Positional isomeric effect on structural diversity of Zn(II) coordination polymers based on positional isomers and tetrahedral linker and pyridine-2,6-dicarboxylic acid

To systematically investigate the influence of the positional isomeric effect on the structures of their complexes, we prepared two Zn(II) complexes [Zn4(L1)(PDC)4]·5H2O and [Zn2(L2)2(PDC)2]·3H2O based on a couple of tetrahedral linkers (L1 = tetrakis(4-pyridyloxymethylene)methane; L2 = tetrakis(3-pyridyloxymethylene)methane) in the presence of the carboxylate linkers (PDC = pyridine-2,6-dicarboxylic acid). Their structures and properties can be tuned by variable N-donor positions of the tetrahedral isomers. The X-ray crystallographic analysis demonstrate three-dimensional ones of complex 1 and two-dimensional ones of complex 2. This work indicates that isomeric effect of the couple of isomers play an important role in the construction of the Zn(II) complexes. In addition, their thermostability and photoluminescence are also reported in detail.

Highlight► Two coordination polymers have been isolated under hydrothermal conditions. ► Differently oriented N-atoms in the tetrahedral isomers play a significant role in assembly of their final topologies and luminescence-tuning. ► The structural diversity is attributed to both positional isomeric effect of tetrahedral linkers and the steric hindrance of PDC used in the self-assembly process.