Three Zn(II) metal-organic frameworks assembled from a versatile tecton 5-ethyl-pyridine-2,3-dicarboxylate and dipyridyl-type coligand

Solvothermal reactions of 5-ethyl-pyridine-2,3-dicarboxylic acid and dipyridyl-type ligands with Zn (Ac)(2)center dot 2H(2)O afford three metal-organic frameworks, including {[Zn-2(EPDA)(2)(BPP)(2)]center dot(H2O)}(n)(1), [Zn-3(EPDA)(2)(HEPDA)(2)(BPE)](n) (2) and [Zn-3(EPDA)(2)(HEPDA)(2)(BPA)](n) (3) (H(2)EPDA = 5-ethyl-pyridine-2,3-dicarboxylic acid, BPP = 1,3-di(4-pyridyl)propane, BPE = 1,2-di(4-pyridyl)ethylene and BPA = 1,2-bi(4-pyridyl)ethane). The pronounced structure for 1 represents a rare 2D -> 3D interpenetrated framework with new layer motif featuring a 4-connected net signified as Schlafli symbol of (3.6(4).8)(3(2).6.7(2).8). Complexes 2 and 3 possess intimately related structures featuring infinite Zn carboxylate layers of [Zn-3(EPDA)(2)(HEPDA)(2)](n) pillared by a BPE (or BPA) molecule to produce the three-dimensional frameworks with pcu topology based on the Zn trimers as the 6-connected nodes. It is shown that the flexible degree of dipyridyl-type molecules plays a key role for the assembly of diversified coordination networks. Furthermore, thermal degeneration and fluorescence properties of all three complexes are also investigated.