Liquid crystals are a successful example of how the control of self-assembly via chemical design leads to novel applications. Direct patterning of a continuous metal-free mesogenic phthalocyanine film (discotick liquid crystals) is shown by the spatial control of columns orientation by unconventional lithography. These patterned films work as time-temperature integrators at a columnar rectangular-hexagonal transition temperature

Interfacial stress changes at electroactive self-assembled monolayers have been investigated by monitoring the potential-induced deflection of Au-coated microcantilevers modified with 12-ferrocenyl-1-dodecanethiol in aqueous perchloric acid solution. Oxidation of the surface-bound ferrocene generates a compressive surface stress which results in the cantilever bending away from the film-coated Au surface. The origin of the redox-induced stress change that occurs at these close-packed monomolecular films is discussed.

Blends of two metal-free phthalocyanine mesogens exhibiting different mesophases (Col r phase from room temperature to isotropization for the first one, and Col r at room temperature then Col h from around 60 °C to isotropization for the second one) have been studied in order to determine the relationship between the type of mesophase and the alignment behavior. The phase diagram of this system has been built and evidence of full solid-state miscibility of the two pure constituents in all proportions and temperatures is presented. Investigation of phase alternation at room temperature as a function of composition revealed that border compositions exhibit Col r phases similar to the pure constituents, whereas Col h mesophase was stabilized for intermediate compositions. Combined polarized optical microscopy observations and X-ray diffraction measurements showed that homeotropic alignment is adopted only for mixed samples exhibiting Col h mesophase, thus demonstrating that the presence of a Col h mesophase is a necessary condition for homeotropic alignment.

A new phase of a known discotic liquid crystal is observed at the interface with a rigid substrate. The structure of the substrate-induced phase has been characterized by atomic force microscopy, specular X-ray diffraction, and small-angle and wide-angle grazing incidence X-ray diffraction. The substrate-induced phase, which has a thickness of ∼30 nm and a tetragonal symmetry, differs notably from the bulk phase. The occurrence of such phase casts a new light on alignment of discotic liquid crystals.

Synthesis, isolation, and characterization of derivatives of an anthrathiophene dimer (TOTBAT) and of anthradithiophene oligomers (ADTO), possessing octylthiophene units on their backbone, are described. These semiconductors are prepared through oxidative copper(II) chloride coupling. The spectroscopic properties and stability of these newly synthesized semiconductors were evaluated and supported by quantum-chemical calculations.

a b s t r a c tNovel, push-pull chromophores combining a cationic benzothiazolium acceptor moiety and either one or two thiophene rings as a part of the conjugated p-system between the donor and the acceptor moieties have been synthesized and characterized. The chromophores displayed pronounced quadratic NLO activity with their first molecular hyper polarizabilities in agreement with their linear spectral properties.

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