Polythreading of Infinite 1D Chains into Different Structural Motifs: Two Poly(pseudo-rotaxane) Architectures Constructed by Concomitant Coordinative and Hydrogen Bonds

Two new compounds, [Co(4,4‘-bipy)(H2O)4]·(H2bptc)·2H2O (1) and [Ni(4,4‘-bipy)(H2O)4]·0.5(btc)·H2O (2) (4,4‘-bipy = 4,4‘-bipyridine, H4bptc = 3,3‘,4,4‘-biphenyltetracarboxylate acid, H4btc = 1,2,4,5-benzenetetracarboxylate acid), have been
synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction.
X-ray structural analysis revealed that two different structural motifs (1D covalent zigzag chain and 1D hydrogen-bonded ladder for
1 and 1D linear chain and 2D hydrogen-bonded sheet for 2) can be found within their crystal structures, and most intriguingly, they
coexist in such a way that 1D covalently bonded chains of composition [M(4,4‘-bipy)(H2O)4]2+ (M = Co or Ni) thread into the
hydrogen-bonded 1D ladders or 2D sheets formed by uncoordinated carboxylate anions and lattice water molecules, giving rise to
overall entangled architectures with unusual poly(pseudo-rotaxane)-type arrangements. Thermal stability of the two compounds was
also studied in this paper.