Synergy between chemo- and bio-catalysts in multi-step transformations.

Cascade synthetic pathways, which allow multi-step conversions to take place in one reaction vessel, are crucial for the development of biomimetic, highly efficient new methods of chemical synthesis. Theoretically, the complexity introduced by combining processes could lead to an improvement of the overall process; however, it is the current general belief that it is more efficient to run processes separately. Inspired by natural cascade procedures we successfully combined a lipase catalyzed amidation with palladium catalyzed coupling reactions, simultaneously carried out on the same molecule. Unexpectedly, the bio- and chemo-catalyzed processes show synergistic behaviour, highlighting the complexity of multi-catalyst systems.

Tunable command layers for liquid crystal alignment.

A simple method for the construction of a stable, tunable, self-assembled command layer for liquid crystal display purposes is described. A pyridine-functionalized oligosiloxane spontaneously forms an anisotropic, grooved surface on indium-tin-oxide, enabling it to align liquid crystalline molecules. The pyridine functions act as seeds for the epitaxial growth of stacks of highly ordered zinc phthalocyanines, the height of which can be controlled. These stacks increase the interaction between the surface and the liquid crystalline matrix by amplifying the surface ordering into the liquid crystal bulk. By varying the height of the stacks, direct control over the properties of the liquid crystal domains is achieved. These properties can be further tuned by adding to the liquid crystal, micro- and nanomolar concentrations of nitrogen-containing compounds, which are capable of interacting with and dissolving the stacks. The procedures we describe offer possibilities to use such tunable systems in LCD-based sensor devices as well as in solar-cell applications.