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

Reactions of 1,4-naphthalenedicarboxylic acid (1,4-H(2)nda) and a bent dipyridyl co-ligand 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4bpt) with Co-II, Zn-II, or Cd-II 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 {[Cd-2(1,4-nda)(2)(4bpt)(2)(H2O)(2)](DMF)(1.5)(H2O)(3)}(n) (4). In the structure of the Co-II 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 Co-II 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 Zn-II complex 3 is isostructural to 2, and the Cd-II complex 4 displays a 2-fold parallel interpenetrating array of undulating (4,4) coordination layers. By using the conventional solvent evaporation method, two Pb-II naphthalenedicarboxylates [Pb(1,4-nda)(DMF)](n) (5) and {[Pb-2(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 Zn-II, Cd-II, and Pb-II complexes have also been explored. (C) 2009 Elsevier Ltd. All rights reserved.