Carbazole-functionalized V-shaped bis-coumarin derivatives as organic luminescent materials

AIEE-active V-shaped fused-biscoumarins: synthesis, photophysical and electroluminescence properties

“…1A, there are two molecules in the crystal structure of CC-TriPE , each V-shaped fused-biscoumarin core in both CC-TriPE molecules is not in a plane, and the twist angles between two single coumarin rings are 23.38° and 26.23°, respectively. These twist angles are much larger than that of the previously reported V-shaped fused-biscoumarin derivatives (4.00–8.00°), 36,37 which could be a result of the steric hindrance of the triphenylethene group. Furthermore, in the crystal lattice of CC-TriPE , there are four CC-TriPE molecules, and there are strong π–π stacking interactions through the fused biscoumarin skeletons (3.432 Å) between the two adjacent molecules (Fig.…”

“…35 It was found that the PLQY of the V-shaped fused-biscoumarin core was lower than that of the functionalized V-shaped fused-biscoumarin compounds with triphenylethene, tetraphenylethene and triphenylamine groups, which may be due to the formation of a D-A structure, so that their HOMO and LUMO were separated, resulting in a relatively high PLQY. 49 Compared with the compounds ( CC-Cz and CC-2Cz ) in our previous work, 36 we can see that the EL performances of the doped devices of the compounds CC-2Cz , CC-Cz and CC-TPA were better than those of CC-TriPE and CC-TPE , which was due to the fact that phenylcarbazole, phenyldicarbazole and triphenylamine groups have strong electron-donating ability and excellent hole-transporting characteristics to balance the charge-transfer properties. Although triphenylethene and tetraphenylethene have a certain electron-donating ability, they have relatively weaker electron-donating and hole-transporting abilities compared with phenylcarbazole, phenyldicarbazole and triphenylamine groups, resulting in their EL performances not as good as those of the compounds CC-2Cz , CC-Cz and CC-TPA .…”

“…The compounds CC-TPA , CC-TPE and CC-TriPE were synthesized by the Suzuki cross-coupling reaction between the V-shaped fused-biscoumarin boronic ester and 4-bromotriphenylamine or 1-(4-bromophenyl)-1,2,2-triphenylethylene or 2-bromo-1,1,2-triphenylethylene, respectively, in the presence of K 2 CO 3 and Pd(PPh 3 ) 4 at 60 °C, while the precursor V-shaped fused-biscoumarin boronic ester was prepared according to the previously reported method. 36 The compounds CC-TPA , CC-TPE and CC-TriPE were purified by column chromatography to obtain pure products as yellow solids, and characterized by NMR spectra ( 1 H and 13 C) and high resolution mass spectra. The molecular structures of CC-TPA and CC-TriPE were further confirmed by X-ray crystallography.…”

“…The EL performances of CC-TPA were superior to those of CC-TriPE and CC-TPE , which may be attributed to the balanced charge-transfer properties that resulted from the excellent electron-donating ability and hole-transporting characteristics of the TPA unit. 36,48…”

“…, 3-(diethylamino)-10-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6 H ,7 H -chromeno[3,4- c ]chromene-6,7-dione), were prepared following a previously reported method. 36 The synthetic processes of the targeted compounds are performed as follows:…”