Hydrothermal synthesis, structures, and photoluminescent properties of benzenepentacarboxylate bridged networks incorporating zinc(II)-hydroxide clusters or zinc(II)-carboxylate layers

The first coordination compounds of partially or wholly deprotonated benzenepentacarboxylic acid (H5L) were synthesized in the presence or absence of auxiliary 2,2'-bipyridyl (2,2'-bpy) and 1,10-phenanthroline (phen) ligands, and their crystal structures and photoluminescent properties were characterized. Their formulas are [Zn-6(mu(3)-OH)(2)(L)(2)(H2O)(6)](n) 1 (1), [Zn-5(mu(3)-OH)(2)(HL)(2)(2,2'-bPY)(2)](n) (2), [Zn-2(HL)(phen)(2)(H2O)(2)](n) (3), and [Zn-5(L)(2)(phen)(4)(H2O)(3)](n)center dot 2nH(2)O (4). Both 1 and 2 are three-dimensional (3D) zinc(II)-hydroxide cluster based coordination frameworks. 1 contains distorted chairlike hexanuclear Zn-6(mu(3)-OH)(2) cluster units as secondary building blocks. Each Zn-6(mu(3)-OH)(2) unit connects six others through the three-connected nodes of L5- ligands into a 3D rigid and condensed coordination network, whereas in 2, each pentanuclear Zn-5(mu(3)-OH)(2) unit connects the other six ones through the three-connected [HL](4-)nodes into a 3D network in the simple cubic packing mode. 3 has two-dimensional (2D) Zn(II)-carboxylate supramolecular layers constructed from a one-dimensional (1 D) coordination chain structure by hydrogen bonds of the water and mu(5-)[HL](4-) bridges, whereas 4 has 2D coordination layers composed of Zn(II) and mu(8)-L5- bridges. The adjacent coordination assemblies in 3 and 4 are further extended by hydrogen bonds and pi center dot center dot center dot pi interactions into 3D supramolecular architectures. 1-4 are photoluminescent active materials, and their photofluorescent properties are closely related to their intrinsic structure arrangements.