Coordination assemblies of the MII-tm/bpt (M = Zn/Cd/Co/Ni) mixed-ligand system: positional isomeric effect, structural diversification and properties†
Abstract
To further investigate the influence of the positional isomeric ligands on structural topologies, six new coordination polymers with three positional isomeric dipyridyl ligands (4,4′-Hbpt, 3,4′-Hbpt and 3,3′-Hbpt) and trimellitic acid (H3tm), namely, {[Zn3(tm)2(4,4′-Hbpt)2(H2O)2]·10H2O}n (1), [Zn3(tm)2(3,3′-Hbpt)2]n (2), {[Cd2(tm)(3,4′-bpt)(H2O)2]·H2O}n (3), {[Cd4(tm)2(3,3′-bpt)2(H2O)2]·3H2O}n (4), {[Co3(tm)2(3,4′-Hbpt)2(H2O)6]·2H2O}n (5), {[Ni3(tm)2(3,3′-Hbpt)4(H2O)2]·7H2O}n (6), have been synthesized under hydrothermal conditions and characterized. Structural analysis reveals that: 1 and 5 both have 3D 4-connected networks, with the (4.64.8)(42.63.8)2(44.62)2 Schläfli symbol for 1 and (42.52.72)(52.62.7.8)2(4.52.6.72)2 symbol for 5. 2 and 3 both have 3D (4,5)-connected networks, with the (34.42.52)2(42.84)(3.43.52.6.72.8)2 symbol for 2 and (34.42.52)2(42.84)(3.43.52.6.72.8)2 symbol for 3. 4 has a 3D trinodal (3,4,5)-connected net with the (3.44.53.6.7) (43.62.7)(44.62)(42.6)2(45.64.8)2 symbol. And 6 has a 2D (3,4)-connected layer with (3.62)2(3.4.62.72)2(5.63.82) symbol. These results indicate that the versatile coordination modes of tm and the isomeric nature of bpt play crucial roles in modulating structural topologies of these complexes. Moreover, the luminescent properties of 1–4 and the magnetic behavior of 5–6, have been investigated.