Borohidreto complexos de cobre (I) contendo difosfinas: caracterização espectroscópica e comportamento térmico

Tetrahydroborate complexes of copper (I) with bidentate phosphines, [Cu(eta²-BH4)(dppm)] (1), [Cu(eta²-BH4)(dppe)] (2), [Cu(eta²-BH4)(cis-dppet)] (3) and [Cu(eta²-BH4)(dppb)] (4) (dppm = bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino) ethane; cis-dppet = 1,2-cis(diphenylphosphino)ethene; dppb = 1,4-bis(diphenylphosphino)butane) were prepared and characterized by elemental analysis, infrared spectroscopy, NMR and thermogravimetric analysis. The IR data for 1-4 showed bands typical of a bidentate coordination of BH4 group to the copper atom and the 31P{¹H} NMR spectra indicated that the phosphorous atoms are chelating the metal centre. The thermal behavior of the compounds was investigated and suggested that their thermal stability is influenced by the phosphines. Their thermal stability decreased as follows: [Cu(eta²-BH4)(dppe)] (2) > [Cu(eta²-BH4)(dppm)] (1) > [Cu(eta²-BH4)(dppb)] (4) > [Cu(eta²-BH4)(cis-dppet)] (3). According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving Cu(BO2)2, CuO, CuO2 and Cu as final products.

Reação de bis-inserção de 1,2-difenilacetileno na ligação Pd-C de ciclometalados

The present paper deals with the bis-insertion reactions of 1,2-diphenylacetylene into Pd-C bond of the cyclopalladated complexes [Pd(dmba)(µ-NCO)]2 (1) and [Pd(dmba)(MeCN)2](NO3) (2) (dmba = N,N-dimethylbenzylamine, MeCN = acetonitrile). Two new complexes [Pd{PhC=CPh-CPh=CPhC6H4CH2N(CH 3)2}(NCO)] (3) and [Pd{PhC=CPh-CPh=CPhC6H4CH2N(CH 3)2}(NO3 )] (4) were obtained and characterized by IR and NMR spectroscopy and elemental analysis.

Syntheses, characterization and antifungal activity of tris(1,10-phenanthroline)iron(ii) bis(n-r-sulfonyldithiocarbimate)zincate(ii)

Four new compounds with the general formula [Fe(phen)3][Zn(RSO2N=CS2)2], where phen = 1,10-phenanthroline, R = 4-FC6H4 (1), 4-ClC6H4 (2), 4-BrC6H4 (3) and 4-IC6H4 (4), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2N=CS2K2) and tris(1,10-phenanthroline)iron(II) sulfate, with zinc(II) acetate dihydrate in dimethylformamide. The elemental analyses and the IR data were consistent with the formation of the expected complexes salts. The ¹H and 13C NMR spectra showed the signals for the cationic iron(II) complex and dithiocarbimate moieties. The molar conductance data were consistent with the 1:1 cation:anion complexes in 1-4. The antifungal activities of the compounds were tested in vitro against Candida albicans, Candida tropicalis and Colletotrichum gloeosporioides.

Fotoquímica e fotofísica do ácido 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno

Este trabalho versa sobre a caracterização espectroscópica do ácido 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno, substância com potencialidade em complexação de íons metálicos. Para isto foram obtidos espectros de UV/VIS do composto em meio aquoso na presença e ausência de irradiação no ultra-violeta. Foram obtidos um coeficiente de extinção molar de 36.457 L mol-1 cm-1 e uma taxa de degradação de 5,2.10-7 mol L-1 min-1, quando se irradiou uma solução do composto cuja concentração era de 3,2.10-5 mol L-1 em uma cubeta de quartzo de 10mm de caminho ótico a 7,0cm de uma lâmpada de mercúrio de 80W.

Estudo do comportamento térmico dos compostos de Ag+ e Pb2+ com o ligante 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno

Este trabalho reporta o estudo de compostos binários do dicarboxilato 1,4-bis(3-carbóxi-3-oxo-prop-1-enil)benzeno, C6H4(-CH=CH-CO-COO-)2 , com os cátions metálicos Ag+ e Pb2+, obtidos a partir de soluções aquosas do ligante e dos nitratos dos cátions metálicos, em proporções estequiométricas. Para a caracterização e o estudo do processo de decomposição térmica desses compostos foram empregadas Espectrofotometria de Absorção na Região do Infravermelho com Transformada de Fourier (FT-IR), Análise Elementar (C, H), Complexometria com EDTA, Termogravimetria (TG) e Calorimetria Exploratória Diferencial (DSC).

