Synthesis Of Saccharide-metal Complexes And The Studies Of Their Catalytic Activities

Although the interactions between the carbohydrates and metal ions have already been observed at the beginning of the past century, similar interactions of sugar type complexes have remained largely unexplored. The major reason for this is that the quantitative characterization of metal ion coordination equilibrium of sugar-type ligands, containing only alcoholic and aldehyde (or ketone) oxygen donor atoms with low electron densities, is difficult to study, which is due to the low stability of the complexes in neutral or acidic aqueous solutions.We have synthesized the stronger binding carbohydrate ligands and complexes by reacting these ligands with metal chloride. They were characterized by elementary analysis, IR, UV spectra analysis and NMR analysis. The polarity of the carbohydrate ligand and complex is very similar, which made it extremely difficult to obtain suitable crystals for X-ray analysis. Fortunately, we got the single crystal of the complexes of [Ni(HL4)] Cl2 2H2O(11) and [Cu(HL2)] Cl2(8). The crystal structures of two complexes have been determined by X-ray diffraction as: complex (11) is distorted octahedron configuration, a - 15.9002(6), b = 16.2413 (5), c = 23.4401(8) A, B= 90, F=6053.2(4) A3, Z=8 and R=0.0531; complex (8) is trigonal bipyramidal configuration, a = 9.3476(8), b = 17.4236 (13 ), c = 9.7836(8) A, B= 91.197(3) , F=1593.1(2) A3, Z=2 and R=0.0325, which shows that three secondary amine groups (N-1, N-2, N-3) of the glycosylamine ligand forms the equatorial plane, and the tertiary amine(N-4) and one Cl- are pointed on the apical positions.We studied the catalytic activities of glycosylamine-metal complexes on hydrolysis of picolinate, phosphate and DNA and found that hydrolysis is significantly accelerated in the presence of complexes over spontaneous hydrolysis. When the complexes were synthesized by the same ligands but the different metalicons, the catalytic activities of Cu(II) complexes were more effectively than that of other metal complexes. In the study of cleavage of DNA, the efficiency of these complexes was much better than that of metal-ethylenediamine complex, which had the similar structure with metal-glycosylamine complexes. The difference between these two kinds of complexes was that one contained saccharide but another not. So we could conclude that the saccharide moiety played an important role in the study of the catalytic cleavage of DNA, and metal-glycosylamine complexes could act as potential DNA cleaving agents.We studied the catalytic activities of N,N'-di-[2-O-( B -D-galacotosyl) benzyl] ethylenediamine-metal complexes on hydrolysis of picolinate, phosphate and DNA and found that hydrolysis is significantly accelerated in the presence of complexes over spontaneous hydrolysis. When the complexes were synthesized by the same ligands but the different metal ions, the catalytic activities of Cu( II) complexes were more effectively than that of other metal complexes.