TY - JOUR A1 - Breuer, Natascha A1 - Gruber, Irina A1 - Janiak, Christoph A1 - Müller, Thomas J. J. T1 - Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences JF - Beilstein Journal of Organic Chemistry PY - 2019/// VL - 15 SP - 2684 EP - 2703 SN - 1860-5397 DO - 10.3762/bjoc.15.262 PB - Beilstein-Institut JA - Beilstein J. Org. Chem. UR - https://doi.org/10.3762/bjoc.15.262 KW - cyclocondensation KW - DFT calculations KW - fluorescence KW - heterocycles KW - 1H-pyridines KW - α-pyrones N2 - Starting from substituted alkynones, α-pyrones and/or 1H-pyridines were generated in a Michael addition–cyclocondensation with ethyl cyanoacetate. The peculiar product formation depends on the reaction conditions as well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular, dimethylamino-substituted α-pyrones, as donor–acceptor systems, display remarkable photophysical properties, such as strongly red-shifted absorption and emission maxima with daylight fluorescence and fluorescence quantum yields up to 99% in solution and around 11% in the solid state, as well as pronounced emission solvatochromism. Also a donor-substituted α-pyrone shows pronounced aggregation-induced emission enhancement. ER -