Temperature-controlled assembly of two fluorescent ZnII polymers from 3D pillared-layer framework to 2D (4, 4) layer

Two ternary coordination polymers with the same ingredients but different structures, [Zn2(datrz)2(nip)]n (1) and {[Zn(Hdatrz)(nip)]·H2O}n (2) (Hdatrz = 3,5-diamino-1,2,4-triazole; nip2− = 5-nitroisophthalate), were respectively obtained by temperature-controlled hydrothermal reactions and fully structural characterized. Interestingly, tetrahedral ZnII ions in 1 are linked into wavy layers by anionic μ3-N1,N2,N4-datrz ligands, which are further supported by deprotonated bis-monodentate nip2− to generate a 3D pillared-layer framework. In contrast, the tetrahedral ZnII ions in 2 are aggregated into a (4, 4) covalent layer through alternate μ2-N1,N4-Hdatrz and bis-monodentate nip2− bridges. Thus, the competitive binding of the two polydentate ligands to the metal ion plays essential roles on the connectivity and dimensionality of the two complexes. Thermal stability and the fluorescent emissions of the two complexes were also investigated and compared.