Synthesis, structure and properties of three 1D d10 metal–organic coordination polymers with 5-amino-2,4,6-triiodoisophthalic acid

Abstract

The work presents an further investigation on the coordination chemistry of 5-amino-2,4,6-triiodoisophthalic acid (H2ATIBDC) and reveals the significant function of weak interactions in constructing the resultant supramolecular networks. Reactions of H2ATIBDC with the d10 metal ions [Zn(II) and Cd(II)] in the presence of varied N-donor auxiliary imidazole ligands at ambient condition yield three new 1D metal–organic coordination polymers (CPs): {[Cd(ATIBDC)(biim)]·2H2O}n (1), {[Zn(ATIBDC)(biim)]·3H2O}n (2) and [Cd(ATIBDC)(bbi)]n (3) [biim=2,2′-biimidazole, bbi=1,1′-(1,4-butanediyl)bis(imidazole)], which are characterized by elemental analysis, IR spectroscopy, thermogravimetry and single crystal X-ray diffraction measurements. Generally, these three complexes display 1D ATIBDC2−-bridged coordination arrays. Extended 3D supramolecular network architectures are further constructed through the weak secondary interactions: aromatic stacking, halogen bonding and hydrogen bonding. It should be interesting to emphasize that the C–I…π halogen bonding plays significant role in the supramolecular assembly of 3. An acyclic trimeric water cluster (D3 chain) was observed and discussed in 2. Thermal stabilities of 1, 2 and 3 have been studied. The fluorescent properties of 1, 2 and 3 have been investigated in the solid state. Compounds 1 and 2 show completely reversible dehydration–rehydration behaviors, which reveal that 1 and 2 may possibly be used as water adsorbents.