Shape columnar structure

The most comprehensive studies on shape-persistent Hekates have been performed on stilbenoid star-shaped molecules. Structures and mesomorphic properties are collected in Table 1. Core building blocks with only one repeating unit per arm and one flexible chain 26a,b, 28a-d, 30a did not show any liquid crystal properties [56-58]. In the series of two chain derivatives 28e, 30b,c the formation of meso-phases depend on the core [57-59]. The electron deficient triazine and the dicyanopyridine building block induced obviously columnar mesophases. The pyridine derivative 30b showed only a crystalline phase [58]. In the series of nine chain stars 26c-g [60-62] and 28f-n [57], the compounds formed columnar phases depending on the chain length of the peripheral chains. Propyloxy chains are too short but hexyloxy and dodecyloxy chains are sufficient for the formation of liquid crystal phases by nanosegregation [60-62]. This can be rationalised by a dense... 

The columnar phases of oligobenzoate Hekates are most probably formed from -shaped conformers which pack disordered in hexagonal columnar phases and for symmetric mesogens they can tilt and aggregate in highly ordered helical arrangements to form the 3D columnar structures (see Fig. 10a, b). Indications... 

Discotic LC, based on the molecules having disc-like shapes [22, 23, 74], have attracted much attention in recent years owing to their inherent ability to form self-organized columnar structures, which can provide superior charge transport ability... 

Solid state NMR, however, is probably even more powerful for probing the time scale and geometry of rotational motions [14]. For instance, disk-shaped aromatics often stack into columnar structures as part of discotic liquid crystals (DEC)... 

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