Self-assembly of metal-organic supramolecules: From a metallamacrocycle and a metal-organic coordination cage to 1D or 2D coordination polymers based on flexible dicarboxylate ligands

摘要

To assemble metal-organic supramolecules such as a metallamacrcocycle and metal-organic coordination cage (MOCC), a series of flexible dicarboxylate ligands with the appropriate angle, 2,2′-(2,3,5,6-tetramethyl-1,4- phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H_2L ~1), 2,2′-(2,5-dimethyl-1,4-phenylene)bis(methylene) bis(sulfanediyl)dibenzoic acid (H_2L~2), 2,2′-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl) dinicotinic acid (H_2L~3), and 2,2′-(2,4,6-trimethyl- 1,3-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H_2L ~4), have been designed and synthesized. Using these flexible ligands to assemble with metal ions, six metal-organic supramolecules, Cd _2(L~1)_2(dmf)_4(H_2O) _2·H_2O (1), Mn_3(~1L ~2)_2(~2L~2)(dmf)_2(H _2O)_2·5dmf (2), Cu_4(L~3) _4(H_2O)_4·3dmf (3), Cu_4(L ~4)_4(dmf)_2(EtOH)_2·8dmf· 6H_2O (4), Mn_4(L~4)_4(dmf) _4(H_2O)_4·6dmf·H_2O (5), and Mn_3(L~4)_3(dmf) _4·2dmf·3H_2O (6), possessing a rectangular macrocycle, MOCCs or their extensions, and 1D or 2D coordination polymers, have been isolated. All complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle, while complex 2 is a 2D macrocycle-based coordination polymer in which the L~2 ligand adopts both syn and anti conformations. Complexes 3-5 are discrete MOCCs in which two binuclear metal clusters are engaged by four organic ligands. The different geometries of the secondary building units (SBUs) and the axial coordinated solvates on the SBUs result in their different symmetries. Complex 6 is a 1D coordination polymer, extended from a MOCC made up of two metal ions and three L~4 ligands. All of the flexible dicarboxylate ligands adopt a syn conformation except that in complex 2, indicating that the syn conformational ligand is helpful for the formation of a metallamacrocycle and a MOCC. The magnetic properties of complexes 5 and 6 have also been studied.