Study on photophysical properties of intramolecular charge transfer (ICT) compound: 4-(diphenylamino)biphenyl-4′-boronic acid

A new compound 4-(diphenylamino) biphenyl-4′-boronic acid (DBBA) was synthesized. The optical properties including fluorescence quantum yields and change in the dipole moment in various solvents at room temperature were characterized by the absorption and steady-state fluorescence technique. The emission wavelength of DBBA was very sensitive to the polarity of solvents. The magnitude of change in the dipole moment was calculated based on the Lippert-Mataga equation. DBBA has an increase of dipole moment of 4.9 D units on excitation to the lowest singlet state. A high fluorescence quantum yields (ϕf) and short fluorescence decay times (τf) were determined in all solvents tested. The bathochromic shift of the emission spectra and the increase in the excited state dipole moment occurred. These gave the evidence about the intramolecular charge transfer (ICT) character in the emitting singlet state of DBBA.