Synthesis,Crystal Structure And Properties Of Complexes With Schiff Bases Derived From Benzaldehyde

Schiff bases compounds have attracted a lot of attentions for a long time, because of their application in catalysis, simulating enzyme, antibody, and molecular identification and so on. Of these, the earliest and most research was on the Salicylideneamine. Salicylideneamine stands for a sort of N, O-donating ligands deriving from condensation of salicylaldehyde and amines, which with easy preparation, good physical stability and with very high activity and various coordination manners with metal ions, over the years it has been the focus of the study. Salicylideneamine and their complex were used in catalytic and biological models, and their properties of luminousness, photoluminescence, absorbing, magnetism and anti- magnetism will make them have the potential significance in the developments and applications of new materials.On the basis of early experiments, two bis-Schiff bases were selected and reducted by NaBH4, and two new nitrogenous compounds were obtained. In addition, five crystals of complexes with the salicylideneamine have been obtained, and the fluorescent properties have also been studied. The contents of this work contain five parts:(1) Recent development, application and prospect for Schiff base complexes were reviewed, and the reduction of Schiff base were also discussed.(2) In this paper, sodium borohydride were used as a reducing agent, and two bis-Schiff base:N1-(4-hydroxy-3-methoxylbenzylidene)-N2-(2-(4-hydroxy-3-methoxybenzylidene)ethyl)-1,2-ethylenediamine (Schiff base 1)and N1-(4-hydroxylbenzylidene)-N2- (2-(4-hydroxylbenzylidene)ethyl)-1,2-ethylenediamine(Schiff base 2), were selected and reducted by NaBH4. After reduction, two new nitrogenous compounds were obtained: N1-(4-hydroxy-3-methoxylbenzyl)-N~2-(2-(4-hydroxy-3-methoxylbenzyl)ethyl)-1,2-ethylene ammonium salt (L1·3HCl)and the N~1-(4-hydroxylbenzyl)-N~2-(2-(4-hydroxylbenzyl) ethyl)-1,2-ethylene ammonium salt (L2·3HCl). They were characterized by elemental analysis, IR spectra, 1H NMR, MS and UV-vis. The protonation constants of reductive products and the stability constants their complexes with Cu(Ⅱ) were determined, the equilibrium constants were determined with the program BEST, the species distribution diagrams were obtained with the programs Repro40 and Repro.(3) The Ni(Ⅱ), Cu(Ⅱ) complexes of N,N'-bis-(2-hydroxyl-benzyl)- triethylenetetramine, which were characterized by elemental analysis, X-ray single crystal diffraction analysis, the accurate structure of the complex were determined and the property of them were inferred preliminarily.(4) A bis-Schiff base ligand was obtained by the condensation of salicylaldehyde and triethylenetetramine of a 3:1 ratio, three dinuclear complexes with transition metal (Ni, Cu, Zn) of this ligand were synthesized, they were characterized by elemental analysis, IR spectra, 1H NMR, and X-ray single crystal diffraction analysis, while their fluorescent property were determined at room temperature, results showed that: copper and nickel complexes have no fluorescence, while the zinc complex have stronger fluorescence, thus increasing its possibility of application in fluorescent materials. By DFT calculation, the fluorescent property of the ligand and its zinc complex were further understood and the reasons for the change of the fluorescent intensity were explained.(5) At last, the summary for the contents of this paper was discussed, and the prospect for Schiff base complexes and the development of our work were reviewed.