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Tuning photophysical properties of iridium(III) 2-arylbenzimidazole complexesтезисы доклада
- Авторы: Bezzubov S.I., Doljenko V.D., Kiselev Yu M.
- Сборник: Thesises of XXth EuCheMS Conference on Organometallic Chemistry
- Тезисы
- Год издания: 2013
- Место издания: University of St.Andrews.// St. Andrews, Scotland, UK
- Первая страница: 63
- Последняя страница: 63
- Аннотация: Cyclometalated iridium complexes are of great interest for OLEDs, chemosensors, and solar cells applications because of their promising photophysical properties. Still, the required extinction coefficients of the complexes in visible range were not reached. In contrast to other N^C aromatic donors used in iridium(III) chemistry, 1-phenyl-2-arylbenzimidazole ligands can be easily modified by conventional chemical reactions, that affected immediately the electronic environment of iridium through highly conjugated heteroaromatic system. Here we present a series of 1-phenyl-2-arylbenzimidazoles in which the aryl units are phenyl ring substituted with electron-withdrawing (F, Cl) or electron-donating (OMe, NMe2) groups at their para- (and meta-) positions (see Figure). The ligands were used for preparation of bis-cyclometalated iridium(III) cationic complexes with 4,4'-dicarboxy-2,2'-bipyridine and 11-carboxydipyrido[3,2-a:2',3'-c]phenazine as ancillary ligands. The complexes were fully characterized by NMR, elemental analysis, TGA/DSC, and mass spectra. Single crystals of complexes 1a, 1b, 5a, 5b were analyzed by X-ray diffraction. While chloro- and fluoro-substituents caused a little hypsochromic shift of the absorption maxima if compared to the complex of unsubstituted 1,2-diphenylbenzimidazole (1), introduction of methoxy- and dimethylamino-substituents gave rise to a bathochromic shift of about 100 nm. The complexes had a strong emission in yellow-to-red region in solution at room temperature. Changing the substituents in the ligangs caused blue- and red-shifts in the same way as in absorption spectra. Cyclic voltammetry (CV) studies of the complexes indicated reversible oxidation potentials in most cases. The DFT-optimized geometries of the complexes 1a, 1b, 5a, 5b were in good agreement with the crystal structures. The experimental data were well-correlated with calculated HOMO-LUMO gaps of the complexes (B3LYP/6-31G LANL2DZ) and the electrochemical oxidation potentials measured.
- Добавил в систему: Киселев Юрий Михайлович