Hydrogen bond-driven columnar self-assembly of electroluminescent D–A–D configured cyanopyridones

Abstract

Herein, we report the design and synthesis of a new series of flying bird-shaped liquid crystalline (LC) cyanopyridone derivatives with a D–A–D architecture, CPO-1 to CPO-4. Their mesomorphic, photophysical, electrochemical, and electroluminescence characteristics have been investigated in detail. Here, the H-bonding interactions through a central lactam core were shown to be the key driving force for their self-assembly into columnar mesophases. The key role of H-bonding has been confirmed by using newly synthesized similar shaped compounds, MCP-1 to MCP-3. New CPO mesogens were found to be intense greenish blue light emitters with narrow band-gap energies. Conclusions were drawn based on theoretical studies also. Finally, the application potential of the selected mesogen CPO-2 as an emissive material has been demonstrated for the fabrication of doped and non-doped OLED devices with different device architectures, which displayed encouraging results. In fact, this is the first report on the use of emissive H-bond-assisted columnar liquid crystals in devices. The present results provide a new guideline and a versatile approach to the design of new LC molecules for the fabrication of efficient OLEDs.