A series of α,ω‐cyano oligothiophenes with three to six rings, as well as seven β,β′‐substituted cyano terthiophenes have been synthesized using a palladium‐catalyzed coupling reaction via organotin or organozinc intermediates. The structure of an oliothiophene trimer has been determined by X‐ray crystallography; its space group is monoclinic (C2/c) with four molecules per unit cell (Z = 4). The molecules adopt the π–π stacking structure. UV‐vis spectra of these materials as thin films show a bathochromic shift compared to unsubstituted oligothiophenes. These bathochromic shifts are interpreted in the light of charge transfer exciton. Cyano end‐capped sexithiophene (CN‐6T‐CN) sandwiched between various metals (metal/CN‐6T‐CN/metal), to form Schottky diode structures, were fabricated by vapor deposition. The electron injection and rectification ratio strongly depend on the metal contact, namely the work function of the metal is compatible with the electron affinity of the organic material. The current–voltage results are compatible with n‐type conduction in CN‐6T‐CN.

International audienceHerein we describe the synthesis of new substituted tetraaryltetracenes, obtained by the dimerization of triarylchloroallenes, prepared from propargyl alcohols. The propargyl alcohols were prepared by two different synthetic strategies and then the alcohols were treated to obtain the corresponding acenes. In addition to the expected tetracene derivatives, we observed the formation of bis(alkylidene)cyclobutenes. When strong electron-donating substituents were present, the main product was the cyclobutene. We discuss a reaction mechanism that accounts for the formation of the cyclobutenes

The polarized UV-visible absorption spectra of dibenzo[d,d']thieno[3,2-b;4,5-b']dithiophene single crystals are reported and interpreted to definitively attribute the observed bands and their polarizations. The results provide information on the intermolecular interactions and on the aggregation in the condensed phase, which can be of either herringbone- or H-type, depending on the electronic transition taken into considerations, with consequences on the order and polarization of the absorption bands. A relatively easy method is also discussed to obtain information on the structural/morphological properties of different types of samples, including thin films, which have been recently proposed for high-performance organic film-effect transistors for their high ionization potential and photostability.

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