New substituted azomethines of benzanthrone with heterocyclic substituents were synthesized by condensation reaction of 3-aminobenzo[de]anthracen-7-one with appropriate aromatic aldehydes. The resulting imines were reduced with sodium borohydride to the corresponding amines, the luminescence of which is more pronounced in comparison with the initial azomethines. The novel benzanthrone derivatives were characterized by NMR, IR, MS, UV/Vis, and fluorescence spectroscopy. The structure of three dyes was studied by the X-ray single crystal structure analysis. The solvent effect on photophysical behaviors of synthesized imines and amines was investigated. The obtained compounds absorb at 420–525 nm, have relatively large Stokes shifts (up to 150 nm in ethanol), and emit at 500–660 nm. The results testify that emission of the studied compounds is sensitive to the solvent polarity, exhibiting negative fluorosolvatochromism for the synthesized azomethines and positive fluorosolvatochromism for the obtained amines. The results obtained indicate that the synthesized compounds are promising as luminescent dyes.

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 (μ ) is relatively larger compared to the ground state dipole moment (μ ), 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.

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