Biheterocyclic ligands: synthesis, characterization and coordinating properties of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes with transition metal ions and their thermokinetic and biological studies

The Co(II), Ni(II) and Cu(II) metal ions complexes of Bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes (BATs) have been prepared and characterized by elemental analysis, conductivity measurements infrared, magnetic susceptibility, the electronic spectral data and thermal studies. Based on spectral and magnetic results, the ligands are tetradentate coordinating through the N and S-atoms of BATs; six-coordinated octahedral or distorted octahedral and some times four-coordinated square planar were proposed for these complexes. Activation energies computed for the thermal decomposition steps were compared. The ligands and their metal complexes were tested in vitro for their biological effects. Their activities against two gram-positive, two gram-negative bacteria and two fungal species were found to vary from moderate to very strong.

In vitro activity of 1,3-bisaryloxypropanamines against Trypanosoma cruzi-infected L929 cultures

We describe herein the antitrypanosomal activity of 20 novel 1,3-bis(aryloxy)propan-2-amine derivatives. Compounds 2, 4, 6, 12, 15, 16 and 19 were significantly active against amastigote and trypomastigote forms, with half maximal inhibitory concentrationvalues in the range of 6-18 µM. In the cytotoxicity tests against L929 cells, only compound 4 presented selectivity index value above 10, indicating low toxicity.

Derivados organometálicos de estanho(II) - Parte 1. Compostos ciclopentadienílicos

This paper provides a brief review of the chemistry of cyclopentadienyl Sn(II) derivatives which includes the preparation, the molecular structure and reactivity associated with such bis-sandwich tin(II) species. It is compared structural and spectroscopic results and it is also discussed how the nature of the cyclopentadienyl ring bonded to the Sn centre plays an important role in the structural and stability features of the derivatives. Bulk rings such as C5HPr i4- , C5Bz5-, C5Me4SiMe2Bu t- and C5Ph5- render air-stable and parallel ring-bonded compounds.

AVALIAÇÃO DO RADICAL N,N-DIETIL-1,4-FENILENODIAMINO (DEPD•+) COMO SONDA ESPECTROFOTOMÉTRICA PARA DETERMINAÇÃO DA CAPACIDADE ANTIOXIDANTE EM BEBIDAS

AbstractMany well-established methods for determining the antioxidant capacities in several samples have been described in literature. However, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) are the main two methods that utilize radicals as spectrophotometric probes for analysis. Nevertheless, these methods have certain limitations because of their slower kinetics, solvent polarity effects, the hydrophilicity and lipophilicity of the compounds, chemical costs, etc. In this study, a spectrophotometric method for determining the antioxidant capacity in beverages was developed based on an exploration of the cation radical derived from DEPD. This method was based on the oxidation of aromatic amines with Fe(III) ions at pH 4.0, which leads to their corresponding purple cation radicals (DEPD•+) with λmax values at 500 and 540 nm. The addition of an antioxidant after the formation of the radical leads to a reduction in color intensity that is proportional to the antioxidant concentration in the medium. Results obtained using this method were compared with the Folin-Ciocalteau, ABTS and DPPH methods in terms of applications in wines, teas, and infusions samples. Linear correlation analysis at a 95% confidence level was employed to compare the results, which were in good agreement with a correlation coefficient of r > 0.9000. Thus, the developed method was simple, accurate, and consistent with other assays for the determination of the total amount of phenolic compounds and antioxidant capacity.

Electrochemical properties of Cu4[PhN3C6H4N3(H)Ph]4(µ-O)2, a tetranuclear Copper(II) complex with 1-phenyltriazenido-2-phenyltriazene-benzene as ligand

Bis-(µ2-oxo)-tetrakis{[1-feniltriazene-1,3-diil)-2-(phenyltriazenil)benzene copper(II) is a tetranuclear complex which shows four Cu(II) ions coordinated by four 1,2-bis(phenyltriazene)benzene bridged ligands, with one diazoaminic deprotonated chain, and two O2- ligands. The complex reduces at E1/2 = -0.95 V vs Fc+/Fc, a two electrons process. Cyclic voltammetric and spectroelectrochemical studies showed a reversible process. When immobilized on carbon paste electrode, the complex electrocatalyses the reduction of O2 dissolved on aqueous solution at -0.3 V vs SCE potential. The obtained current shows linearity with O2 concentration.