Mesomorphism of Protodendritic Oligomers

Abstract

New liquid-crystalline protodendritic oligomers with dimesogenic side arms are reported. These “starlike” tetrapedes were obtained by modular synthesis involving the sequential association of different anisotropic promesogenic units within the molecular architecture. This synthetic methodology allowed to prepare tetrapedal oligomers with homolithic (all identical blocks) and conjugated heterolithic (different blocks) structures. The mesomorphism was largely influenced by the peripheral aliphatic chain substitution and to a lesser extent by the chemical nature of the primary constitutive building bricks (tolane and/or stilbene fragments). Indeed, depending on the number of terminal chains grafted onto the terminal mesogens, either columnar phases, resulting from the one-dimensional stacking of supramolecular disks of ∼3−6 supermolecules in fan conformation, or smectic phases, induced by the lateral two-dimensional registry of the supermolecules in cylindrical conformation, were induced. Some of the branche...