A cadmium(II) coordination polymer with both polyrotaxane and polycatenane features constructed by a V-shaped semi-rigid ligand: synthesis and fluorescence properties.

Abstract

One of the most interesting phenomena in coordination polymers (CPs) is the co-existence of different interlaced motifs. However, CPs having two different interlaced motifs at the same time are still rare. Colourless block-shaped crystals of the two-dimensional polymer poly[[aqua(μ2-naphthalene-2,6-dicarboxylato){μ2-4,4'-[oxybis(4,1-phenylene)]dipyridine}cadmium(II)] monohydrate], {[Cd(C12H6O4)(C22H16N2O)(H2O)]·H2O}n, (I), was synthesized under hydrothermal conditions by the self-assembly of 4,4'-[oxybis(4,1-phenylene)]dipyridine (OPY) with CdII in the presence of naphthalene-2,6-dicarboxylic acid (H2ndc). Each CdII ion is six-coordinated by two N atoms from the pyridine rings of two OPY ligands and by four O atoms, three of which are from two ndc2- ligands and one of which is from a water molecule. In (I), every two identical two-dimensional (2D) 63 layers are interpenetrated in a parallel fashion, resulting in an interesting 2D→2D framework with both polyrotaxane and polycatenane characteristics. The extension of these sheets into a three-dimensional supramolecular net is via O-H...O hydrogen bonds. The solid-state photoluminescence properties of (I) are also discussed.