Syntheses, Structures And Performances Of Transition-metal Supramolecular Compounds Constructed By Carboxylate Or Sulfonate

Study on the coordination complexes constructed by transition metals and ligands containing muti-functional groups is an active research field in recent years. Coordination complexes exemplify how crystal engineering has become a paradigm for the design of new supramolecular structures. Due to the wide applications of coordination complexes in photo-electricity, adsorption, magnetic materials etc., much attention has been devoted to the design and syntheses of novel kinds of structural topologies and compounds with special properties. It is important to master the factors influencing the structure of the coordination complex, such as solvent, pH and temperature etc., so that we can control the formation of the complexes. In the past several decades, carboxylate ligands have been widely studied because of strong coordination ability and varieties of coordination modes; however, studies on sulfonate ligands have been only attracted attention in recent years. In this thesis, we try to synthesize novel supramolecular complexes by the use of carboxylate or sulfonate ligands assembling with metal ions through coordinative bonds or supramolecular weak interactions and to study the factors influencing the final structures and properties. The assembly reactions of rigid benzene-muti-carboxylate with metal ions have yielded 17 coordination complexes. This thesis is divided into seven chapters.1. In the first chapter, the concepts, and histories of supramolecular chemistry are concisely introduced, as well as the current survey, research significance and the results in this thesis.2. In the second chapter, after the synthetic methods of supramolecular complexes are summarized by and large, the concepts and methods of hydrothermal reaction are concisely introduced, as well as its application fields.3. In the third chapter, three new one-dimensional zigzag chain coordination polymers based on isophthalate as bridging ligands and imidazole as non-chelating capping ligand, {[Cu(ip)(Him)₂(H₂O)]·3H₂O} (1),{Cu(ip)(Him)₂(DMF)·H₂O} (2) and {Co(ip)(Him)₂} (3), have been in detail described. All of them display 3-D interestingly supramolecular networks, however, their supramolecular networks are significantly different due to the difference in coordination environment of metal centers (copper in 1 and 2 being square pyramid and cobalt in 3 being in tetrahedron, respectively) and different noncovalent contacts. In the formation of 3D supramolecular networks in complex 1-3, the imidazole ligand plays an important role for it provides not only a unique and efficient hydrogen bonding synthon but also supramolecular recognition sites forπ–πand C-H···πmolecular contacts. There exist antiferromagnetic interactions between magnetic centers in compound 1 and 3.4. In the fourth chapter, constructions and structures of four copper coordination polymers are described, [Cu₃(ipO)₂(H₂O)₂]n (4), [CuIICuI(ipO)(4,4′-bpy)] (5) [Cu₃(ipO)(4,4′-bipy)(H₂O)₂] (6) and [CuIICuI(ip)(ipH)(4,4'-bipy)_3/2] (7). In compounds 4-6, in situ hydroxylation of isophthalate into 2-hydroxyisophthalate is involved, however, no in compound 7. Compounds 4-7 were all obtained through redox reactions of copper ions under hydrothermal condition. The results show that: (1) we have found that isophthalate can be oxided by oxygen while catalysed by Cu-,and the oxidation of isophthalate is correlated with the pH value of the reaction system. (2) Compound 6 is the first mixed penta- and hepta-coordinate copper coordination compound.5. In the fifth chapter, two new coordination complexes based on bta and imidazole ligand, [Ni₂(Him)12·(bta)·8H₂O] 8 and [Cd₂(Him)4(bta)] 9, have been described. Compound 8, consisting of two crystallographically independent [Ni(Him)6]2+ fragments, an uncoordinated bta4- anion and eight lattice water molecules, displays an interesting 3-D supramolecular network constructed by cationic layers (layer A) and anionic layers (layer B) with ABAB sequence through hydrogen bonding interactions. In complex 9, each bta ligand links four metal ions to form a one dimensional (1D) double chain. The 1D double metal chains are assembled into a 3D supramolecular network through N-H···O hydrogen bonding and C-H···πinteractions. Complex 9 shows strong blue fluorescence at room temperature.6. In the sixth chapter, eight complexes constructed with 5-sulfosalicylic acid and bipyridyl-like ligands (2, 2′-bipy and 1,10-phen) were described, namely, [Cu4(OH)₂(ssal)₂(phen)4·7H₂O] 10, [Cu4(OH)₂(ssal)₂(bipy)4·2H₂O] 11, [Cd(Hssal)(bipy)] 12, [Cd(HL)₂(phen)₂] 13, [Cr(ssal)(bipy)(H₂O)₂·2H₂O] 14, and [Cr(ssal)(phen)₂] 15, Mn(Hssal)(bipy)₂(H₂O)·2H₂O 16,Zn(Hssal)(bipy)(H₂O)₂ 17 (H3ssal = 5-sulfosalicylic acid, H₂L = p-hydroxybenzenesulfonic acid, bipy = 2, 2′-bipy, phen = 1,10-phen). Complexes 10 and 11 are both constructed by tetra-nuclear copper cluster. In complex 12, a new coordination mode of Hssal2- group was found. During the synthetic process of complex 13, in situ decarboxylation of 5-sulfosalicylic acid into p-hydroxybenzenesulfonic acid is involved. Two chromium 5-sulfosalicylates (14 and 15) are both firstly synthesized. The mononuclear complex 16 displays an interesting 2D supramolecular double-layer through hydrogen bonding andÏ€-Ï€interactions. Compound 17 displays 1D helical chain, which is connected into an interesting 2D supramolecular double-layer through hydrogen bonding andÏ€-Ï€interactions. The results of magnetic determination show there exist ferromagnetic interactions in complex 10, however, antiferromagnetic interactions in 11.7. In the seven chapter, a brief concusion and outlook of this thesis are given.