Synthesis and photophysical properties of 7-(diethylamino)-3-(4-(arylethynyl)phenyl)-2H-chromen-2-ones as strong fluorescent materials

Abstract

3-(4-(Arylethynyl)phenyl)-7-(diethylamino)-2H-chromen-2-ones 1a‒1d were synthesized by Pd/Cu-catalyzed Sonogashira cross-coupling reactions. After the structural properties were examined by the X-ray crystal analysis, their photophysical properties including fluorescence properties in solid states were systematically studied. It was revealed that the pyrenyl derivative 1d showed high fluorescence quantum yield (ΦF = 0.87) in a THF solution, and that the phenyl derivative 1a exhibited an intense fluorescence (Φsolid = 0.15) even in a solid state. According to the TDDFT calculations, the HOMOs of compounds 1a and 1b are mainly located on the 3-(4-(arylethynyl)phenyl)-7-(diethylamino)-2H-chromen-2-one moieties, whereas on the aryl moieties for 1c and 1d. The electrochemical studies revealed that the compounds 1a and 1b underwent reversible 1e− oxidations.