Synthesis And Properties Of Metal Complexes From A 1,4,7-triazacyclononane Derivative Bearing Three Propionic Acid Pendant Arms

A unique strategy that employes metalloligands as the building blocks for constructing novel polynuclear clusters or ordered coordination networks can sharply decrease the randomicity of the assembly process.In this regard,the metalloligand approach is certainly one of the most promising ones for the generation of the functional complexes with predesigned architectures and specific functionalities.In this thesis,several potential mononuclear metalloligands with uncoordinated carboxylate oxygen atoms as appended functional groups were obtained by treating tacntpH3(tacntpH3=1,4,7-triazacyclononane-1,4,7-tripropionic acid)with transition metal salts.Fortunately,twenty-one novel complexes based on these metalloligands,which crystallize as hydrogen-bonded supramolecular complexes,metal clusters or low dimensional coordination polymers,were successfully synthesized.Moreover,we discussed the influences of synthetic method,pH value,ratio of ligand to metal as well as size effects of metal ion on the assembly process of these complexes from the perspective of metalloligand.These complexes were characterized by elemental analysis,IR spectra and single crystal X-ray diffraction.Furthermore,nuclease activity and magnetic properties of some of these complexes were preliminary studied.The full text is divided into four chapters:In the first chapter,the research statue of 1,4,7-triazacyclononane derivatives bearing various pendant arms and their metal complexes were summarized.Then,we described briefly the definition and the classification of metalloligands,and also discussed the concrete strategies on the construction of supramolecular complexes from tacn-derived metalloligands.In the second chapter,eleven new metal complexes,namely[Co?(tacntpH2)](ClO4)2·H2O(1)?[Co?(tacntp)]·3H2O(2)?(H3O+){[Co?(tacntp)]2[Co?(H2O)6]}(ClO4)3·7H2O(3)?[Co?5(tacntp)2(H2O)9Cl](ClO4)3·H2O(4)?[Co?9(tacntp)4(H2O)18](ClO4)6·11H2O(5)?[Co?2Ln?(tacntp)2(H2O)3](C1O4)·Cl2·3H2O[Ln=La(6),Ce(7),Pr(8),Er(9)]?[Na2Co?(tacntp)(NO3)]ClO4(10)?[Na4Co?2(tacntp)2(C1O4)(H2O)6](ClO4)3(11)were synthesized.In complexes(1)?(3),[Co?(tacntp)]/[Co(tacntpH2)]2+metalloligands are hydrogen bonded with lattice water molecules or[Co?(H2O)6]2+to yield 2-D supramolecular networks.Complex(4)is a 2-D cluster-based coordination polymer composed of novel cage-like pentanuclear cluster.Complex(5)crystallizes as a nonanuclear species,which exhibits novel double-cage structure.Complexes(6)?(9)reveal similar 2-D heterometallic layered structures.The crystal structures of complexes(10)and(11)consist of 2-D hybrid polymeric layers,where the[Co?(tacntp)]metalloligands are joined by sodium ions into two different metal-organic frameworks.The varied coordination modes of the pendant carboxylate groups in the two complexes are responsible to their structural differences.By analyzing the preparation conditions of these complexes,we found that pH value has important influence on the oxidation state of Co ions.For complexes(1),(2),(3)and(11)prepared by the conventional solution reaction method,pH value of the media,ratio of ligand to metal and the size of the alkali metal ions take effect on the structures of these complexes.As a contrast,only pH value and ratio of ligand to metal play key roles in the construction of complexes(4)?(10)which were synthesized under hydrothermal conditions.Under the physiological conditions,complex(1)does not show the nuclease activity towards supercoiled plasmid DNA.In the third chapter,[Ni?(tacntp)]-was taken as the metalloligand to afford nine new complexes,namely(H3O+)[Ni?(tacntp)]4[Ln?(H2O)8][Ln=Ce(12),Gd(13),Yb(14)],(H3O+)[Ni?(tacntp)2(H2O)12][Ln?(NO3)6]Cl2·3H2O[Ln=La(15),Ce(16),Pr(17)],[Ni?9(tacntp)4(H2O)18](ClO4)6·11 H2O(18),(H3O+)[Ln?Ni?2(tacntp)2](ClO4)2·3H2O[Ln=Er(19),Yb(20)].The crystal structure analysis reveals that complexes(12),(13)and(14)are supramolecular complexes which exhibit rich hydrogen bonding interactions between hydrated rare earth ions and[Ni?(tacntp)]-metalloligands.Complexes(15)?(17)are isomorphous compounds containing the similar pentanuclear cluster units.Complex(18)is a nonanuclear cluster with novel double-cage structure.Complexes(19)?(20)are similar 2-D heterometallic polymers.The variation of the nuclearity and dimensionality of the obtained complexes depends on the following conditions,such as pH value,ratio of ligand to metal as well as the size of the rare-earth metal ions.Antiferromagnetic coupling interactions can be observed between Ni(II)ions in complex(18).In the fourth chapter,a 1-D copper(?)polymer,[Cu?(tacndpH)]ClO4·H2O(21),with tacndp(tacndp=1,4,7-triazacyclononane-1,4-dipropionate anion)as ligand was prepared by Cu(ClO4)2·6H2O and tacntpH3.Interestingly,metal promoted cleavage of one functional pendant arm on the original tri-substituted azamacrocyclic ligand was observed during the complexation.The investigation on the nuclease activity of the complex shows that it cleavages plasmid DNA mainly through oxidative processes.Magnetic studies for the complex show a ferromagnetic exchange along the polymeric chain.