Metal naphthalenedicarboxylates with diverse network architectures: Synthesis, crystal structures and properties

Reactions of 1,4-naphthalenedicarboxylic acid (1,4-H2nda) and a bent dipyridyl co-ligand 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4bpt) with CoII, ZnII, or CdII acetate afford four coordination polymers, [Co(1,4-nda)(4bpt)(H2O)]n (1), {[Co(1,4-nda)2(4bpt)(H2O)2][Co(4bpt)(H2O)4](H2O)1.5}n (2), {[Zn(1,4-nda)2(4bpt)(H2O)2][Zn(4bpt)(H2O)4](H2O)1.5}n (3), and {[Cd2(1,4-nda)2(4bpt)2(H2O)2](DMF)1.5(H2O)3}n (4). In the structure of the CoII complex 1, the polycatenation of inclined 2-D (4,4) coordination layers leads to the formation of a 3-D supramolecular framework, whereas two types of 1-D polymeric chains are observed in another CoII coordination species 2, which are interconnected via H-bonding to result in an unusual 3-D host–guest lattice. Notably, complexes 1 and 2 have been prepared under similar hydrothermal conditions and their structural discrepancy can only be ascribed to a subtle change of basicity for the reaction solution. The ZnII complex 3 is isostructural to 2, and the CdII complex 4 displays a 2-fold parallel interpenetrating array of undulating (4,4) coordination layers. By using the conventional solvent evaporation method, two PbII naphthalenedicarboxylates [Pb(1,4-nda)(DMF)]n (5) and {[Pb2(2,6-nda)2(DMF)2](DMF)}n (6) have also been prepared (2,6-nda = 2,6-naphthalenedicarboxylate). Complex 5 has a unique 5-connected 3-D coordination architecture, whereas 6 represents a 3-fold interpenetrating framework of 4-connected diamond topology. Their structural difference suggests the significant isomeric effect of the naphthalenedicarboxylate tectons on structural assemblies. Thermal stability of these crystalline materials has been investigated by thermogravimetric and differential thermal analysis (TG–DTA) technique and solid-state luminescent properties of the ZnII, CdII, and PbII complexes have also been explored.

A series of metal–naphthalenedicarboxylate coordination frameworks with interesting network structures have been presented and their solid-state properties such as thermal stability and fluorescence have also been investigated.Figure optionsDownload as PowerPoint slide