Two birds with one stone: Self-assembly of metal–organic coordination complexes with discrete metallamacrocycle and 1D zigzag chain based on a flexible dicarboxylate ligand

To assemble metal–organic coordination complexes, a flexible dicarboxylate ligand, 2,2′-(4,6-dimethyl-5-nitro-1,3-phenylene)bis(methylene)-bis-(sulfanediyl)dibenzoic acid (H2L), has been designed and synthesized. Using the flexible ligand to assemble with copper ions, a mixture of two metal–organic complexes, Cu2(L)2(py)4·4dmso (1) and Cu2(L)2(py)6·3dmso·py (2), has been generated by solvothermal technology in one glass tube. Through increasing the mole fraction of pyridine, the pure phase of complex 2 was obtained. Both complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle. The guest solvents of dimethyl sulfoxide molecules were trapped in the cavity of rectangular metallmacrocycle, resulting in the formation of an infinite supramolecular metal–organic nanotube through van der Waals interactions between the guests and the host molecules. In complex 2, the flexible ligand adopts a syn conformation to assemble with copper ions to form an infinite one-dimensional zigzag chain.

The structures of the two complexes vary from discrete metallamacrocycle to 1D zigzag chain with the flexible ligands that are in the syn conformation and the two complexes were gotten in the same glass tube. Because of the existence of the guest molecular, the metal-organic supramolecular nanotubes were formed.Figure optionsDownload as PowerPoint slideHighlights
► Two new copper(II) coordination complexes based on a flexible dicarboxylate ligand were synthesized and characterized.
► The flexible ligands in the syn conformation assembled with Cu (II) generated discrete macrometallocycles and 1D zigzag chain subunits in the same glass tube.
► And through increased the mole fraction of pyridine, the pure phase of complex 2 was obtained.
► The metal-organic supramolecular nanotubes were formed because of the existence of the guest molecular.