2-Acyl-1,1,3,3-tetracyanopropenides (ATCN): structure characterization and luminescence properties of ammonia and alkali metal ATCN salts

Herein, syntheses, crystal structures, and photoluminescence properties of 24 new ammonia and alkali metal ATCN salts characterized via single-crystal X-ray diffraction are reported. Moreover, ten structure types of these salts have been described, three of which are predominant. Some ATCNs were obtained as two crystalline polymorphs. It was estimated that most ATCN powders exhibited yellow-green fluorescence (at 450-600 nm). For samples that possess fluorescence of low intensity in the solid state, several optical centers of emission exist. It was speculated that the obtained spectral features were due to anion-anion intermolecular interactions. ATCN being a new representative of stable tetracyanoallyl salts is a promising candidate for creation of various 1D, 2D, and 3D supramolecular structures and potential functional materials.