On the photo-oxidation of perylene bisimide dyes in alcoholic solutions

Abstract Irradiation with intense blue LED light of Lumogen orange 240 ( 1 ) in non-reactive solvents led to bleaching. The products of these photochemical reactions were not possible to determine. Contrarily, irradiation in ethanol or propanol led to red color shifts caused by the formation of the ethoxy or propoxy derivative of Lumogen orange 240, respectively. These new reaction products are only formed when both light and oxygen are present. A possible mechanism for these photo-oxidation reactions, the implication for the stability of perylene type of fluorescent dyes under LED lamp conditions and possible preparative applications are discussed.