In situ hydrothermal synthesis of a twofold entangled coordination network based on tetranuclear zinc(II) clusters: An experimental and theoretical study

A new 2D coordination polymer, Zn2(OH)(SDBA)(PTZ) (1), (H2SDBA = 4,4′-dicarboxybiphenyl sulfone, PTZ = 5-(4-pyridyl)tetrazolate) was synthesized via in situ hydrothermal reaction of zinc(II) salt, NaN3, 4-cyanopyridine and H2SDBA, and characterized by elemental analysis, IR, X-ray powder diffraction (XPRD) and single crystal X-ray diffraction. The structure of complex 1 shows a 2D twofold entangled network with (4, 4) topology based on the tetranuclear zinc(II) clusters, which contains unusual both polyrotaxane and polycatenane characters, and further forms a 3D supramolecular architecture by weak π⋯π stacking interactions. Meanwhile, the nature of coordinate bonds in complex 1 has been deeply investigated by high level theoretical calculations. The result of theoretical computation indicates that all coordinate bonds are basically intermediate and covalent dominant interactions in complex 1, and complex 1 has the high thermal stability, which coincides with the result of thermogravimetric analysis (TGA) of complex 1. The photoluminescent property of complex 1 has also been investigated in the solid state at ambient temperature.