Linkage-structure dependences of the spectroscopic and photophysical properties of anthracene derivatives: Tri(9-anthryl)benzene and tri(9-anthryl)borane

The spectroscopic and photophysical properties of 1,3-di(9-anthryl)benzene (DAB), 1,3,5-tri(9-anthryl)benzene (TAB), and tri(9-anthryl)borane (TABO) in tetrahydrofuran were reported, together with those of 9-phenylanthracene (MAB). Although MAB, DAB, and TAB showed structured absorption spectra similar to the 1La band of anthracene in the wavelength region of 300–400 nm, the molar absorption coefficient at the maximum wavelength of TAB was as large as ∼4.2 as compared with that of MAB. Detailed analysis of the absorption data indicated that the absorption transition moment of MAB, DAB, or TAB was 3.3, 4.3, or 6.4 D, respectively. The large absorption transition moment of TAB was discussed on the basis of the electron density distributions in the highest-energy occupied and lowest-energy unoccupied molecular orbitals. In contrast to TAB, TABO exhibited characteristic broad and structureless absorption and fluorescence spectra. The large differences in the spectroscopic and photophysical properties between TAB and TABO were discussed in terms of the effects of the chemical structure of the terminal unit connecting three anthryl groups.