Cao, Xin-Yi, Yao, Yuan-Gen, Batten, Stuart R., Ma, EN, Qin, Ye-Yan, Zhang, Jian, Zhang, Rui-Bo, and Cheng, Jian-Kai
Three novel luminescent metal–organic frameworks [Zn(1,2-BBOMB)(4,4′-bipy)1/2]n(1), [Zn2(1,3-BBOMB)2(4,4′-bipy)]n(2) and [Zn4(1,2-BBOMB)4(bpp)2]n(3) have been synthesized by combining the conformationally flexible V-shaped long multicarboxylate ligands and the rigid 4,4′-bipy or flexible bpp ligands with zinc ions under hydrothermal conditions. It is worth mentioning that the layers observed in the three compounds can be reduced to the same 6-connected topological net with (22·48·65) symbol. These complexes display a structural evolution from a two-dimensional (2D) polyrotaxane and polycatenane framework to a three-dimensional (3D) architecture with coexistence of polyrotaxane, polycatenane and interdigitation. The three species contain loops and rods that are interlaced in a highly rare parallel fashion, but with twofold (2D → 2D), triply (2D → 2D) and triply (2D → 3D) entangled features in complexes 1, 2and 3, respectively. Furthermore, the rotaxane-like interactions between the loops and the rods exhibit a progressive change from one loop interacting with a single rod, to one loop interacting with two identical rods, to finally one loop interacting with two conformationally different rods in complexes 1, 2and 3, respectively. Photoluminescence studies revealed that these complexes are potential violet, blue and green luminescent materials. The thermal stabilities of these complexes were also discussed. [ABSTRACT FROM AUTHOR]