Solvatochromic study of 3-N-(N'-methylacetamidino)benzanthrone and its interaction with dopamine by the fluorescence quenching mechanism.

The change in photophysical properties of the organic molecule due to solvatochromic effect caused by different solvent environments at room temperature gives information about the dipole moments of 3-N-(N'-methylacetamidino)benzanthrone (3-MAB). The quantum yield, fluorescence lifetime of 3-MAB was measured in different solvents to calculate radiative and non-radiative rate constants. The results revealed that the excited state dipole moment (μe ) is relatively larger compared to the ground state dipole moment (μg ), indicating the excited state of the dye under study is more polar than the ground state and the same trend is noticed with theoretical calculations performed using the CAM-B3LYP/6-311+G(d,p) method. Further, the study on preferential solvation was carried out for 3-MAB dye in ethyl acetate-methanol solvent mixture. The fluorescence quenching method has been employed for the detection of dopamine using 3-MAB as fluorescent probe, using steady-state and time resolved methods at room temperature. The method enables dopamine in the micro molar range to be detected. Also, an attempt to verify the quenching process by employing different models has been tried. Various rate parameters are measured using these models, our results indicates the quenching process is diffusion limited.