Spectral properties of some metal complexes derived from uracil-thiouracil and citrazinic acid compounds.

The reaction of FeCl(3) with uracil (H(2)L(1)), citrazinic acid (H(2)L(6)), 5-(phenylazo)citrazinic acid (H(2)L(7)), 5-(m-hydroxyphenylazo)citrazinic acid (H(2)L(8)) and 5-(m-nitrophenylazo)citrazinic acid (H(2)L(9)) leads to the formation of complexes with the empirical formula Fe(HL)(3).nH(2)O (n=1-3). All of the prepared complexes have octahedral complexation geometry where the azo group is not the reactive site for complexation. Thiouracil (H(2)L(2)) and the 5-(substituted phenylazo)thiouracil (H(2)L(3)-H(2)L(5)) ligands are bidentates on complexation with Co(II), Ni(II) and Cu(II). The complexes have been characterized by elemental analyses, IR, electronic spectra, magnetic susceptibility, DTA, electron spin resonance (copper complexes) and Mössbauer spectra (iron complexes). The coordination bond lengths between the metal ion and the active centers for complexation were calculated.

Spectral, electrical conductivity and biological activity properties of some new azopyrimidine derivatives and their complexes.

The electronic absorption spectra of 5-(o-substituted phenylazo)-6-amino-2-thiouracils and 6-(o-substituted phenylazo)-5-aminouracils containing different substituents are studied at different pH's. The dissociation constants are evaluated and discussed. Phenomenon of tautomerism is more supported by (1)H NMR and (13)C NMR spectra. The electrical conductivity of some ligands and their Co(II), Ni(II) and Cu(II) complexes in the temperature range 293-150K favoured their semiconducting properties where the metal ion forms a bridge to facilitate the flow of the current. The biological activity of some ligands and their complexes are tested against a number of Gram-positive and Gram-negative bacteria. The results showed that some of the compounds have a well considerable activity against some of the organisms.

Complexing properties of some pyrimidines.

The synthesis of transition metal barbiturate, and thiobarbiturate complexes containing different functional groups of variable electronic character with CoII, NiII, CuII, PdII, and PtII have been prepared. The stereochemistry and the mode of bonding of the complexes were determined by elemental analysis and electronic and vibrational spectra together with their magnetic moment values. Electronic spin resonance of copper complexes were recorded. The Racah parameter of some cobalt and nickel complexes were calculated. Some of the complexes are of mixed stereochemistry. All the PdII or PtII complexes are of square planar geometries.

Spectroscopic studies on some azo compounds and their cobalt, copper and nickel complexes.

Synthesis and characterization of [o-carboxy phenylazo] moiety of barbituric acid, thiobarbituric acid, thiouracil, citrazinic acid, and disodium chromotropate and their complexes derived from cobalt (II), nickel (II), and copper (II) salts were done. The stereochemistry and the mode of bonding of the complexes were achieved based on elemental analysis, NMR, UV-Vis, IR and ESR. The dissociation constants of the free azo ligands are evaluated by spectrophotometric methods.