Abstract: In the present paper, N,N-bis-(N-methylenesuccinimido) glycine(MSIG) was synthesized and characterized by elemental analysis, IR, ¹HNMR and MS. It is demonstrated by experiment that the europium complex of MSIG with 1,10-phenanthroline has reversible photochromism which occurs rarely in lanthanide complexes. Photochromic behavior of the europium complex was investigated in H₂O and H₂O-C₂H₅OH solvents. The irradiation of the europium complex solution led to a new absorption band with the maximum wavelength at ～616 nm while the color of the solution turned from yellow to green, and when the photolysate was kept in dark, the absorption spectrum turned to its initial figure. The results show that the spectral signal at ～616 nm appeared on irradiation and in general disappeared within 1h at ambient temperature. The yellow color of the europium complex solution turns green rapidly when irradiated as pHof the solution increases in a range of 46. On heating the color changes from green to yellow readily. The ab mismsorption spectra, the fluorescence spectra and the conductance measurement show that the europium ion is bonded to the carboxyl group of MSIG and the nitrogen atoms from 1,10-phenanthroline, and probably to water and hydroxyl group in the colored europium species.

Key words: Rare earths, N,N-Bis-(N-methylenesuccinimido)glycine, Ternary complex, Photochro