Fluorescent substituted amidines of benzanthrone: Synthesis, spectroscopy and quantum chemical calculations

Several new substituted amidine derivatives of benzanthrone were synthesized by a condensation reaction from 3-aminobenzo[de]anthracen-7-one and appropriate aromatic and aliphatic amides. The obtained derivatives have a bright yellow or orange fluorescence in organic solvents and in solid state. The novel benzanthrone derivatives were characterized by TLC analysis, 1H NMR, IR, MS, UV/vis, and fluorescence spectroscopy. The solvent effect on photophysical behaviors of these dyes was investigated, and the results showed that the Stoke’s shift increased, whereas quantum yield decreased with the growth of the solvent polarity. The structure of some dyes was confirmed by the X-ray single crystal structure analysis. AM1, ZINDO/S and ab initio calculations using Gaussian software were carried out to estimate the electron system of structures. The calculations show planar configurations for the aromatic core of these compounds and two possible orientations of amidine substituents. The calculation results correlate well with red-shifted absorption and emission spectra of compounds.

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► A series of novel benzanthrone dyes containing amidino group were synthesized and characterized.
► Spectroscopic properties of the new molecules were examined by FT-IR, NMR and UV techniques.
► Solvatochromic effect was studied. X-ray crystal structures were determined.
► HOMO and LUMO energies, molecular electrostatic potential distribution and dipole moments were calculated.