 with four updates, Groom et al., 2016) for structures containing the combined tetralone and pyridine backbone returned no hits. The search was broadened by changing the nitrogen to carbon, which returned 43 hits. The carboncontaining version of (I) has been reported (Dimmock et al., 2002;Yee et al., 2005). Many of these similar chalcones also demonstrated biological activities (Dimmock et al., 2002).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were positioned geometrically and refined as riding with C-H = 0.95 or 0.98 Å and U iso (H) = 1.2U eq (C). The hydrogen-bonded units in (II) are linked bystacking interactions between the phenyl and pyridyl rings in adjacent molecules of different type.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x (7)      Special details Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 sigma(F 2 ) is used only for calculating Rfactor (gt).