9,10-Anthracenediyl-bis(methylene)dimalonic acid

9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA) is a biological dye and indicator used to detect singlet oxygen generation (SOG). 9,10-Anthracenediyl-bis(methylene)dimalonic acid can be photobleached by singlet oxygen to its corresponding endoperoxide. This reaction can be monitored spectrophotometrically by recording the decrease of absorbance at 400 nm.