Solid chemistry of the ZnII/1,2,4-triazolate/anion system: Separation of 2D isoreticular layers tuned by the terminal counteranions X (X=Cl−, Br−, I−, SCN−)

An array of 2D isoreticular layers, viz. [Zn(atrz)X]∞ (1·X; X=Cl−, Br−, I−; atrz=3-amino-1,2,4-triazole anion), [Zn4(atrz)4(SCN)4·H2O]∞ (1·SCN·H2O) and [Zn(trz)X]∞ (2·X; X=Cl−, Br−, I−; trz=1,2,4-triazole anion), have been hydrothermally synthesized and structurally characterized. Compounds 1·X and 1·SCN·H2O are constructed from binuclear planar Zn2(atrz)2 subunits and exhibit (4,4) topological network when the subunits are simplified as four-connected nodes. Based on changing the terminal counteranions X (X=Cl−, Br−, I−, SCN−), the average interlayer separations of 1·X and 1·SCN·H2O are enlarged, which equal to 5.851, 6.153, 6.651 and 8.292 Å, respectively. As a result, H2O molecules reside in the spaces between two adjacent layers of 1·SCN·H2O. 2 and 1 are the isomorphous structures. In common with 1, the interlayer separations of 2·X are widened with increasing the ion radius. Solid-state luminescence properties and thermogravimetric analyses of 1 and 2 were investigated, respectively.