Three types of discotic trimers have been realized: linear, branched (star-shaped), and metal-bridged triple decker (Figure 4.1). In a linear trimer, three discotic units are connected with two ¨exible spacers (Figure 4.1a); in a star-shaped trimer, three discotic fragments are linked to a central core (Figure 4.1b); while the triple deckers consist of three disks connected to each other via two central atoms (Figure 4.1c). Triphenylene, pyranose sugars, alkynylbenzene, phthalocyanine, porphyrin, and hexabenzocoronene (HBC)-based discotic mesogens have been exploited to prepare discotic trimers. The chemistry and physical properties of these trimers are presented in the following sections.