The synthesis, characterization, and mesomorphic properties of a new type of liquid-crystalline twin bearing a pentadecyloxytriphenylene subunit tethered via a decyl spacer to a chiral pentakis(3,7-dimethyloctyloxy)-triphenylene are reported. The target compound displays a hexagonal columnar mesophase, which is metastable at room temperature.Introduction. ± Among the two major classes of thermotropic liquid crystals, i.e., calamitic (rod-shaped) and discotic (disk-shaped) liquid crystals, the latter type, which forms columnar short-range-ordered assemblies in the mesophase, has attracted many researchers during the last decade [1] [2]. The interest in discotic liquid crystals is mainly due to their promising physical properties, such as electrical and photoconductivity, and high charge-carrier mobility along the columns [3]. From this work, the so-called columnar twins or oligomers have emerged recently, constituting two or more discotic subunits connected to each other by a flexible spacer [4]. 2,3,6,7,10,11-Hexasubstituted triphenylenes are ideally suited building blocks for columar liquid crystals, and many examples of both symmetrical and unsymmetrical twins based on triphenylenes are known (for recent examples, see [5]). However, only few polymeric liquid crystals and columnar twins containing chiral triphenylenes have been published so far (for chiral polymeric triphenylenes, see [6]; for chiral monomeric triphenylenes, see [7]). Particularly attractive to us seemed unsymmetrical twins bearing chiral and achiral moieties of similar sizes, because these twins might be able to form different chiral and achiral microdomains within a columnar mesophase. The presence of chiral subunits might induce helical twisting of the columns, which is a prerequisite for ferroelectricity [8]. Those unsymmetrical dimers may either retain the mesomorphic properties of the subunits by columnar stacking of like subunits, or form supramolecular aggregates by columnar stacking of unlike subunits and thus display novel mesomorphic properties. As shown in Fig. 1, four different orientations are conceivable, i.e., a) formation of two-dimensional domains within one lattice sheet, b) an intracolumnar regular ordered pattern, with the chiral and achiral subunits being segregated in different columns, c) an intracolumnar regular mixed pattern, with chiral and achiral subunits of neighboring twins stacked alternatively within the columns, and d) an intracolumnar randomly mixed pattern [9]. The micro-segregation in a ± c should lead to different mesomorphic properties, e.g., increased phase stability, as compared to