Assemblies of several supramolecular networks containing quinoline-2,3-dicarboxylic acid

At low temperature, the reactions of quinoline-2,3-dicarboxylic acid (2,3-H2qldc) with ZnCl2 in three different solvents gave three 0-D mononuclear compounds respectively, namely Zn(2,3-Hqldc)2(H2O)2 (1), Zn(2,3-Hqldc)2(DMSO)2 (2) and Zn(2,3-Hqldc)2(H2O)2·C6H6 (3). At high temperature, the three corresponding reactions always produced 2-D 44 topological layer [Zn(2,3-Hqldc)2]n (4). Interestingly, compound 4 may also be constructed through the temperature-driven irreversible change in solution from 1, 2 and 3. Supramolecular structure analyses reveal that through hydrogen bonding interactions, such as O–H⋯O/C–H⋯O)/C–H⋯π/π⋯π, the mononuclear units Zn(2,3-Hqldc)2(H2O)2 (1), Zn(2,3-Hqldc)2(DMSO)2 (2) and Zn(2,3-Hqldc)2(H2O)2·C6H6 (3) as well as the 2-D layer [Zn(2,3-Hqldc)2]n (4) were further assembled into 3-D 412·63 (in 1 and 4) and 3-D 424·64 (in 2 and 3) supramolecular networks, respectively. Obviously, these results show that the reaction temperature and solvent play critical roles in directing the molecular structures and supramolecular assemblies of these low-dimensional zinc(II) compounds.