Solvothermal synthesis and structures of lanthanide-organic sandwich coordination polymers with 4,40-biphenyldicarboxylic acid

First examples of lanthanide coordination polymers with 4,40-biphenyldicarboxylic acid (4,40-H2bpdc), Ln(4,40-Hbpdc)(4,40-bpdc)(H2O)2 (Ln ¼ Pr(1), Eu(2), Gd(3)) and Er(4,40-bpdc)1.5(H2O)2 (4) were prepared by the solvothermal synthesis. Crystallographic data show that complexes 1–3 are isostructural and each lanthanide(III) ion is coordinated to six 4,40-Hbpdc ligands, and display 3D sandwich structure with lanthanide ion layers and organic ligand layers alternately linking up with each other. Complex 4 shows different coordination modes of 4,40-bpdc ligands from 1–3 and each Er(III) ion is attached to four 4,40-bpdc ligands to construct 3D sandwich structure. The emission spectrum of 2 shows one Eu3þ ion site, which is consistent with the results of the X-ray crystal structure analysis. q 2004 Elsevier B.V. All rights reserved