Exceptional self-penetrating networks containing unprecedented quintuple-stranded molecular braid, 9-fold meso helices, and 17-fold interwoven helices

摘要

Self-assembly of long V-shaped ligands and d(10) metal salts in the presence of a linear bidentate ligand affords two unprecedented self-penetrating coordination networks {[Zn-4(bptc)(2)(bpy)(4)]center dot(C5H3N)center dot 4H(2)O}(n) (1) and {[Cd-2(sdba)(2)(bpy)(H2O)(2)]center dot 2H(2)O}(n) (2) (bptc = 3,3',4,4'-benzophenonetetracarboxylate, sdba = 4,4'-sulfonyldibenzoate, bpy = 4,4'-bipyridine). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, X-ray powder diffraction, and TG analyses. 1 adopts a novel 3D framework containing three types of molecular braids, among which the quintuple-stranded molecular braid represents the highest-stranded molecular braid presently known for entangled systems. 2 is an uncommon self-penetrating 2D network containing pseudo-Borromean links and double-stranded helices. More interestingly, when the strong hydrogen bonds between layers are taken into account, the resulting net of 2 becomes an eight-connected 3D self-penetrating network with an unprecedented (4(21).6(7)) topology, which represents the highest connected topology presently known in self-penetrating systems. Furthermore, the photoluminescent properties of 1 and 2 were studied.