Synthesis And Properties Of Nitrogen-containing Aromatic Ligands

In this dissertation monodeprotonated 2,2'-bypyridine-3,3'-diol have been selected as ligand and ten novel complexes have been designed and synthesized, namely, [Cu₂(μ2-OOCCH₃)₂(HL)₂(H₂O)₂](1) (HL=bpydiol-H = monodeprotonated 2,2'-bypyridine-3,3'-diol),[Ni(HL)₂]_n (2),[Cu(μ-HL)(NCS)]n (3),[Cu(μ-HL)(H₂O)₂(NO₃)]_n (4), [Cu₂(μ-HL)₂(OOCH)₂(H₂O)₄]₂H₂O (5),[Cr(HL)(OH)] (6),[Cd(μ-HL)(μ-N₃)(HOCH₂CH₃)]_n (7), [Zn₂(μ-HL)₂(HL)₂(H₂O)₂] (8), [Co(HL)₃]1.5H₂O (9) and[Zn(HL)₂(H₂O)] (10).The ten novel complexes were characterized by element analysis and IR spectra, and their crystal structures were determined by X-ray crystallography. The variable-temperature magnetic susceptibilities of complexes (1), (2), (3), (4), (5) and (6) were measured. For the binuclear complex (1), there isπ?πstacking interaction between adjacent pyridyl rings. The theoretical calculations reveal that acetate bridge ligand led to an anti-ferromagnetic coupling with 2J = ?166.72 cm?1, whereasπ?πstacking developed a ferromagnetic interaction with 2J = 21.0 cm?1. The offset from the anti-ferromagnetic interaction and the ferromagnetic interaction may be one of main factors that resulted in the weaker magnetic coupling with experimental fitting 2J = ?59.61 cm?1.For the one-dimensional chain Cu(II) complex (3), The variable-temperature (2-300 K) magnetic measurements were analyzed using a one-dimensional Cu(II) magnetic interaction formula and it indicate the existence of very weak anti-ferromagnetic coupling with 2J = ?11.56 cm?1. For the one-dimensional chain Cu(II) complexes(4), The fitting for the data of the experimental variable-temperature (2?300 K) magnetic susceptibilities reveals that there exists a very weak ferromagnetic coupling between the bridged Cu(II) ions with 2J = 0.014 cm?1. The complex (3) exhibits a weak anti-ferromagnetic interaction, whereas the similar one-dimensional complex (4) displays a very weak ferromagnetic interaction. The different coupling characters reveals that monodeprotonated 2,2'-bypyridine-3,3'-diol belongs to a kind of bridge ligands that only lead to the weak magnetic coupling.The magnetic behaviors of both the complex (2), (5) and (6) were analyzed with their structural factors. The spin-canting property was observed at low temperature for a one-dimensional chain Ni(II) coordination complex (2). For complex (5) the fitting based on binuclear Cu(II) formula indicates that there exists a weak ferromagnetic exchange interaction between the bridged Cu(II) ions with 2J =15.37 cm?1. For the mono-nuclear complex (6), Cr(III) ion assumes a distorted five-coordinated CrN4O1 bi-trigonal-pyramidal geometry and there is an anti-ferromagnetic coupling between the complexes duo toπ?πstacking interaction.The fluorescent spectra were measured for complexes (7) and (8), and the study dealing with the structures and fluorescent properties has been made, in which complex (7) and (8) exhibit the similar fluorescent properties duo to their similar structures.The special advantages and contributions of this dissertation are as follows:1. A series of novel complexes with monodeprotonated 2,2'-bypyridine-3,3'-diol as ligand have been synthesized, which has not been reported as yet. The dissertation will benefit design and synthesis of the novel complexes with the derivatives of bipyridine as ligands.2. The magnetic coupling mechanisms were studied for the three one-dimensional chain coordination polymers (2), (3) and (4), and the two binuclear Cu(II) complexes (1) and (5). The spin-canting property was observed for a one-dimensional chain Ni(II) coordination complex.Theoretical calculations hav been made to evaluate magnetic coupling intensity forπ?πstacking system of the two binuclear Cu(II) complexes (1). It is the first example to evaluate magnetic coupling intensity for non-radicalπ?πstacking system with theoretical calculations. The dissertation will benefit the study of magnetic coupling intensity for non-radicalπ?πstacking system.The results of this dissertation will benefit the synthesis of ideal molecular-magnets and it also benefits the understanding for bio-function of bridged metallic ions in metallic proteins. The results of this dissertation also will benefit the synthesis of ideal fluorescent materials.