Syntheses of Coordination Compounds of 2-Amino-3-Methylbutanoic Acid Their Mixed Ligand Complexes and Antibacterial Activities

Coordination compounds of 2-amino-3-methylbutanoic acid were synthesized with chromium(III) and oxovanadium(IV) ions. M:L;1:2. Adducts of these complexes using 1,10-phenantroline and ethylenediamine were further synthesized, M:L, (1:2). These compounds were characterized using electronic, infra-red spectrophotometry, magnetic susceptibility measurement and percentage metal analyses. The zones of inhibition and minimum inhibitory concentrations of the compounds against eight microbes were studied. The results obtained indicated an octahedral geometry for the Cr(III) complexes, indicative of additional coordination of two water molecules. On the other hand a square pyramid geometry was obtained for the binary oxovanadium complex and its 1,10-phenantroline adduct. However, for the oxovanadium ethylenediamine adduct a distorted octahedral geometry was proposed. The result for the antibacterial studies indicated that both mixed ligand complexes of 1,10-phenantroline exhibited good antibacterial activity, and in some cases better activity than the standard, streptomycin.

Syntheses, Characterization and Biological Activity of Coordination Compounds of 3-Hydroxy-2-methyl-4<i>H</i>-pyran-4-one and Its Mixed Ligand Complexes with 1,2-Diaminocyclohexane

Coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one with iron(III), cobat(III) and chromium(III) were synthesized with M:L (1:2). Mixed ligand coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one and 1,2-diaminocyclohexane using the same metal ions were also synthesized M:L1:L2 (1:1:1) where L1 is 3-hydroxy-2-methyl-4H-pyran-4-one and L2 is 1,2-diaminocyclohexane. The coordination compounds obtained were characterized using electronic and infrared spectral analyses, magnetic susceptibility and percentage metal analysis. They were also evaluated for their cytotoxic and antioxidant activities. The result obtained suggested that octahedral geometry was obtained for all the compounds, as a result of additional two molecules of the solvent coordinated to the metal ions. Both the primary and secondary ligands coordinated in a bidentate fashion. The synthesized compounds exhibited moderate cytotoxicity, although none was as active as the standard. The cobalt(III) mixed ligand complex elicited the highest activity. The synthesized compounds all exhibited good to moderate antioxidant activity.

The synthesis and structural studies of mixed ligand complex,tris(1-phenyl-3-methyl-4-trifluoroacetylpyrazol-5-one)mono(1-phenyl-3-methyl-pyrazol5-one)neodymium(Ⅲ)monohydrate

A mixed ligand neodymium complex containing 1-phenyl-3-methyl-4-trifluoroacetyl- pyrazol-5-one(HPMTFP)and 1-phenyl-3-methyl-pyrazol-5-one(PMP),with molecular formula Nd(PMTFP)_3·PMP·H_2O was synthesized.Its crystal and molecular structure has been determined by single crystal X-ray diffraction method.The complex crystallizes in monoclinic system with space group C_2~5h-P2_(1/n).There are four formula units in a cell of dimensions a=12.837(3),b=23.763(5),c=16.810(4) ,β=109.58(2)°.The structure has been refined by full-matrix least-squares techniques to a final R value of 0.0487 and Rw value of 0.432.The neodymium atom is coordinated to eight oxygen atoms with the average Nd-O bond length 2.439,Its thermostability,and mass spectrum have been discussed.

Thermodynamical study on the formation of some mixed ligand complexes of non-transition metal ions in solution——Ⅰ. The formation and the stability of some Pb(Ⅱ) mixed ligand complexes

The stability constants of the binary complexes of type PbB, PbB_2, and the mixed ligand complexes of type PbAB have been studied by potentiometric pH titration technique at ionic strength I=0.10 (KNO_3) and at temperature 15, 25, 35 and 45℃ respectively, where A=2,2'-bipyridyl (bipy) or 1, 10-phenanthroline (phen); B=malonate (mal), succinate (suc), or anthranilate (anth). The equalibrium constants logK,~1 G, H, and S of the reaction PbA+PbB=PbAB+Pb^2+ have been calculated. The results show that the discriminating effects^2 between the primary ligand (bipy or phen) and the secondary ligand (real, suc or anth) in those non-transition metal mixed ligand complexes are also evident, and as a measurement of this effect, H is more appropriate than logK. The possible reasons which lead to these results have been discussed.