A method for the preparation of uniaxially oriented thin films of terthiophene (20–50 μm thick) is introduced. It relies on the crystal growth with a Bridgman-type process that decouples nucleation and growth phenomena. An effective thermal gradient of 6–11.6 °C/mm has been used in which the sample (terthiophene powder deposited on either glass or fluorinated glass substrates) is displaced from a hot zone to a cold zone at a constant rate of 2.5–5 μm/s. The size and orientation of crystals have been investigated by polarized optical microscopy and X-ray diffraction measurements. A coexistence of two polymorphs of terthiophene has been observed, but optimal gradient conditions enabling the selective crystallization of only the room temperature stable polymorph have been found. Terthiophene films deposited on fluorinated glass substrates and crystallized using the thermal gradient technique show a stronger tendency to polymorphism and random orientation of crystallites for all gradient conditions tested. The monoclinic unit cell (a = 15.410 Å, b = 5.709 Å, c = 26.052 Å, β = 97.77°) of the room temperature phase orients its ab plane parallel to the substrate. Pole figures demonstrate the growth of uniaxially aligned crystals with the [100] and [−100] directions along the gradient axis. Finally, a tentative explanation for this peculiar in-plane orientation is given based on crystal morphology calculations.

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This paper describes the synthesis and physicochemical characterization of novel metal-free phthalocyanines Pc(SO 2 R) 8 , bearing eight peripheral alkylsulfonyl substituents. The key synthetic step is the efficient eightfold oxidation of sulfanyl (SR) into sulfonyl (SO2R) functions in the precursor Pc(SR) 8 . Quantum-chemical calculations show a considerable stabilization of the HOMO and LUMO levels of Pc(SO 2 R) 8 as a result of the presence of the strongly electron-withdrawing groups, while the HOMO−LUMO gap remains nearly unaffected. The redox behavior and electronic spectra of Pc(SO 2 R) 8 were investigated by cyclic voltammetry and electronic absorption spectroscopy, respectively, to confirm the theoretical predictions. Particularly noteworthy is the first reduction potential of −0.14 V vs the saturated calomel electrode (SCE), which falls within the empirically established air-stability window for n-type semiconductors. Supramolecular structures of mesophases of Pc(SO 2 R) 8 and their synthetic precursors Pc(SR) 8 were studied in detail with the aid of powder X-ray diffraction in combination with differential scanning calorimetry and polarized light optical microscopy. As it was demonstrated earlier for many different discotic mesogens, installation of either linear or swallow-tail branched peripheral alkyl substituents plays an important role in the formation of mesophases. However, an unusual behavior was found for the Pc(SO 2 R) 8 series: swallow-tail alkyl chains resulted in higher order in columnar mesophases compared to the linear analogues.