Syntheses, Characterization, Structure And Properties Of Complexes With Terpyridine And Terpyridine-like Ligands

One of the most important used in modern coordination chemistry is the aspect of N-heteroaromatic ligands, which largely based on pyridine, 2,2'-bipyridine, melamine, and 2,2':6',2"-terpyridine (simply terpyridine), have become an ever-expanding synthetic, application and structural frontier. Terpyridine ligands and the tailored terpyridine derivatives (especially 4'- functionalized terpyridines) are stronge tridentate ligands and have much advances and ever-expanding potential applications. Their well-known characteristics are applied in the fields of optical, catalytic, molecular recognition, gas storage, solar cell and so on. Also they could self-assemble lots of intriguing topological structures.Firstly, this thesis focuses on the synthesis of three 4'- functionalized terpyridine with 4-hydroxyphenyl,2-furyl and carboxylic acid. Several coordination compounds have been prepared by the reaction of d¹⁰ metals (Cd²⁺,Zn²⁺) with these ligands. All compounds are characterized by elemental analysis, IR, emission spectra and single-crystal X-ray diffraction.On the other hand, we think melamine and 2,6-bis(2-furyl)pyridine are very useful terpyridine-like ligands. Three novel melamine complexes with copper(II) including sandwich and extensive hydrogen bonds were obtained. Moreover, a new ligand of 4-(4'-Hydroxyphenyl)-2,6-bis(2-furyl)pyridine has been synthesized and may be uesd as pH sensor.In detail, the work is divided into six chapters as following:In Chapter 1, the research background of the synthesis of 4'-functionallized terpyridine and the current survey of terpyridine coordination compounds in particular optical properties and supermolecular assemblies are concisely introduced. A survey of melamine and 2,6-bis(2-furyl)pyridine are also mentioned.In Chapter 2, the cadmium(II) complex, Cd(p-HO-ptpy)Cl₂, p-HO-ptpy being a tridentate ligand 4'-(4-hydroxyphenyl)-2,2':6',2"-terpyridine has been synthesized and the crystal structure is determined using X-ray crystallography. Furthermore, its luminescent and electrochemical properties compared with the ligand have been investigated.In Chapter 3, the cadmium(II) complex, [Cd(ftpy)I₂]·CHCl₃, which ftpy being a ligand of 4'-(2-furyl)-2,2':6',2"-terpyridine has been synthesized. Furthermore, its crystal structure and luminescent properties compared with the ligand have been investigated.In Chapter 4, five mononuclear complexes c1-c5 and a mononuclear polymer c6 containing the ligand of 2,2':6',2"-terpyridine-4'-carboxylic acid (Hctpy) were prepared by hydrothermal method. The metallic ions in c1-c5 have distorted octahedral coordinations with six nitrogens from two molecules of Hctpy. But 1D chain structure of complex c6 is built by carboxylic acid of Hctpy and resulted in the enhanced emission band. The coordination mode of c6 has never been reported.In Chapter 5, a new ligand of 4-(4-Hydroxyphenyl)-2,6-bis(2-furyl)pyridine had been synthesized by two methods. Furthermore, this compound exhibits novel ultraviolet and electrochemical properties under the influence of pH value. The reason and the mechanism of Hpfpy may be tentatively assigned.In Chapter 6, three copper(II) coordination compounds have been synthesized and researched by cyclic voltammograms. Two novel melamine coordination compounds of them including the copper directly bonded to the aromatic rings of melamine have extensive hydrogen bonds and consolidate a 2-D sheets. Interestingly, one is a dinucear complex with a paddle wheel structure in which the apical positions are occupied specially by two different donor ligands.