Liquid crystalline PAH oligomers
The Thies group has recently discovered that supercritical extraction (SCE) can be used to isolate monodisperse polycyclic aromatic hydrocarbon (PAH) oligomers with liquid crystalline properties from carbonaceous oligomers of broad molecular weight distribution. Although the species within a given oligomer number have essentially the same molecular weight, the isomeric nature of these materials creates a significant melting-point depression, invoking the desired liquid-crystalline behavior. Supercritical extraction is playing a key role in this work, not only in the isolation of the liquid crystalline PAH oligomers but also in the determination of their molecular structures. Finally, the relationship between the tendency of various PAH oligomers to exhibit liquid crystallinity and their molecular properties is also of interest.