Novel Zinc Phosphate Topologies Defined by Organic Ligands

Six new zinc phosphates [C18H20N4][Zn4(HPO4)4(H2PO4)2(C18H18N4)3]·2H2O (1), [Zn4(HPO4)4(C18H18N4)3]·4H2O (2),
[Zn3(HPO4)3(H2PO4)(C22H22N8)0.5(C22H24N8)0.5] (3), [Zn2(HPO4)2(C18H16N4)] (4), [Zn(HPO4)(C18H14N2)] (5), and [Zn2(HPO4)2(C12H10N4)] (6) have been synthesized under mild hydrothermal conditions in the presence of 1,4-bis(N-benzimidazolyl)butane (L1), 1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene (L2), 1,4-bis(imidazol-1-ylmethyl)naphthalene
(L3), 9-(imidazol-1-ylmethyl)anthracene (L4), and 1,4-bis(1-imidazolyl)benzene (L5), respectively, and their structures
were determined by X-ray crystallography. Compound 1 exhibits a unique inorganic motif of isolated 8-rings
interconnected by L1. Compound 2, also formed from L1, contains a previously unobserved chain structure composed
of edge-sharing 4-rings and 8-rings. Compound 3, prepared from L2, possesses an unusual one-dimensional
framework, which is composed of vertex-sharing 4-rings and triple fused 4-rings. The inorganic portions of 4, 5,
and 6 each adopt a layer structure. The sheets in 4 and 5 have a 4.82 topology, and in 6, a 63 topology is
observed. The zinc atoms in compounds 1−6 are all tetrahedrally coordinated by a combination of phosphate
groups and organic ligands. Potential relationships between the inorganic motifs reported in the present study are
identified. These are indicative of a possible pattern of self-assembly of zinc and phosphorus tetrahedra and indicative
of the role of the organic ligands in the formation of hybrid structures.