Chemistry

The reaction of the Schiff base species tris-((2-hydroxybenzylidene)aminoethyl)-amine (TrenSal) and tris-((2-hydroxy-5-bromobenzylidene)aminoethyl)amine (Tren5BrSal) with the acetates of nickel and zinc are reported. Two trimetallic complexes (M3L2) of Tren5BrSal with nickel and zinc have been crystallographically characterised. The attempted crystallisation of bis-(tris-((2-hydroxybenzylidene)aminoethyl)amine nickel) nickel from solutions containing TMEDA lead to the production of two novel complexes: namely a nickel adduct of the partially hydrolysed TrenSal ligand and an interesting nickel bromide–carbonate salt. [(TrenSal)2Ni3] is reacted with PbCl2 to form a novel tetrametallic complex, [{(TrenSal)Ni}Pb(NC5H5)Cl]2, where a Pb2Cl2 moiety replaces the nickel at the core of the complex. Extending the study to include the related hexadentate ligand, 1,1,1-tris-((2-hydroxybenzylidene)-aminomethyl)propane (TEtSal), we were able to isolate and characterise both [(TEtSal)2Ni3] and [{(TEtSal)Ni}2Pb].A number of multi-metallic Schiff base complexes (M3L2, M = Ni, Zn; Ni2PbL2 and Ni2Pb2L2) have been synthesised and crystallographically characterised. The attempted crystallisation of Ni3L2 leads to the production of two novel complexes: namely a partially hydrolysed Schiff base complex and an interesting nickel bromide–carbonate salt.

The nickel and zinc complexes of 2-aminomethylaniline (AMA) are reported. Both metals form the octahedral complex [M (AMA) 2 (ONO2) 2](M= Ni, Zn) where the aromatic ligands lie in the meridial plane with the anilino donors trans to one another. The remaining ...

ABSTRACT The multidentate compound, tris-(o-tbutylthiobenzyl)-aminoethylamine (L4), which contains four nitrogen and three sulfur donors has been synthesised by combining 2-amino-methyl-1,3-diamino-propane (tren) with o-tbutylthiobenzaldehyde. L4 has been reacted with the nitrate salts of nickel, copper and zinc to give a series of L4M(NO3) complexes which were crystallographically characterised. In all cases the metal binds to the N4 motif proffered by the tren moiety. The nickel complex achieves a hexacoordinate geometry by ligating with a didentate (–O,O′) nitrate. Copper and zinc both produced five coordinate species by ligating with a unidentate nitrate. None of the species reported include the thio-ethers in the coordination sphere of the metal. Replacing nitrate with nitrite in the copper system allows the synthesis of a five coordinate unidentate, oxygen bound, nitrite complex. A number of unsuccessful attempts have been made, using Cd, Pb and Au, to assemble the three thioethers groups into a secondary coordination motif for metals. These reactions produce a series of L4M–halide complexes which have again been crystallographically characterised.

Three Cu(II) co-ordination compounds with a novel ligand, 5-formyluracil thiosemicarbazone (H3ut), have been synthesised and characterised by single-crystal X-ray diffraction and subsequently tested in vitro on human leukemic cells. The crystal structures revealed, in all three cases, a square pyramidal co-ordination geometry of the copper atom with the ligand lying on the basal plane and behaving as an SNO terdentate ligand. These three compounds have been tested on human leukemic cell line K562 and CEM. In these experiments the complexes have demonstrated to inhibit cell growth and one of them to induce apoptosis. In the paper we also report the spectrophotometric characterization of the free ligand.

The synthetic utility of tris-((2-hydroxybenzyl)-aminoethyl) amine (H6TrenSal) and tris-((2-hydroxy-5-bromobenzyl)-aminoethyl) amine (H6Tren5BrSal) are investigated. A range of monomeric complexes with general formula [(H6TrenSal) M][NO3] with nickel, copper and ...

