Three Acentric Cu(II) D-(–)-quinate Complexes: Solvent-Dependent Assemblies, Magnetic and Ferroelectric Properties.

Reaction of copper salts and D-(–)-quinic acid (H5L) yielded three complexes, [Cu(H2O)(H3L)]2·2H2O1, [Cu(H2O)(H4L)(NO3)]n·(H2O)n2, and [Cu(H2O)(H4L)(ClO4)]n·(2H2O)n3. An interesting law was observed that solvent selection influenced the structural assemblies, namely, in an aqueous solution utilizing CuCl2·2H2O/Cu(NO3)2·6H2O/Cu(ClO4)2·6H2O and D-(–)-quinic acid only obtained [Cu(H2O)(H3L)]2·2H2O1,while the environment was replaced by an alcoholic system, afforded three polymers: [Cu(H2O)(H4L)Cl]n·(H2O)n4, [Cu(H2O)(H4L)(NO3)]n·(H2O)n2, and [Cu(H2O)(H4L)(ClO4)]n·(2H2O)n3, respectively. Complex1crystallizes in the polar monoclinicC2 space group, while complexes2and3in the nonpolar orthorhombic space groupP212121. In compound1, the binuclear Cu(II) units are assembled into 3D network through hydrogen bonds and the overall topology can be described as a 7-connected dinodal net topology of (36·48·57) with the Schläfli symbol of (3.3.3.3.3.3.4.4.4.4.4.4.4.4.5.5.5.5.52.52.52). In2and3, the D-(–)-quinic acid anions are function as tetradentate ligands bridging Cu(II) ions to build up 3D metal-organic frameworks (MOFs) with {103} topological representation. The polar complex1displays a promising ferroelectricity with a remnant polarization (Pr) ofca.0.07 μC/cm2, coercive field (Ec) ofca.2.43 kV/cm, and saturation of the spontaneous polarization (Ps) ofca.0.128 μC/cm2. The magnetic behavior of1suggests significant antiferromagnetic coupling interactions between Cu(II) ions bridged by carboxylic groups, while considerable ferromagnetic coupling interactions in complexes2and3. Furthermore, the title complexes1–3were subjected to microelement analyses, IR spectroscopic measurements, and thermal analyses. [ABSTRACT FROM PUBLISHER]