Experimental and computational structural study of two hindered aminoanthraquinones in crystals and solutions

• Published in: Zeitschrift für Kristallographie. Crystalline materials Vol. 215; no. 9; pp. 542 - 546
• Main Authors: Yatsenko, A.V., Paseshnichenko, K.A., Popov, S.I.
• Format: Journal Article
• Language: English
• Published: De Gruyter Oldenbourg 01.09.2000
• ISSN: 2194-4946; 2196-7105
• DOI: 10.1524/zkri.2000.215.9.542

The crystal and molecular structures of 2-methyl-1-methylamino-anthraquinone (I) and 1-methylphenylamino-anthraquinone (II) were studied by the X-ray single-crystal diffraction and the visible spectra of crystalline specimens and their solutions were recorded. The molecule I is closely planar, whereas in the molecule II the amino group is 58° rotated out of the plane of the anthraquinone skeleton. In both structures the molecules pack in stacks. The comparison of experimental and calculated (on the DFT and AM1 levels) molecular structures, together with the comparison of experimental and INDO/S-calculated electronic spectra, give the evidence that molecular conformations (especially for II) change upon transfer from the solid state to solutions, and the π-delocalisation throughout the whole molecule enhances in the solid state.