Abstract The title compound N, N-bis(2,5-dioxopyrrolidin-1-ylmethyl)-γ-amino-butyric acid (DOPMABA) was synthesized through the Mannich reaction of succinimide with γ-amino-butyric acid in the formaldehyde solution. The structure and the fragments of DOPMABA were determined by single crystal X-ray diffraction and electrospray ionization mass spectrometry (ESIMS), respectively. The title compound has two kinds of configurations because of the long chain of γ-amino-butyric acid. The ternary Eu 3+ system with DOPMABA and 1,10-phenanthroline (phen) shows good photochromism in aqueous medium. Its decoloration process was investigated. Based on the decoloration curve, its E-diagram was obtained which displays that the decoloration is an independent step.