Emission solvatochromic, solid-state and aggregation-induced emissive ?-pyrones and emission-tuneable 1H-pyridines by Michael addition-cyclocondensation sequences.

ABSTRACT: Starting from substituted alkynones, ?-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 ?-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 ?-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 ?-pyrone shows pronounced aggregation-induced emission enhancement.

SUBMITTER: Breuer N 

PROVIDER: S-EPMC6880829 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature