Hydrothermal Crystallization of Three Calcium-Based Hybrid Solids with 2,6-Naphthalene- or 4,4′-Biphenyl-Dicarboxylates

Abstract

Three new hybrid solids 1, 2, and 3 of calcium dicarboxylates have been obtained using hydrothermal conditions (24 h, 180 °C) with 2,6-naphathalenedicarboxylic acid (H2ndc) and 4,4′-biphenyldicarboxylic acid (H2bpdc) ligands. According to their single-crystal X-ray diffraction analyses, the three compounds exhibit dense networks with distinct dimensionalities for both the inorganic subnetwork and the whole structure. Three-dimensional (3D) 1 (Ca2(OH)2[ndc]) is built from layers of calcium oxo-hydroxide, pillared via the ndc ligands. Calcium is 7-fold coordinated with a monocapped trigonal prismatic surrounding (CaO4(OH)3). In 2 (Ca(H2O)[bpdc]), the structure consists of infinite chains of calcium polyhedra in a pentagonal bipyramidal coordination (CaO6(H2O) unit), the biphenyldicarboxylate species acting as scaffolds for the 3D structure. Complex 3 (Ca(H2O)3[bpdc]) also contains infinite chains of calcium polyhedra (with 8-fold coordination - CaO4(H2O)4 unit) but this time isolated because one of the two carboxylate functions of the ligand is terminal. The structure is therefore one-dimensional. A network of hydrogen bonds ensures the stability of this structure. Crystal data for 1: monoclinic, P21/c, a = 12.627(2), b = 7.8053(13), c = 5.8555(10) Å, β = 95.954(3)°, and V = 573.97(17) Å3; for 2: monoclinic, P21, a = 5.8237(4), b = 6.9339(5), c = 14.7231(11) Å, β = 93.588(3)°, and V = 593.37(7) Å3; for 3: orthorhombic, Ima2, a = 6.5444(3), b = 30.2468(13), c = 7.2194(3) Å, and V = 1429.06(11) Å3.