Propriedades espectroscópicas e parâmetros ópticos-eletrônicos dos complexos Ln(NO3)3.2DTPO.4H2O (Ln = Nd e Er)

Complexes with the composition Ln(NO3)3.2DTPO.4H2O (Ln = Nd and Er) were synthesized and characterized by infrared and visible absorption spectra (solid state and solution). The results of the absorption spectra in the solid state suggest that metal-ligand bonds are essentially electrostatic in all complexes. The absorption spectra of the nitrate salt solution presented smaller values of the oscillator strength when compared to the spectra of the complexes in the same solvent.

Avaliação dos parâmetros ópticos-eletrônicos do íon Nd3+nos compostos Nd(TMS)3.9H2O e Nd(TMS)(3)5BPMU.2H2O em solução

A polarizabilidade representa a facilidade de distorção da configuração eletrônica de uma espécie, quando condicionada a interação de um campo elétrico. A diversidade de aplicações tem motivado experimentos sistemáticos para a obtenção dos valores de polarizabilidade dipolo. Neste trabalho foram avaliados os parâmetros ópticos e polarizabilidades eletrônicas dos compostos Nd(TMS)3.9H2O e Nd(TMS)(3)5BPMU.2H2O, onde TMS = trifluorometanossulfonato e BPMU = bis(pentametileno)uréia, na presença dos solventes acetonitrila e metanol. Foram registrados os espectros nas regiões referente as transições hipersensitivas 4I9/2 -> 4G7/2, ²G9/2 e 4I9/2 -> 4G5/2, ²G7/2. Em ambas as transições, quando o meio é acetonitrila, os compostos apresentam valores de polarizabilidades mais elevados, resultantes de uma maior interação do ambiente químico em torno do íon central, favorecido por este solvente.

Complexes of 3,4-dimethoxybenzoic acid anion with Cu(II), Co(II), La(III), and Nd(III)

Physico-chemical properties of 3,4-dimethoxybenzoates of Co(II), Cu(II), La(III) and Nd(III) were studied. The complexes were obtained as hydrated or anhydrous polycrystalline solids with a metal ion-ligand mole ratio of 1 : 2 for divalent ions and of 1 : 3 in the case of trivalent cations. Their colours depend on the kind of central ion: pink for Co(II) complex, blue for Cu(II), white for La(III) and violet for Nd(III) complexes. The carboxylate groups in these compounds are monodentate, bidentate bridging or chelating and tridentate ligands. Their thermal decomposition was studied in the range of 293-1173 K. Hydrated complexes lose crystallization water molecules in one step and form anhydrous compounds, that next decompose to the oxides of respective metals. 3,4 - Dimethoxybenzoates of Co(II) is directly decomposed to the appropriate oxide and that of Nd(III) is also ultimately decomposed to its oxide but with the intemediate formation of Nd2O2CO3.. The magnetic moment values of 3,4-dimethoxybenzoates determined in the range of 76-303 K change from 4.22 µB to 4.61 µB for Co(II) complex , from 0.49 µB to 1.17 µB for Cu(II) complex , and from 2.69 µB to 3.15 µB for Nd(III) complex.

Comparison of some properties of 2,3 - and 3,4 - dimethoxybenzoates of Cu(II), Co(II) and Nd(III)

The physicochemical properties of 2,4-, and 3,4- dimethoxybenzoates of Cu(II), Co(II) and Nd(III) were studied and compared to observe the -OCH3 substituent positions in benzene ring on the character of complexes. The analysed compounds are crystalline hydrated or anhydrous salts with colours depending on the kind of central ions: blue for Cu(II), pink for Co(II) and violet for Nd(III) complexes. The carboxylate groups bind as monodentate, bidentate bridging or chelating and even tridentate ligands. Their thermal stabilities were studied in air at 293-1173K. When heated the hydrated complexes release the water molecules and form anhydrous compounds which are then decomposed to the oxides of respective metals. Their magnetic moment values were determined in the range of 76-303K. The results reveal the compounds of Nd(III) and Co(II) to be the high-spin and that of Cu(II) forms dimer. The various positions of -OCH3 groups in benzene ring influence some of physicochemical properties of analysed compounds.

Complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III)

The complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) have been synthesized as polycrystalline hydrated solids, and characterized by elemental analysis, spectroscopy, magnetic studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: violet for Nd(III), white for Gd(III) and cream for Ho(III) compounds. The carboxylate groups bind as bidentate chelating (Ho) or bridging ligands (Nd, Gd). On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to form anhydrous salts, that next decompose to the oxides of respective metals. The gaseous products of their thermal decomposition in nitrogen were also determined and the magnetic susceptibilites were measured over the temperature range of 76-303K and the magnetic moments were calculated. The results show that 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) are high-spin complexes with weak ligand fields. The solubility value in water at 293K for analysed 4-chlorophenoxyacetates is in the order of 10-4mol/dm³.

Kinetics of epsilon antitoxin antibodies in different strategies for active immunization of lambs against enterotoxaemia

Enterotoxaemia, a common disease that affects domestic small ruminants, is mainly caused by the epsilon toxin of Clostridium perfringens type D. The present study tested four distinct immunization protocols to evaluate humoral response in lambs, a progeny of non-vaccinated sheep during gestation. Twenty-four lambs were randomly allocated into four groups according to age (7, 15, 30 and 45 days), receiving the first dose of epsilon toxoid commercial vaccine against clostridiosis with booster after 30 days post vaccination. Indirect ELISA was performed after the first vaccine dose and booster to evaluate the immune response of the lambs. Results showed that for the four protocols tested all lambs presented serum title considered protective (≥0.2UI/ml epsilon antitoxin antibodies) and also showed that the anticipation of primovaccination of lambs against enterotoxaemia conferred serum title considered protective allowing the optimization of mass vaccination of lambs.