Study On Novel Functional Diazamesocyclic Ligands And Their Complexes

1, 5-Diazacyclooctane (DACO), a typical diazamesocyclic ligand, is the smallest member of the cyclic polyamines family. Although its synthesis was reported several decade ago, research on this field is extremely limited, compared with the thorough research on saturated macrocyclic tri- and tetraamines. diazamesocyclic ligand, as an important system between the macrocyclic ligand and the open-chain ligand, has special spatial structure and obtains extremely strong ligand field effect. DACO also acts as the most typical diazamesocyclic ligand. With it's highly symmetrical structure, the unique conformation (usually takes an interesting"boat/chair"configuration in transition metal coordination complexes), it can be changed into the form of specific tetra- or penta-coordinate configuration, while complexing with metallic ion. DACO itself only has two coordinate nitrogen atoms; therefore its coordination chemistry research is extremely limited. Firstly, its own structure characteristic and the nature of coordination chemistry and some else most basic questions have not been solved and explained, such as the preparation conformation and the spatial arrangement of the uncoordinated DACO and the influence of the center metallic ion coordinate configuration. Secondly, compared with the macro cyclic polyamines, the DACO derivative coordination chemistry obviously has not been given a systemic thorough research. Through making the reasonable designs and doing some decorations to the framework of DACO, such as by adding the attachment of donor pendants, can strengthen its coordinate ability with metallic ion. Also because DACO only includes two nitrogen atoms, its functional derivative's preparation and the structure are relatively easy to control. If other metallic ion complexes with it, it could be found to be formed penta-coordinate configuration. These factors enable us to have the possibility of adjusting the structure and the performance of the final preparation through reasonable designs.This article, on one hand, preparation and characterization two new bi-heterocyclic (imidazole) functionalized DACO derivatives and a mono- phenol substituted DACO and their complexes with Cu (II), Ni (II), Co (II) and Zn (II). The crystal structures of these complexes show that doubly sub-stituted tetra dentate heterocyclic ligands normally tend to form stable penta-coordinated [MLCl]+ type mononuclear complexes, due to the boat-chair configuration of DACO, and the coordination geometries of the metal centers are changed according to their different steric bulk, which could serve as...