Crystal structure and optoelectronic properties of 2,7-di(thiophen-2-yl)-9H-4,5-diazafluorene and 2-(2,7-di(thiophen-2-yl)-(4,5-diazafluoren-9-ylidene))malononitrile
D. A. POTAPOV1,2, A. A. SONINA1, C. S. BECKER1, I. K. SHUNDRINA1, M. S. KAZANTSEV1
1Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: 4,5-diazafluorene, Knoevenagel condensation, photoluminescence, charge transport
Abstract
Two thiophene-containing diazafluorene derivatives were synthesised: 2,7-di(thiophen-2-yl)-9H-(4,5-diazafluorene) (TDAF) and 2-(2,7-di(thiophen-2-yl)-(4,5-diazafluoren-9-ylidene))malononitrile (TDAF-CN). Their crystal structures, optical, physicochemical, and semiconductor properties were studied. The target compounds were obtained using the Kischner-Wolff reduction and Knoevenagel condensation. The crystal structure of the compounds was solved by X-ray diffraction. The formation of π-stacking and C-H···π-interactions was revealed. The compounds were demonstrated to undergo partial thermal degradation during sublimation in an inert atmosphere. TDAF-CN was determined to have a deep lowest unoccupied molecular orbital level of -3.99 eV. The photoluminescence quantum yield for TDAF was determined to be 53 % in solution and 73 % in crystals.
|
