Curved Polar Dibenzocoronene Esters and Imides versus Their Planar Centrosymmetric Homologs: Photophysical and Optoelectronic Analysis

Isomeric columnar liquid crystalline dibenzo[ a, j ]coronene-tetracarboxylic tetraesters and bisimides that differ only by having either a centrosymmetric bis-peri or a polar bis-ortho substitution pattern, exhibit striking differences in the makeup of their electronic ground and excited states as well as in their performance as emitters in electroluminescent diodes. Quantum chemical calculations show that the key molecular orbitals consist essentially of perylene-like ones responsible for the longest-wavelength absorptions and coronene-like ones responsible for the very intense shorter-wavelength absorptions with modifications, in particular for the ortho -imide due to its pronounced deviation from planarity. Additionally, the ortho -imide and ortho -ester, which tend to a slipped-stacked configuration within their columns due to their nonplanarity, strongly outperform their peri-counterparts as emitters in organic light emitting diodes.