Segregated liquid crystalline dendritic supermolecules — multipedes based on pentaerythritol scaffolds

Abstract

A group of chiral nematic multipedal materials based on pentaerythritol containing two types of mesogenic sub-units were synthesised. The presence of different types of mesogens, the topology of the attachment to the core (end-on and side-on) and the chemical nature of the linking connection to the PE scaffold (ether, ester and tetramethyldisiloxane moieties) were used to tailor the mesomorphic properties. The related uniform tetramers have also been studied. The materials were characterised by a variety of techniques including ¹H, ¹³C, ²⁹Si NMR spectroscopy, SEC, MALDI-TOF MS, DSC and POM. The crystalline state was found to be suppressed for most of the materials once they had experienced a first isotropisation process; all exhibited glass transitions near room temperature and accompanying wide temperature range mesophases. The parent supramolecular system carrying just terminally appended mesogens exhibited the smectic A phase, whereas the alternative parent material carrying only laterally attached chiral mesogens exhibited the chiral nematic phase.