Spectroscopic and photophysical properties of terbutaline

In this paper, we report the photophysical and spectroscopic properties of terbutaline in different solvents and under different acidic conditions. Theoretical calculations were also used to analyze the photophysical properties. It was found that terbutaline exhibits a characteristic absorption band in the range of 252-287 nm and two emission bands at 302 nm and 624 nm (ϕf =0.114, τ=14.9 ns). The nature of solvent was found to affect significantly the position of these bands as well as the fluorescence quantum yield which was found to be rather high in polar solvents. The fluorescence intensity of the cationic species was significantly quenched in the presence of strong acids such as H2SO4 and HCl, although the absorption and excitation band shape remained unchanged. Both steady state and time resolved fluorescence measurements show that the fluorescence quenching of terbutaline by acids is a dynamic process with quenching rate constants, kq, equal to 1.5×10^8 and 1.02×10^8 in sulfuric and hydrochloric acid, respectively.