Synthesis, crystal structure, hirshfeld surface analysis, spectroscopic, biological and first-principles studies of novel aminocoumarins

Two novel aminocoumarins 3-(1-(2 aminophenylamino) ethylidene)chromene-2,4-dione, noted (1) and 3-(1-(2-1-(2, 4-dioxochromene-3-ylidene) ethylamino)phenylamino) ethylidene) chromene-2,4-dione,noted (2), were synthesized from 3-acetyl-4-hydroxycoumarin and ortho-phenylenediamine in absolute ethanol and characterized by spectroscopies methods (FT-IR, UV-vis and fluorescence). The crystal structures of the mentioned compounds were solved from single-crystal diffraction data at low temperature. The compound (1) crystallizes in the orthorhombic system with space group Iba2 while (2) is monoclinic with space group P(2)1/c . Hirshfeld surface analysis indicates the presence of the pi-pi stacking in the aminocoumarin structures with the contribution of 7.8% for (1) and 8.7% for (2) of the total Hirshfeld area. The optimized DFT geometries (B3PW91/6-311 G (2df, p)) and the spectral simulations agree well with the experimental data. Theoretical reactivity behavior was assessed, taking into account HOMOLUMO diagrams and Molecular Electrostatic Potential maps. The two aminocoumarins derivatives have fluorescence properties. Analysis of the photoluminescence spectra shows that the emission intensity is high for the solutions of the two compounds in polar aprotic solvents (DMSO, DMF). The aminocoumarins were monitored for antimicrobial activity using the disk diffusion method. The coumarin (1) is effective against S. aureus (gram-positive bacteria) and S. typhy (gram-negative bacteria), but the coumarin (2) showed markedly weak antibacterial activity. (C) 2020 Elsevier B.V. All rights reserved.