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Osmium tris-diphenylphenanthroline perchlorate (Os(DPP) 3 ) can be spread at the air/water interface where it forms solid monolayer films. Brewster angle microscopy revealed that these films consist of irregular ca. 100 to 1000 µm diameter 2D aggregates which coalesce upon compression to form continuous films. Grazing incidence X-ray diffraction data showed that the structure of the aggregates is independent of the degree of monolayer compression and features a 2D lattice of hexagonally close-packed Os(DPP) 3 centers with Os-Os distances of 12.57 Å. The latter is 4 to 24% shorter than the Ru-Ru distances found in the 3D monoclinic crystal of an isostructural Ru (DPP) 3 . Two dimensional electrochemical measurements carried out with line microelectrodes at the air/water interface were used to study kinetics of the lateral electron transport in these Langmuir monolayers. Electron transport involves electron hopping on the 2D lattice of the osmium sites where the individual electron transfer steps between Os II (DPP) 3 and Os III (DPP) 3 take place with the rate constant k 1 ) 4.7 × 10 8 s -1 . Percolation theory was used to account for the observed increase of the electron hopping rates during monolayer compression on the water surface resulting in an increase of the extent of connectivity and thus electroactivity of the initially formed 2D Os(DPP) 3 aggregates. Percolation theory also accounts well for the dependence of the electron hopping rates on the composition of fully compressed Os-(DPP) 3 /Ru(DPP) 3 monolayers in which the ruthenium species were used to homogeneously dilute the Os-(DPP) 3 sites. In contrast, in Os(DPP) 3 /octadecanol monolayers, macroscopic self-segregation of the two components was inferred from a larger positive shift of the apparent percolation threshold in the lateral electron hopping.

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Electro-optical switching of the liquid crystalline Blue Phase exhibits extremely fast response times. However, the unstabilized Blue Phase is characterized by a rather narrow temperature range on the order of a few K. For display applications the operating temperature range needs to be increased. One very promising way is to broaden the stable temperature range by polymer-stabilization of the Blue Phase. Successful stabilization is achieved by proper material selection/matching of reactive mesogens (RMs) and the chiral host. One prerequisite for application in display manufacturing is excellent UV and heat stability as well as good processability. Improvements in relevant performance parameters will be presented and discussed. Fig. 1 Principal constituents of a Blue Phase (BP) mixture include the nematic host mixture, chiral dopant and monomers. 4.4 / M. Wittek SID 2012 DIGEST • 25 ISSN 0097-966X/12/4301-0025-$1.00