Alkali metal salts of a tetracyanopyridine (TCPy) derivative: structure characterization and luminescence properties

Abstract

Five new salts of the 3,4-dicyano-2-(dicyanomethylene)-5-methyl-6-phenyl-2H-pyridin-1-ide anion (TCPy⁻) with lithium, sodium, potassium, rubidium and cesium cations were synthesized and structurally characterized by a single-crystal X-ray diffraction method. The solid state photoluminescence characteristics of the prepared salts were studied. The crystallographic features of the crystal packing which are responsible for the emission band position were investigated. Quantum-chemical calculations were carried out to explain the correlation between emission maxima and the crystal structure.