In Situ Synthesis, Structure And Fluorescent Properties Of Copper Metal Complexes Based On N-heterocycles Ligands

In situ hydro(solvo)thermal reaction is an environmental, effective and simple method for synthesizing new coordination complexes. The relatively high temperature and pressure may promote unusual in situ new metal-organic ligand reactions, which aren't feasible under traditional conditions. The work of this thesis mainly emphasizes on the studies of in situ synthesis, structure and fluorescent properties of copper metal complexes based on the N-heterocycles ligands. The thesis is divided into four chapters.In the first chapter, the research background is concisely introduced with the emphasis on the current survey of metal organic frameworks (MOFs) and crystal engineering; and the factors in control over the structure of metal-organic frameworks are summarized briefly. The chemistry of in situ generation tetrazole and triazole complexes under hydro(solvo)thermal conditions are also briefly reviewed. In addition, the significance and progress of this work also have been outlined.The second chapter focuses on the systematic investigation of the influence of metal ions and supermolecular interactions on the self-assembly of in situ generated tetrazolate coordination architectures. Three new metal-organic complexes 1, 2 and 3 have been achieved by in situ hydro(solvo)thermal synthesis from the mixture of 2-cyanopyrmidine,sodium azide and copper(I) metal ions. The complexes 1-3 have similar 2D structures. Complex 1 features two dimensional structures based on triazole and tetrazole ligands. Complex 2 contains a six-member ring structure unit, comprised of mildly undulated 2D layers with a (6, 3) topological network. Complex 3 is also two-dimensional with open structure. The results indicate that Cu(I) metal ions and aqueous ammonia play a significant role in the formation of framework and in situ generated tetrazolate and triazole complexes. Furthermore, complex 1 exhibits strong fluorescence and high thermal stability.In chapter 3, four new copper complexes (4, 5, 6 and 7) were obtained under solvo(hydro)thermal conditions, and varied in situ metal-ligand reactions were founded. Complex 4 displays a 0D Cu4I4 cluster, which possesses a chiral space group P21. Complex 5 is a mononuclear structure, and Cu(II) ion adopts an octahedral coordination geometry. There exist four guest water molecules in 5, which form a (H2O)4 cluster. A 3D supermolecular network is formed through the intermolecular hydrogen-bond interactions. The―click‖re ction of tetrazolate in situ formation are found in complexes 6 and 7, both of them displayed 2D structure. Complexes 7 feature porous structure with 1D channel, and the channels are filled with guest molecules. In addition, both 4 and 7 show fluorescent properties.In chapter 4, the studies of in situ―click‖reactions between 4-cyanopyridine and copper (I) salts are carried out. Eight copper(I) coordination polymers (8-15) were obtained by in situ syntheses or transformations; they show guest-depended fluorescent properties. Single X-ray crystal structure studies found that the copper(I)-4-(1H-tetrazol-5-yl)pyridine coordination polymers are synthesized successfully. Complex 8 exhibits 2D grid-like regular sheet with ABAB packing mode, which contains guest water and ethanol molecules. Complex 9 was obtained by removing the guests of 8. Complex 10 was obtained by immersing 9 into another organic solvent. Therefore, the single crystal to single crystal transformation was successfully carried out in 8-10. Complex 11 also displays a 2D grid-like sheet, and the sheets packs with the AAA mode. This different packing mode induced variation of fluorescence in comparative to complex 8 (red shift 60 nm). Surprisingly, the emission of 8 was red shift after grinded the sample; which may be caused by the shorter of the distances between the sheets. When the organic solvents added to the grinded sample, interestingly, the emission of the fluorescence was blue shift immediately. The complexes 12-15 were obtained only by changing the organic solvent in comparison to complex 8. Single crystal X-ray diffractions found that they feature identical 3D structure with varied guest solvent molecules. Complexes 12-15 show varied fluorescent properties, which may be caused by the guest organic molecules. Interestingly, the fluorescence of guest-free complex 12 was quenched after treated with a little nitrobenzene immediately, it indicates that the complex 12 may be the potential material for sensing the nitrobenzene.