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 [Zn6(μ3-OH)2(L)2(H2O)6]n (1), [Zn5(μ3-OH)2(HL)2(2,2‘-bpy)2]n (2), [Zn2(HL)(phen)2(H2O)2]n (3), and [Zn5(L)2(phen)4(H2O)3]n·2nH2O
(4). Both 1 and 2 are three-dimensional (3D) zinc(II)−hydroxide cluster based coordination frameworks. 1 contains
distorted chairlike hexanuclear Zn6(μ3-OH)2 cluster units as secondary building blocks. Each Zn6(μ3-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 Zn5(μ3-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 (1D) coordination chain structure by hydrogen bonds of
the water and μ5-[HL]4- bridges, whereas 4 has 2D coordination layers composed of Zn(II) and μ8-L5- bridges.
The adjacent coordination assemblies in 3 and 4 are further extended by hydrogen bonds and π···π interactions
into 3D supramolecular architectures. 1−4 are photoluminescent active materials, and their photofluorescent properties
are closely related to their intrinsic structure arrangements.