Assembly of three novel metal (II) complexes based on polycarboxylate and 1,10-phenanthroline ligands

With the principles of crystal engineering, three novel metal(II) complexes, [Cu2(betd)(phen)4].15H2O (1), [Cd4(betd)2(phen)8]⋅28H2O (2) and {[Co2(betd)(phen)2(H2O)2]·2H2O}n (3) (H4betd = bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid, phen = 1,10-phenanthroline) were synthesized and structurally characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses, TGA, powder XRD and fluorescent measurements. Complex 1 is a binuclear structure, novel water tapes are observed to be encapsulated in the 3D open supramolecular architecture by hydrogen bond interactions. In 2, two pairs of CdII ions joined with two (betd)4− ions to form a cyclic tetranuclear structure. The neighboring tetranuclear units are linked into 2D network through π⋯π stacking interactions. Interestingly, the lattice H2O molecules are joined by strong hydrogen bond interactions generating a wavy water layer, which contacts the 2D network to form 3D supramolecular structure. 3 shows a 2D (4, 4) grid network, which are assembled in an ABAB sequence to 3D supramolecular structures via π⋯π stacking interactions between two central phen ligands from two adjacent sheets and hydrogen bond interactions.

Graphical abstractTo determine the influence of metal ions on the formation of complex, three complexes were synthesized and characterized. Hydrogen bonding and π⋯π stacking interactions link them to form 3D supramolecular architectures. Especially, 2 contains a novel water molecule network formed by condensation of fused (H2O)14 clusters. The thermal stabilities and luminescence properties were also studied.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Three metal (II) complexes with polycarboxylate and 1,10-phenanthroline ligands. ► The synthesis shows that metal center plays the key role. ► 1 and 2 contain the novel water tape and layer formed by water clusters.