Synthesis, Structure And Characterization Of Metal-salen Based Transition Metal Coordinate Polymers

Recently, metal organic coordination polymers are developing rapidly because of various structures and potential applications. While Schiff-based coordination polymers have also received much attention due to simple preparation, flexible structure, and applications in catalysis, drug delivery, optical, electrical, magnetic materials, etc.Combining the superiorities of both metal-organic and Schiff-based coordination polymers to design new structure has becoming a research hotspot.This paper focuses on the lastest research of metal-organic and Schiff-based coordination polymers and expounds the development of salen-based coordination polymers.In this paper, four new homometallic coordination polymers 1-4 have been prepared by the directly one-step hydrothermal reactions of two carboxylate-functionalized salen ligands(H4L1 and H4L2) with transition metals(M = Zn(II), Co(II) and Mn(II)). Single crystal X-ray diffraction, IR, and TGA have been characterized. 1 exhibits a 3D open framework built by [Zn4(ì4-O)(carboxylate)8] units and double Zn-salen ligands, while 2 shows a 1D chain structure constructed by cobalt ions and the ligand derived from the hydrolysis to one C=N bond of salen ligand. The preliminary fluorescence measurements of 1-2 show the influence of structure on the property. Though 3 and 4 exhibit different 1D chain structures due to different ligands and metal ions, both the 1D chains give 3D supramolecular structures through the intermolecular hydrogen bonds and π···π packing interactions.Magnetic investigation of 4 indicates the presence of antiferromagnetic interactions.