Symmetry versus asymmetry: Synthesis and studies of benzotriindole-derived carbazoles displaying different electrochemical and optical properties. (February 2016)

• Record Type: Journal Article
• Authors: Reghu, Renji R.; Volyniuk, Dmytro; Kostiv, Nataliya; Norvaisa, Karolis; Grazulevicius, Juozas V.
• Is Part Of: Dyes and pigments. Volume 125(2016)
• Page Start: 159
• Page End: 168
• Publication Date: 2016-02
• Subjects: Benzotriindole -- Carbazole -- Hole-transport -- Cyclic voltammetry -- Ionization potential -- Glass-transition; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2015.10.013
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Symmetrically and asymmetrically derived benzotriindole (diindolocarbazole) cores and their triply functionalized carbazolyl derivatives were synthesized and characterized. The synthesized compounds showed relatively high glass-transition temperatures. Carbazolyl substitutions at the periphery of benzotriindole cores improved their glass-forming ability as well as the thermal stability. Asymmetric benzotriindoles showed red-shifted absorption and emission spectra. Relatively decreased optical band gaps of the asymmetric derivatives suggested pronounced electronic communication between the indole segments and more effective π-conjugation in these derivatives. Oxidative redox profiles were distinct for differently linked benzotriindoles as characterized by cyclic voltammetry. Asymmetric benzotriindoles oxidized at comparatively lower potential and facilitated electropolymerization. Ionization potentials of thin films of the benzotriindole derivatives measured by photoelectron spectroscopy ranged from 4.95 to 5.43 eV. The method of charge extraction by linearly increasing voltage unlocked the hole-transport in both the symmetric and asymmetric benzotriindoles. Symmetric nature of benzotriindoles promoted the hole-transport in thin films. Graphical abstract: Highlights: Symmetric and asymmetric benzotriindole derivatives were synthesized. Difference in symmetry significantly influenced the properties of benzotriindoles. The benzotriindoles showed relatively high glass-transition temperatures. Decrease of symmetry in benzotriindoles resulted in red-shifted absorption spectra. Asymmetry in carbazolyl substituted benzotriindole enabled electropolymerization.