Room-Temperature Fluorescent n-Type Columnar Liquid Crystals Based on Perylene Hydrazides

Symmetrical and unsymmetrical perylene hydrazide derivatives were designed and synthesized, and their properties were investigated. The unsymmetrical perylene derivative features a hydrazide unit at one end of the perylene molecule and a swallow-tail amine (HI) or a diester moiety (HE) at the other end, exhibiting a room-temperature columnar mesophase. All three molecules were found to be thermally stable at high temperature, and the unsymmetrical perylene derivatives HI and HE have shown columnar phases of hexagonal symmetry. Photophysical studies reveal the highly fluorescent nature of HI and HE, with the latter showing a higher relative quantum yield and bright red emission in the solid state as well. All three derivatives were investigated for their charge carrier mobility measurements by the space-charge-limiting-current (SCLC) method in an electron-only device. Among the three molecules, it was seen that the symmetric derivative HH showed higher electron mobility, though it did not stabilize any liquid crystalline phase.