Synthesis, Structure, Properties And Theoretical Calculation Of Complexes Constructed By Polyazole-derived Ligands

The functional coordination complexes, which possess the advantages of organic ligands and inorganic metal ions, have potential applications in the field of materials, energy and life sciences. This paper mainly describes the syntheses and crystal structures of a series of transition metal complexes. The optical properties of these synthesized complexes are investigated. Density functional theory（DFT） is used to calculate the hydrogen bonding interaction energies and absorption spectra. This thesis is divided into three chapters:The first chapter is the introduction, which introduces the light-emitting functional complexes, the development of N-containing heterocyclic ligands as well as their complexes, the synthetic methods of the functional coordination complexes, quantum chemistry calculation, the basis of the research and the main achivements in this thesis.In the second chapter, two 5-tetrazolylazo-8-hydroxyquinoline（H2TTHQ） Zn²⁺ and Mn²⁺ complexes of {[Zn（TTHQ）（en）]·2H₂O}（en = ethylenediamine）（1） and {[Mn₂（TTHQ）₂（H₂O）₆]·2H₂O}（2） were synthesized. X-ray diffraction reveals that complex 1 forms a 1-D zigzag chain structure, hydrogen bonds together with π–π stacking interactions link the 1-D chain and lattice water molecules to form a 2D supramolecular structure. Tetrazole ring and hydroxyquinoline ring of TTHQ2– are almost coplanar. Complex 2 is a dinuclear structure, the tetrazole ring and hydroxyquinoline ring of TTHQ2– are nearly perpendicular. The dinuclear structures are connected to 3D supramolecular framework via π-π stacking and hydrogen bonding interactions. The photoluminescent properties for solid samples of H₂ TTHQ and 1 are investigated and a red emission is found. The hydrogen bonding interaction energies are carried out using density functional theory（DFT） with the ωB97XD procedure at 6–31++G（d,p） level.In the third chapter, seven transition metal complexes based on the 1-triazolyl-3-benzimidazolyltriazene（H₃TBIT）, 1-triazolyl-3-benzothiazolyltriazene（H₂TBTT） and 1-tetrazolyl-3-benzothiazolyltriazene（H₂TTBT） ligands of [Co（H₂TBIT）（HTBIT）]（3）, {[Cu（H₂TBIT）（SCN）]·H₂O}（4）, [Cd₂（H₃TBIT）₂（H₂O）2_Cl₄]（5）, {[Ni₃（H₂TBIT）₂（HTBIT）₂（en）₂]·IPA·₂H₂O}（6）, {[Fe（HTBTT）（TBTT）]·H₂O}（7）, {[Fe（HTTBT）（TTBT）]·2TEA·4H₂O}（8）, {[Co（HTTBT）（TTBT）]·TEA}（9）（en = ethylenediamine, IPA = isopropanol, TEA = triethylamine） were synthesized. X-ray diffraction reveals that complex 3 displays a mononuclear structure, hydrogen-bonds link the mononuclear structures into a 2D network paralleling to plane ac, the C-H···π stacking interactions connect the mononuclear structures into another 2D network paralleling to plane bc. complex 4 is a mononuclear structure and the adjacent mononuclear structures are associated through π-π stacking and metal-π interactions, leading to a infinite chains that run along a axis. complex 5 forms dimer which was connected to 3D supramolecular framework via π-π stacking and hydrogen bonding interactions. The 3D supramolecular framework of complex 6 was formed by hydrogen bonds. Mononuclear structures of complex 7 are linked into a 2D network paralleling to plane ab via hydrogen-bonds. Mononuclear structures of complex 8 and 9 are linked into a 1-D chain that run along a axis and b axis via π-π stacking interactions, respectively. Triazene ligands in aqueous solution occur 1,3-prototropic shift and exist in two tautomeric forms（RN=N-NHR′（?）RHN-N=NR′）. Thermal gravimetric（TG） analyses demonstrate that thermal stability improvement after coordination compared with the ligands. The fluorescence properties of triazene ligands H₃TBIT, H₂TBTT andH₂ TTBT together with their transition metal complexes 3-9 are studied at room temperature in ethanol solution and a blue emission is found. The DFT calculations at B₃LYP/6-311++G（d,p） level for H₃TBIT, H₂TBTT and H₂TTBT have been used to demonstrate the characteristic absorption spectra. Calculations of molecular orbital geometry show that the visible absorption maxima of the three triazene ligands correspond to the electron transition from HOMO to LUMO.