1,4-Bis(4-methoxyphenyl)naphthalene

Two independent molecules comprise the asymmetric unit of the title naphthalene derivative, which exhibit very similar conformations. The pendant 4-methyoxybenzene rings are splayed out of the plane through the naphthalene ring system.

In the crystal, C-HÁ Á Á interactions, Table 1, link molecules into a supramolecular chain along the b-axis direction, i.e. with a helical topology. The chains assemble in the crystal without directional interactions between them.

Synthesis and crystallization
Tetrathiafulvalene [2-(1,3-dithiolan-2-ylidene)-2H-1,3-dithiole; 0.204 g, 1.0 mmol] was added to a solution of 1,3-bis(4methoxyphenyl)isobenzofuran (0.33 g, 1.0 mmol) in dry xylenes (15 ml). The solution was refluxed until the benzo[c]furan was consumed, i.e. after ca 6 h, as indicated by the disappearance of fluorescence from the solution. After removal of xylenes in vacuo, the crude product was dissolved in dry dichloromethane (DCM, 15 ml) and kept at 273 K. To this solution, triflic acid (0.075 g, 0.50 mmol) was added followed by stirring at room temperature for 10 min. After the completion of reaction (as monitored by TLC), the solution was poured into ice-water (20 ml) and then extracted with DCM (2 Â 10 ml). The combined organic layer was washed with aq. NaHCO 3 (2 Â 10 ml) and then dried over Na 2 SO 4 .
The removal of solvent was followed by column chromatographic purification (silica gel, 10% ethyl acetate in hexane) to afford 1,4-bis(4-methoxyphenyl)naphthalene (0.288 g, 85%) as a yellow solid. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of an ethyl acetate solution of the compound held at room temperature; m.p. 421-423 K.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Table 1 Hydrogen-bond geometry (Å , ).

Figure 1
The molecular structures of the title compound showing atom-numbering scheme and displacement ellipsoids at the 30% probability level. The H atoms are shown as spheres of arbitrary radius.

Figure 2
An overlay diagram of the first (red image) and inverted-second (black) independent molecules of the title compound.

data-1
IUCrData (2020). 5, x200212 full crystallographic data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.28 e Å −3 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-2
IUCrData (2020). 5, x200212 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. The C-bound H-atoms were included in calculated positions and treated as riding with C-H = 0.93-0.96 Å, and with U iso (H) = 1.5U eq (C-methyl) and 1.2U eq (C) for the other H-atoms.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )