Two solid catalysts in which a chiral copper(II) bisoxazoline has been covalently anchored on silica and MCM-41 have been prepared; the solids are enantioselective catalysts (up to 92% ee) for the Friedel-Crafts hydroxyalkylation of 1,3-dimethoxybenzene with 3,3,3-trifluoropyruvate.

Using several experimental techniques, we have investigated the thermodynamics and the structure of the bulk, monolayers, and multilayers of new three-block organosiloxanes based on the pentyloxy-4′-cyanobiphenyl mesogenic unit. Compared to conventional amphiphiles or smectogens, these molecules contain an additional siloxane moiety whose bulkiness was gradually increased. This enables fine tuning of the steric effect imposed by the siloxane parts and allows determination of the balance between moleculesubstrate and molecule-molecule interactions as well as of the effect of the siloxane end group on the microscopic structure, order, and film homogeneity. We show that the three-and two-dimensional behaviors are highly correlated and are determined by the subtle balance between these interactions. We particularly showed that surface effects induce a three-layer smectic film whatever the bulk state. Various 2D phenomena have been observed such as wetting, mono-and bilayer melting, liquid droplet freezing, several 2D phase transitions, and a tricritical point. These are reversible phenomena and easily controllable via lateral density change, making the present organosiloxane molecules a good model system to investigate in much more detail some challenging physical aspects in two dimensions.

The design, the synthesis and the mesomorphic properties of a new disc-like mesogen based on a hexasubstituted triphenylene core terminated with pentamethyldisiloxane pendant groups are reported. The siloxane fragments were grafted to the six terminal olefinic branches of a triphenylene precursor by a Pt-catalysed hydrosilylation reaction. Both the hexaolefinic and the hexasiloxane derivatives are mesomorphic, showing a rectangular columnar (Col R -p2gg) mesophase between 55 and 88 uC for the former, and a broad hexagonal (Col H -p6mm) mesophase between ambient temperature and 125 uC for the latter. The liquid crystalline behaviour was investigated by means of differential scanning calorimetry, polarised-light optical microscopy, and X-ray diffractometry. The mesophase temperature range and stability were considerably extended for the hybrid compound with respect to the siloxane-free compound. This behaviour is explained on the basis of enhanced microsegregation between the chemically distinct constituent components of the molecule.

We have studied bulk and thin film behavior of a low-molar-mass organosiloxane ferroelectric liquid crystal with a sulfinate as a chiral group. The addition of the siloxane moiety lowers the transition temperature of the bulk smectic phase, increases its thermal stability, and favors a lateral anchoring of the chiral molecules at the air−water interface. The formation of stable monomolecular Langmuir films of this LMM ferroelectric liquid crystal permits the control of the molecular orientation via lateral density changes, and consequently in-situ investigations of the interfacial ordering and orientation. Uniform mono- and multilayer films with well-defined orientation can be transferred onto solid substrate for further studies.

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