Facile Synthesis of Nitrogen-Containing Six-Membered Benzofuzed Phenophosphazinine Oxides and Studies of the Photophysical Properties

A facile synthesis of nitrogen-containing six-membered benzofuzed phosphacycles has been described. This cyclization reaction triggered by Tf2O provides an expedient protocol of phosphacycles with a simple operation at mild conditions. The preliminary photophysical studies of these novel materials reveal that the fluorescence intensity enhances with the molecular aggregation in the solid state and that the introduction of the sterically bulky phenanthrene group into the phosphacycles allows a significant increase in the fluorescence quantum yield.