Luminescent benzo- and naphthoquinolines: Synthesis and investigation of photophysical properties

The aim of this study was to synthesise new luminescent small molecular weight benzo- and naphthoquinoline derivatives (based on already known synthons) with different substituents (chlorine, tetrazole, iminophosphorane and amine), to characterize them by ultraviolet photoelectron spectroscopy in air (UPS), luminescence and absorption photospectrometry and to investigate the changes in these properties resulted by differences of molecular structure. Measured values of the HOMO, the LUMO energy levels and optical band gap (Eg_opt) were in range EHOMO=[−5,9;−5,5]eV, ELUMO=[−3,6;−3]eV, Eg_opt=[2;2,8]eV. Most of the examined materials showed high intensity fluorescence reaching quantum yields of 49%. Fluorescence peaks of thermally evaporated layers distributed in range of λLayer=[477; 596] nm - from blue to orange colour while in chloroform solution remained in blue-green interval λSolution=[471;537] nm. Primary study results of electroluminescence indicate that the materials have a potential to be used in organic optoelectronics.