Self-Assembly Chemistry Of Ligands Bridged By N-Containing Five-Membered Heterocyclic Rings And Symmetrical Ligands Containing Double Schiff-base

The chemistry of organic-inorganic coordination polymers and supramolecular complexes has recently become an active area of increasing interest internationally. Self-assembly of organic ligands and inorganic metal ions is one of the most efficient and widely used approaches for the construction of organic-inorganic composite materials.In this thesis,a series of bent ligands bridged,respectively,by 1,3, 4-thiadiazole,1,3,4-oxadiazole,4-amino-1,2,4-triazole and 1,2,3-triazole,and bent symmetrical ligands containing double schiff-base units were synthesized.The coordination chemistry based on these new ligands and metal ions was investigated. Totally 11 new coordination compounds were prepared and fully characterized by IR, elemental analysis,X-ray single-crystal diffraction and powdered X-ray diffraction.The luminescent properties,reversible ion-exchange,and thermal stability were investigated.â… .2 dinuclear coordination supramolecules generated from the 1,3,4-thiadiazole bridged ligands and d-block metals Copper(â…¡) and Zinc(â…¡) have been synthesized. Their remarkable ability to distinguish Mercury nitrate from other d-block metal salts by means of fluorescence has been investigated.â…¡.7 discrete closed,semi-closed and polymeric lanthanide-based[Ln(H₂O)₈]³⁺@Ln₂L₄ host-guest systems with tetragonal prism-like structure have been designed and synthesized via ligand-dominated approach by 4-amino-1,2,4-triazole bridged and carboxylic acid terminated ligand.Based on guest-driven approach,the tunable emission and bimodal emission(UV-Vis/NIR) on these[Ln(H₂O)₈]³⁺@Ln₂L₄ supramolecular systems were successfully realized.Moreover,the strong luminescence originated from[Ln(H₂O)₈]³⁺@Ln₂L₄ host-guest system could be quenched by encapsulating of the d-block metal quenchers via solid-state f-d metals exchange.Additionally,the study demonstrated that the photoinduced solid-state guest-independent emission spectrum could be one of the most diagnostic techniques to monitor the solid-state guest-exchange process.â…¢.Coself-assembly of 4-amino-1,2,4-triazole bridged and carboxylic acid terminated ligand and 4,4'-bipy with lanthanide and transition metal ions leaded to a polymer driven by both coordination and hydrogen-bonds.The cause of the decomposition of the 4-amino-1,2,4-triazole ring during the reaction process was discussed.â…£.New types of the 1,2,3-triazole bridged and carboxylic acid or ester terminated ligands were designed and synthesized.Coordination chemistry of these new ligands was investigated,and a coordination polymer was obtained.Besides,the hydrothermal reactivity of ester terminated ligands was explored.â…¤.A series of symmetrical schiff-base ligands were synthesized and their outlook in coordination chemistry was predicted.This study demonstrated that the use of bent ligands bridged by 1,3,4-thiadiazole, 1,3,4-oxadiazole,4-amino-1,2,4-triazole or 1,2,3-triazole and symmetrical ligands containing double schiff-base units as precursors to bind transition metals and lanthanide metals,is in fact an efficient approach for syntheses of novel supramolecular systems with interesting chemical and physical properties.