Structural and luminescence characterizations of lanthanide-based coordination polymers involving naphthalene-1,4,5,8-tetra-carboxylate as ligand

• The compounds have been obtained by green chemistry routes.
• In one crystal structure 2D and 1D molecular motifs alternate.
• One of the crystal structures can be described as a co-crystallization of the two others.

Reactions in water between lanthanide ions and the sodium salt of naphthalene-1,4,5,8-tetra-carboxylic acid lead to three families of coordination polymers as microcrystalline powders and/or single crystals. Their respective chemical formulae are {[Ln(ntc)(H2O)5][Ln(H2O)10]1/3,3H2O}∞ with Ln = Ce, Gd or Eu (family 1), [NaYb(ntc)(H2O)6,4H2O]∞ (family 2), and [Ln2(ntc)1.5(H2O)11,9H2O]∞ with Ln = Dy–Er and Y (family 3). The crystal structure of family 1 has been solved on the basis of the Ce-containing compound. This compound crystallizes in the monoclinic system, space group C2/c (n°15) with a = 32.2307(6) Å, b = 6.6168(1) Å, c = 22.4244(4) Å, β = 91.814(1)°, V = 4779.92(14) Å3 and Z = 4. The only compound that constitutes family 2 crystallizes in the monoclinic system, space group C2/c (n°15) with a = 6.3396(1) Å, b = 18.0440(2) Å, c = 19.6225(2) Å, β = 95.451(1)°, V = 2234.50(5)Å3 and Z = 4. The crystal structure of family 3 has been solved on the basis of the Er-containing compound. This compounds crystallizes in the monoclinic system, space group P21/a (n°14) with a = 22.0121(2) Å, b = 6.6973(1) Å, c = 26.4380(4) Å, β = 108.4469(4)°, V = 3697.27(9) Å3 and Z = 4. Its crystal structure can be described as a co-crystallization of the two others. Surprisingly, all these compounds present low-dimensionality while lanthanide-containing coordination polymers involving similar ligands, such as benzene-1,2,4,5-tetracarboxylate, show most often high dimensionality. The thermal behavior and the photo-luminescence properties of the compounds that belong to the third family have been studied.

Three families of lanthanide-containing coordination polymers involving naphthalene-1,4,5,8-tetra-carboxylate as ligand are structurally characterized. One of them presents a striking crystal structure in which 2D molecular motifs alternate with 1D molecular motifs. This study demonstrates that, despite its numerous potential coordination modes, naphthalene-1,4,5,8-tetra-carboxylate does not provide condensed crystal structures.Figure optionsDownload as PowerPoint slide