Crystal structure and luminescence of a europium nitrate complex with furancarboxylic acid and 2,2′-bipyridine

A quaternary mixed ligand europium complex, [Eu(FA)(2)NO(3)bipy](2), has been synthesized, where FA = alpha-furancarboxylic acid anion and bipy = 2,2'-bipyridine. The europium complex crystallizes in the triclinic system, space group <P(1)over bar>. Its structure was determined by X-ray diffraction methods. The two europium ions in the dimer are held together by four carboxylate groups of furancarboxylic acid and each europium ion is further bonded to one chelated bidentate nitrate and one 2,2'-bipyridine molecule. The coordination modes of the four carboxylate groups are divided into two types, bidentate bridging and tridentate bridging, making a coordination number of 9. Excitation and luminescence spectra observed at 77 K show that the europium ion site in the crystal has low symmetry and emission D-5(1) --> F-7(J) of the Eu3+ ion disappears after 20 mu s.