2,2′-[2,5-Bis(hexyloxy)-1,4-phenylene]dithiophene

The asymmetric unit of the title compound, C26H34O2S2, comprises one half-molecule located on an inversion centre. The thiophene groups are twisted relative to the benzene ring, making a dihedral angle of 5.30 (7)°, and the n-hexyl groups are in a fully extended conformation. In the crystal, there are short C—H⋯π contacts involving the thiophene groups.

The asymmetric unit of the title compound, C 26 H 34 O 2 S 2 , comprises one half-molecule located on an inversion centre. The thiophene groups are twisted relative to the benzene ring, making a dihedral angle of 5.30 (7) , and the n-hexyl groups are in a fully extended conformation. In the crystal, there are short C-HÁ Á Á contacts involving the thiophene groups.

Comment
Thiophene-phenylene-thiophene unit, as in the title compound, is an interesting material to produce soluble electroluminescent materials for LED applications (Bouachrine et al., 2002) and making photovoltaic devices (Carle et al., 2010). The solubility characteristic for the title compound in organic solvents was enhanced by the presence of dialkyloxy groups on the phenylene fragment.
The molecule of the title compound is shown in Fig. 1 and crystal packing projection along the b axis is shown in Fig. 2.

Experimental
The preparation of title compound was adapted from previously published procedure with a slight modification (Promarak & Ruchirawat, 2007). Aqueous sodium carbonate solution (2M, 10.5 ml) was added into a solution of 2,5-dibromo-1,4-bis(hexyloxy)benzene (1.50 g, 3.44 mmol) in dry THF prior to addition of Pd(PPh 3 ) 4 (0.21 g) catalyst. This was followed by the addition of 2-thiophene boronic acid (1.32 g, 10.32 mmol) and the mixture was heated under reflux overnight in dry N 2 atmosphere and allowed to cool to ambient temperature prior to addition of water. The product was extracted into CH 2 Cl 2 and the organic phase was combined, washed with water and brine solution, followed by drying over anhydrous MgSO 4 . The solvent was evaporated using rotary evaporator and the product was further recrystallized from ethanol/ethyl acetate to afford crystals suitable for single-crystal X-ray diffraction (yield: 80%).

Refinement
The H atom positions were calculated geometrically and refined in a riding model approximation with C-H bond lengths in the range 0.93-0.97 Å and U iso (H) = 1.2U eq (C) except methyl group where U iso (H) = 1.5U eq (C).

Computing details
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009) and publCIF (Westrip, 2010  The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. Symmetry code for atoms with the A label: -x, 1 -y, 1 -z. 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 > σ(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.