X-Shaped Tetraphiles Liquid Crystalline Multicolor Tilings

5 X-Shaped Tetraphiles Liquid Crystalline Multicolor Tilings 

Attaching two different and incompatible chains, one an Rp-chain and at the opposite side an alkyl chain or any other chain which is incompatible with the Rp-chain (such as the carbosilane chain Rsi in compounds 188—190, Figs. 62-64) offers the possibility of creating liquid crystalline honeycombs with cells of different composition. If projected on a Euclidian plane, such a structure can be described as tiling by two or even more different color tiles (multi-color tilings) [42], 

Recently, polyphilic compounds have been reported, where an Rp-chain and a carbosilane chain were attached at opposite sides of a terphenyl or oligo (p-phenylene ethinylene) core [42], Compound 188 with the longest oligo (p-phenylene ethinylene) core shows two hexagonal columnar phases separated by a thermoreversible continuous (second order) phase transition with critical behavior upon approaching the transition temperature. Based on XRD data it was 

Compound 189 with a shorter terphenyl rod-like core also has two Colhex phases, formed by cylinders, but with a hexagonal cross sectional area (Fig. 63). In this case a complete segregation of the Rp-chains from the RSi-chains is impossible as it would lead to a packing frustration and therefore formation of cylinders incorporating mixed chains cannot be avoided. Based on simulation results [346], XRD data, and AFM results, the two color tiling with a p6mm superlattice 

Rh = 3 1, because the molecules between adjacent squares have to give their Rsi-chains into one of the adjacent RF filled squares [42], Note that in this structure the number of distinct columns is larger than the number of incompatible chains attached to the rod-like core. This means that mixing of the distinct chains gives rise to additional colors which further enhances the complexity of LC self-assembly. 

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