Swivel-Cruciform Stilbenes Based on Bithiophene

Author： García-Rodríguez Amaranda Rodríguez Antonio M. Prieto Pilar Andreu Raquel Merino Sonia Rodríguez-López Julián

E-ISSN： 1099-0690|2015|11|2394-2404

ISSN： 1434-193X

Source： European Journal of Organic Chemistry, Vol.2015, Iss.11, 2015-04, pp. : 2394-2404

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Abstract

Bithiophene-based cruciforms with different stilbenoid arms at the 3,3′- and 5,5′-positions have been synthesized by various combinations of Suzuki and Horner–Wadsworth–Emmons (HWE) reactions. According to DFT calculations, the steric hindrance between the arms at the 3,3′-positions produces a twist angle of 57.6° between the two thiophene rings that form the 2,2′-bithiophene unit, an arrangement that leads to a swivel-cruciform structure. The UV/Vis spectra contained strong absorption bands at wavelengths consistent with a twisted molecule with little interaction between the arms. The ability of these compounds to form highly stable radical cations was demonstrated by cyclic voltammetry and this, together with their good solubility in organic solvents, indicates that these materials have potential for the development of solution-processed electronic devices. Bithiophene-based cruciforms with stilbenoid arms at the 3,3′- and 5,5′-positions adopt a twisted geometry owing to steric hindrance between the stilbene arms. This results in weaker intermolecular interactions and better solubility in common solvents. Electrochemical results demonstrate that these systems can support radical cations and show their potential as hole-transporting materials.