Exploring the Ambipolar Charge Carrier Mobility, Mesomorphic, and Gel Properties in Nitrile Extended Quinoxaline and Phenanthro[a]phenazine Discotic Liquid Crystals

A set of cyano-substituted dibenzo-quinoxaline and phenanthro-phenazine discotic mesomorphs have been synthesized, and the impact of ring closure on thermal, optical, electronic, and physical properties has been investigated. Although dibenzo-quinoxaline shows incredible fluorescence and a low-temperature mesophase, a straightforward ring closure has decreased the molecular distortion in the case of phenanthro-phenazine, thereby resulting in a more stable arrangement. A robust columnar hexagonal self-assembly in the phenanthro[ a ]phenazine compound facilitates a hole mobility of 1.02 × 10 –2 cm 2 V –1 s –1, which is 100-fold more than that of the dibenzo quinoxaline analogue. This demonstrates the tunability in self-assembly as well as the physical and electronic properties of discotic liquid crystalline materials with a simple modification in the chemical structure. A study of their gelation properties has also been explored, and models of the organization of molecules within the individual fiber in the gel network have been proposed in agreement with X-ray diffraction studies. These two sets of low band gap ambipolar materials have significant potential to be used in the fabrication of various optoelectronic devices.