Synthesis, optical characterization and thin film preparation of 1-(pyridin-2-yl)-3-(quinolin-2-yl)imidazo[1,5-a]quinoline

An efficient synthesis for 1-(pyridin-2-yl)-3-(quinolin-2-yl)limidazo[1,5-a]quinoline (PCIC) is presented. Molecular properties as well as thin film deposition and characterization are reported. With an ionization energy of 5.5 eV estimated from cyclic voltammetry and a quantum yield of 28% as determined in solution, the molecule proved promising as possible component of light emitting devices. Therefore, studies in the solid state of PCIC were conducted. Thin films of PCIC were obtained by physical vapor deposition whose morphology was analyzed by atomic force microscopy. Crystals of the molecule were grown by recrystallization from solution or by en trainer sublimation. The structure of crystals depending on preparation route was analyzed by XRD and the results were used to discuss the structure in thin films. Photoluminescence characteristics were investigated in detail for the crystal needles and the vapor-deposited thin films, showing a dependence of emission maximum and the fine structure of bands on the molecular packing. The desired blue emission was measured even at air which is promising for technical application of the material and proves its stability against oxidation.