Triarylamines with branched multi-pyridine groups: modulation of emission properties by structural variation, solvents, and tris(pentafluorophenyl)borane

Six triarylamine derivatives 1 – 6 with branched multi-pyridine substituents were prepared and characterized. These compounds are distinguished by the substituent on one of the phenyl group with NO2 for 1 , CN for 2 , Cl for 3 , p -C6H4OMe for 4 , OMe for 5 , and NMe2 for 6 , respectively. As revealed by single crystal X-ray analysis, these substituents play an important role in determining the configuration of the triarylamine framework and the crystal packing of 1 – 6 . The emission properties of these compounds were examined in different solvents (toluene, CH2Cl2, acetone, tetrahydrofuran (THF), and N , N -dimethylformamide (DMF)) and in solid states. Distinct dual emissions from the localized emissive state and the intramolecular charge transfer state were observed for compound 5 in CH2Cl2. Compounds 1 and 6 show apparent aggregated enhanced emissions in acetone/H2O. The emission properties of these compounds were further modulated by the addition of tris(pentafluorophenyl)borane. In addition, density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed on the ground and singlet excited states to complement the experimental findings.