Liquid crystals are seldom used to create optimized high-performance electronic materials. Planar organometallic complexes that can assemble into columnar or disk like phases generating extended intermetallic interactions are seen as candidates for such applications.
Markrete Krikorian, Shuang Liu, and Timothy M. Swager, Massachusetts Institute of Technology (MIT), Cambridge, USA, designed cationic square planar Pt(II) complexes with high degrees of Pt···Pt intermolecular association. The strong intermolecular associations promote liquid crystalline and mechanochromic behavior.
Although they have only a single side chain and no multiple alkyl side chains, complexes of the 3a series (pictured) show thermotropic columnar liquid crystalline behavior. They formed discotic liquid crystals with columnar hexagonal packing.
In the crystal form, two distinct polymorphs of 3a SbF6 were identified. These can be interconverted by mechanical force, melting, or solvent exposure.
According to the authors other cationic organometallic structures will display similarly strong intermolecular interactions. Therefore, this approach has potential in creating materials that are mechanically, thermally, and chemically responsive.
- Columnar Liquid Crystallinity and Mechanochromism in Cationic Platinum(II) Complexes,
Markrete Krikorian, Shuang Liu, Timothy M. Swager,
J. Am. Chem. Soc. 2014.