Studies on ultrathin films of tricycloquinazoline (TCQ) based discotic liquid crystal molecules

The assembly of disk-shaped molecules on surfaces has drawn considerable attention because of their unique electro-optical properties. We have studied the monolayer of the tricycloquinazoline based disk-shaped (TCQCB) molecules at air-water and air-solid interfaces. The TCQCB molecules form a stable Langmuir monolayer at the air-water interface. The monolayer exhibits gas, low density liquid (L1), and high density liquid (L2) phases. In L1 and L2 phases, the molecules prefer edge-on conformation. The atomic force microscope study on the Langmuir-Blodgett films of the molecules reveals a structural transformation. The elongated domains in the film deposited in L1 phase transformed to a compact grainy texture in the film deposited in the L2 phase.