Polychrome luminescence and photochromic transformations in anthrone solutions

Abstract

Polychrome luminescence was observed in the UV irradiation of an aerated anthrone solution in ethanol or isopropanol: the initially blue luminescence of the solution changed to indigo blue and then to green. Simultaneously with the luminescence changes, the colorless solution became yellow. The appearance of green luminescence was preceded by a period during which the solution almost did not luminesce. It was found that the photooxidation of ethanol (isopropanol) with oxygen sensitized by anthrone (KH) occurred during irradiation. Green luminescence appeared at the time when the concentration of dissolved oxygen decreased below a critical value. The green luminescence spectrum with a maximum at 495 nm and a shoulder at ∼475 nm was ascribed to the oxonium form of anthrone (KH 2 + ). The possibility of using the oxygen quenching of the green fluorescence of anthrone solutions for analytical purposes and the use of the anthrone-sensitized photooxidation of ethanol with oxygen for the deoxygenation of solutions in laboratory practice are discussed.