... Children are especially prone to acci-dental poisoning of this product (Okeniyi and Lawal, 2007). ... Variations were considered significant at p < 0.05. Page 3. Musa et al. 051 Figure 2. Frequency distribution of dichlorvos concentrations %w/v in Ota-piapia samples. ...

Tris-2-aminoethylamine was condensed with 5-bromosalicylaldehyde to yield the potentially heptadentate N4O3 ligand, the ligand synthesis was followed by complexation with metal ions (M= Fe 2+ , Mn 2+ ). The complexes were characterized by infrared and UV visible, while their melting point, solubility and conductivity were investigated. The ligand C=N band appear at 1645 cm -1 while the C=N band infrared absorption vibration appears at 1622 cm -1 and 1626 cm -1 for iron and manganese complexes respectively. The UV absorption bands appear at low wavelengths, that is 420nm for manganese and 480nm for iron complex. Anti microbial screening on the complexes revealed that the monometallic complexes were active in inhibiting microbial growth. Keywords : Iron, Manganese, Multidentate, Schiff base

A series of four mixed ligand complexes were synthesized by reacting benzoylacetone and salicylaldehyde with different metal chlorides in ethanolic medium. The complexes have been characterized by molar conductance measurements and spectral techniques such as IR and Uv-visible electronic spectra. Decomposition temperature was also determined. The results indicated that the compounds have bands at 400-500cm, with very sharp melting points. This proved the formation of metal-oxygen bond, purity and high thermal stability of the compounds that could lead to a high antimicrobial activity.

Synthesis of acetylacetonato, ethylenediamine manganese (II) complex and acetylacetonato, ethylenediamine iron (II) complex were carried out, a pale yellow and brown solids were obtained from the reaction.  The solubility tests of the complexes were carried out, in which manganese (II) complex was found to be soluble in water, methanol and ethanol and insoluble in chloroform and petroleum ether while the iron (II) complex was found to be slightly soluble in water, methanol and ethanol and insoluble in chloroform and petroleum ether. The UV visible spectra of manganese (II) complex showed absorption maximum at around 480nm, and infrared spectra of manganese (II) complex showed absorption band at 1725cm -1 . Keywords: Acetylacetone, manganese, iron, ethylenediamine.

The Schiff base ligand (N’,E,N”E)-N’,N”-bis(1-pyridin-2-yl)ethylidene)cyclohexane-1,2-diamine and its Zinc complex was synthesized and characterized by CHN, FTIR, 1 H-NMR and UV-visible analysis whereby the structure of the Schiff base was confirmed by X-ray diffraction analysis, showing that the cyclohexane ring adopts a chair conformation with the two imine groups linked at equatorial positions. The two halves of the molecule are related by a crystallographic two fold rotation axis. The dihedral angle between the pyridine rings is 75.73 (3) o . A zinc complex of this ligand was prepared through direct reaction at room temperature. All effort to produce high quality crystals was unsuccessful; however, it shows consistent spectral results with the ligand except in the position of azomethine which may be due to complexation. Both the ligand and its zinc complex were screened and evaluated for anti-ulcer activity against ethanol induced gastric ulceration. The result has shown that, a...

N 4 O 3 tripodal Schiff-base ligand namely tris(5-Bromo-2-hydroxybenzylaminoethyl)amine (Tren5BrSal) have been prepared and characterized by various spectroscopic methods . It is derived from the condensation reactions of tris(2-aminoethyl)amine (Tren), with 3 equivalents of 5-bromo-2-hydroxybenzaldehyde (5BrSal). The Cobalt(III) complex of the resulting ligand was obtained from the reaction of Tren5BrSal with the salt of  cobalt in absolute methanol. The antimicrobial screening was carried out against two bacterial species ( Escherichia coli and Streptococc. Sp) and two fungal species ( Aspergillus niger and Fusarium sp.) . The complex is found to exhibit high antibacterial and anti fungal activity. Keywords: Schiff- base, tris-(2-aminoethyl)amine, Tren5Brsal, Cobalt.