Molecular mechanism of the solid-state fluorescence behavior of the organic pigment yellow 101 and its derivatives

Close and yet fluorescent: Derivatives of Pigment Yellow 101 can exhibit small intermolecular distances in the solid-state crystal structures. Nevertheless, these compounds show strong solid-state fluorescence. X-ray structure determinations and elaborate quantum-chemical calculations indicate that the unexpected fluorescence is a property of the individual molecules which is retained in the crystal. (Excited state energies are plotted along a CNN bending mode.) (Graph Presented). © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.