Adamantane Substitution Effects on Crystallization and Electrooptical Properties of Epindolidione and Quinacridone Dyes

The synthesis, experimental and theoretical study of the novel air-stable four adamantane-bearing dyes based on the trans-epindolidione (EPI) and trans-quinacridone (QA) cores are presented. Compared to the parent EPI and QA, the methyl-/ethyladamantyl substitution ensures that their structural stability in crystals is preserved due to the self-organizing properties of adamantyl groups. The investigated materials are solution-processable in common organic solvents and possess excellent thermal stability. The very good solubility was achieved by a one-step short and easy synthesis, which resulted in moderate yields of a new family of synthesized dyes. The ethyladamantyl EPI derivative (3) exhibits a unique rise in thermal stability reaching 412 degrees C. The resulting electrochemical band gap carried out on thin-film evaporated on ITO-coated glass electrodes was in the range of 2.4-2.5 eV. The experimental HOMO energies range from -6.2 to -6.0 eV, and LUMO energies lay between -3.7 and -3.5 eV. The prepared compounds are characterized by strong fluorescence in solutions and in powder, suggesting a decrease in the extent of non-radiative relaxation processes.