Star‐Shaped Mesogens

Abstract

Star‐shaped molecules are exciting non‐conventional mesogens in which more than two linear arms are symmertrically attached to a core building block via covalent or supramolecular bonds. The molecular structures comprise flexible, semi‐flexible and shape‐persistent scaffolds which may realize all kinds of mesophase topologies by nanosegregation. This requires different modes of self‐assembly depending on the mesogen structure, flexibility and void between the arms. Functionality can be incorporated by cores, arms and guest molecules generating multifunctional, highly organized complex materials for applications.

Free Space in Liquid Crystals—Molecular Design, Generation, and Usage

“…In most of these studies, space-filling was not in the focus of research as a concept to tailor LC phases. Our interest in shape-persistent star-shaped molecules 19 (Figure ), which are related to the morphology of the CPI mesogens 17 and 18 , arose from the fact that in the series of previously studied star-shaped semiflexible oligobenzoates their folding was not easily predictable, which prevented the success of our long-term research goal to create nanostructures in columnar phases with different functional building blocks and high spatial control. , The Mercedes-like stars 19 , previously studied by Meier et al, possess intrinsic free space but on the other hand always assemble in Col h phases, irrespective of the magnitude of the intrinsic void . This is in stark contrast to molecules 14a , 17 , and 18 , which form either nematic or crystalline phases as a consequence of void compensation.…”

“…They are surrounded by host molecules in a columnar stack of these supermesogens, and therefore, such structures may be considered as new liquid-crystalline ENDO receptors. Comparable semiflexible melamine star mesogens, which were comprehensively studied with respect to their host–guest chemistry, were able to take up only a single guest by hydrogen bonding. , …”