Predicting the modulation of UV–vis absorption and emission of mono-substituted pyrido[2,3,4-kl]acridines by electronic density variations analysis

•Pyrido[2,3,4-kl]acridines exhibit biological activities and fluorescent properties.•(TD)-DFT calculations accurately simulate UV–Visible absorptions and emissions of pyrido[2,3,4-kl]acridine.•Transition energies correlate with electronic density variation between the ground and the excited states.•Hammett parameter indicates accurately the influence of a substituent on spectroscopic properties.•The best substitution positions and the best substituents is achievable by extrapolation.