Hydrothermal synthesis, crystal structure and luminescence of a europium complex with phenylmalonic acid and 1, 10-phenanthroline

A new complex Eu2(PA)6(phen)2 was prepared with hydrothermal reaction using EuCl3-6H2O, phenylmalonic acid (H2phma), and 1, 10-phenanthroline (phen), where PA was the decarboxylated product of H2phma, phenylacetate. The crystal structure of the title complex was determined with the X-ray diffraction. The title complex was a binuclear molecule with an inversion center. Each Eu3+ ion was nine-coordinated with two nitrogen atoms from one phen molecule and seven oxygen atoms from five PA ligands. The carboxylic groups were bonded to the Eu3+ ion in three modes, the chelating bidentate, the bridging bidentate, and the bridging-chelating tridentate. The complex emits intense red fluorescence under ultraviolet light. The luminescence peaks correspond to the characteristic emission 5D0 7Fj (J=0-4) transitions of the Eu3+ ion.