Self-assembly, reorganization, and photophysical properties of silver(I)-Schiff-base molecular rectangle and polymeric array species.

A self-assembly of AgClO(4) with a Schiff-base ligand N,N'-bis(pyridin-2-ylmethylene)benzene-1,4-diamine (1) gave a 1D zigzag polymeric array [[Ag(2)(C(18)H(14)N(4))(2)](ClO(4))(2)(CH(3)CN)](n) (3), while the self-assembly of AgClO(4) with 3,3'-dimethyl-N,N'-bis(pyridin-2-ylmethylene)biphenyl-4,4'-diamine (2) afforded the molecular rectangle [[Ag(2)(C(26)H(22)N(4))(2)](ClO(4))(2)] (4). The structures of 3 and 4 were characterized by single-crystal X-ray diffraction analysis. Structural data for 3 indicate that the Ag(I) ion is coordinated by two ligands of 1 in a distorted tetrahedral fashion thereby leading to a 1D zigzag polymeric array. The zigzag chains are interdigitated with weak pi-pi stacking interactions. The structure of 4 consists of a discrete molecular rectangle where the silver atom has a distorted square-planar coordination with the pyridyl ligands and azomethine nitrogen atoms of 2. An intramolecular pi-pi interaction between the phenyl rings of adjacent Schiff-base 2 functions to stabilize the rectangular architecture. The Ag(I)-Schiff-base coordination polymer 3 is not stable in solution. The degradation and reorganization of 3 to form a [2 x 2] grid architecture [[Ag(4)(C(26)H(22)N(4))(4)](ClO(4))(4)] (3g) was supported in a FAB-MS study. The rectangular structure of 4 remains intact in solution at ambient temperature. The complexes 3g and 4 exhibit unusual luminescence behavior in solution at room temperature with significantly red-shifted emission in the visible region.

Crystal engineering toward intersecting channels in a interpenetrated diamondoid network based on a net-to-net H-bonding interaction.

A thermally stable, four-fold interpenetrating diamondoid coordination network, Cd(imidazole-4-acrylate)2, with open intersecting channels within the interwoven nets, is strategically designed and synthesized on the basis of a spring-like net-to-net hydrogen-bonding interaction.

[Cd(II)(bpdc).H(2)O](n): a robust, thermally stable porous framework through a combination of a 2-D grid and a cadmium dicarboxylate cluster chain (H(2)bpdc = 2,2'-Bipyridyl-4,4'-dicarboxylic acid).

The synthesis and characterization of a cadmium(II) coordination polymer, [Cd(C(12)H(6)N(2)O(4)) x H(2)O](n)() (1), is reported. A single-crystal X-ray analysis shows that compound 1 presents a non-interpenetrating three-dimensional porous host containing one-dimensional hydrophilic channels, where guest water molecules reside. The strategy in designing the 3-D framework architecture is based on a combination of two building subunits: a porous two-dimensional grid of (4,4) topology and a metal dicarboxylate cluster chain. Both subunits are assembled from the coordination of a cadmium ion with a three-connecting organic modular ligand, 2,2'-bipyridyl-4,4'-dicarboxylic acid (H(2)bpdc). The results of thermogravimetric analysis and powder X-ray diffraction study show that the framework rigidity of compound 1 remains intact upon the removal of guest molecules, and maintains the thermal stability up to 440 degrees C. The second-row transition-metal ions are capable of engaging higher coordination modes (e.g., hepta- and octacoordination) because of their atomic sizes and intrinsic electron configurations. Our results show that the heptacoordinated cadmium center plays an important role in the overall framework rigidity and high thermal stability of compound 1. Crystal data for 1: Cd(C(12)H(6)N(2)O(4)) x H(2)O, triclinic, space group P1 macro, a = 6.7843(5) A, b = 9.3299(7) A, c = 9.4439(7) A, alpha = 104.629(1) degrees, beta = 92.324(1) degrees, gamma = 100.416(1) degrees, Z = 2.