Positional isomeric effect of phenylenediacetate on the construction of mixed-ligand CdII coordination frameworks

Three CdII coordination polymers merging two types of flexible ligands, phenylenediacetate isomers (o/m/p-pda = 1,2/1,3/1,4-phenylenediacetate) and 1,4-bis(imidazol-1-ylmethyl)benzene (bix), have been hydrothermally synthesized and characterized. [Cd(o-pda)(bix)]n (1) and [Cd(m-pda)(bix)0.5(H2O)]n (2) have 2D coordination networks containing hetero-helical subunits, in which 1 features a (3,5)-connected (42.6)(42.67.8) topology, but 2 shows a (3,4)-connected V2O5-type net with (42·6)(42·63·8) topology. Different from 1 and 2, [Cd(p-pda)(bix)]n (3) displays a 5-fold interpenetrating dia framework, indicating structure-directing effect of the positions of acetate groups in pda.