Complexation of lanthanides, actinides and transition metal cations with a 6-(1,2,4-triazin-3-yl)-2,2’:6’,2’’-terpyridine ligand: implications for actinide(III) /lanthanide(III) partitioning

The quadridentate N-heterocyclic ligand 6-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2’:6’,2’’-terpyridine (CyMe4-hemi-BTBP) has been synthesized and its interactions with Am(III), U(VI), Ln(III) and some transition metal cations have been evaluated by X-ray crystallographic analysis, Am(III)/Eu(III) solvent extraction experiments, UV absorption spectrophotometry, NMR studies and ESI-MS. Structures of the 1:1 complexes with Eu(III), Ce(III) and the linear uranyl (UO22+) ion were obtained by X-ray crystallographic analysis, and showed similar coordination behavior to related BTBP complexes. In methanol, the stability constants of the Ln(III) complexes are slightly lower than those of the analogous quadridentate bis-triazine BTBP ligands, while the stability constant for the Yb(III) complex is higher. 1H NMR titrations and ESI-MS with lanthanide nitrates showed that the ligand forms only 1:1 complexes with Eu(III), Ce(III) and Yb(III), while both 1:1 and 1:2 complexes were formed with La(III) and Y(III) in acetonitrile. A mixture of isomeric chiral 2:2 helical complexes was formed with Cu(I), with a slight preference (1.4:1) for a single directional isomer. In contrast, a 1:1 complex was observed with the larger Ag(I) ion. The ligand was unable to extract Am(III) or Eu(III) from nitric acid solutions into 1-octanol, except in the presence of a synergist at low acidity. The results show that the presence of two outer 1,2,4-triazine rings is required for the efficient extraction and separation of An(III) from Ln(III) by quadridentate N-donor ligand

Que é a "História do Espírito" (Geistesgeschichte)?

Hans-Joachim Schoeps é professor da Universidade de Erlangen. Historiador das religiões e especialista principalmente da história das origens cristãs, fundou além disso um Centro para o estudo da História do Espírito (Geistesgeschichte). Foi o primeiro a organizar sistemàticamente essa disciplina (1947), que ensina num curso cíclico de seis semestres sob o título de "Introdução à história do espírito na Alemanha moderna" (Ein-führung in die deutsche Geistesgeschichte der Neuzeit). Já percorreu três vêzes êsse ciclo

Vaticano II, cincuenta años después (Vatican II, fifty years later) - DOI: 10.5752/P.2175-5841.2011v9n24p1207

ResumenEl artículo parte de una situación que tendrá gran importancia para la posterior evolución del Concilio en la Iglesia: la existencia de una minoría conciliar conservadora, representada por la Curia Romana, estratégicamente presente en las comisiones preparatorias. De las tensiones entre renovadores y conservadores, resultaron documentos ambiguos, anunciando temas nuevos, a los que se contraponían viejas facetas de la tradición papal. Paralelamente a lo que el Concilio representó en términos de renovación de la Iglesia, el artículo traza el perfil de otro cambio ocurrido en la historia do Occidente: la revolución cultural, simbólicamente representada por 1968. Esta significó la crítica radical a todas las instituciones establecidas y de todos los sistemas de autoridad. Con relación a la Iglesia, la revolución cultural (marcada, entre otras cosas, por el descubrimiento de la píldora anticonceptiva y por la explosión feminista) puso en jaque sus dogmas y valores. Concomitantemente, los cambios en el modo de producción capitalista caminaban en dirección a la desvalorización del trabajo y a la exacerbación del consumo. En crisis y desprestigiada por el  impacto de los cambios culturales, la Iglesia reaccionó con el “retorno a la grande disciplina”. En América Latina, donde la recepción del Concilio prometía frutos auspiciosos, quedan tímidas reformas. Frente a todo esto, la reflexión propuesta por el artículo señala caminos de esperanza para la vivencia de la fe.Palabras Clave: Iglesia. Concilio Vaticano II. Curia Romano. Revolución cultural. 1968. AbstractThis article starts from a situation of great importance in the subsequent evolution of the Council within the Church: the existence of conservative minority represented by the Roman Curia, strategically present within the preparatory commissions. Tensions between reformers and conservatives led to ambiguous documents and announced new issues to which the papal tradition was opposed. Next to the Council represented in terms of renewal of the Church, the article traces the profile of another change that took place in Western history: the Cultural Revolution represented symbolically by 1968. The revolution meant a radical critique of all established institutions, and all systems of authority. The Cultural Revolution (marked by the discovery of the pill and the feminist explosion) also put into question the dogmas and values of the Church. Concomitantly, changes in the capitalist mode of production devaluated the work and encouraged consumption. In crisis and discredited by the impact of cultural changes, the Church responded with a “return to the great discipline”. In Latin America, where the reception of the Council promised auspicious fruits, timid reforms remained. Given this, the reflection proposed by the article points out the way of hope for living the faith.Keywords: Church. Vatican II. Roman Curia. Cultural Revolution. 1968.- DOI: 10.5752/P.2175-5841.2011v9n24p120

A virada da Teologia Cristã

A teologia cristã nasceu no século XIII sob o impulso dos filósofos gregos. O texto faz, de maneira crítica, a história da teologia, mostrando que ela sempre quis atingir a realidade através de conceitos abstratos e raciocínios lógicos. No entanto, ouvir a Palavra de Deus sempre exigiu compreender e seguir a vida de Jesus e a de seus discípulos, olhando a realidade da humanidade no tempo presente. Segue a longa história do legado da teologia cristã fazendo-se notar que hoje, numa Igreja missionária, evangelizadora, há falta de coragem para se fazer as mudanças necessárias

Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate

In this paper we report the synthesis and the characterization of the novel ligand H5EPTPA-C16 ((hydroxymethylhexadecanoyl ester)ethylenepropylenetriaminepentaacetic acid). This ligand was designed to chelate the GdIII ion in a kinetically and thermodynamically stable way while ensuring an increased water exchange rate (kex) on the GdIII complex due to steric compression around the water binding site. The attachment of a palmitic ester unit to the pendant hydroxymethyl group on the ethylenediamine bridge yields an amphiphilic conjugate that forms micelles in aqueous solution with a long tumbling time (R). The critical micelle concentration (CMC = 0.34 mM) of the amphiphilic [Gd(EPTPA-C16)(H2O)]2- chelate was determined by variable concentration proton relaxivity measurements. A global analysis of the data obtained in variable temperature and multiple field 17O NMR, and 1H NMRD measurements allowed the determination of parameters governing relaxivity for [Gd(EPTPA-C16)(H2O)]2-; this is the first time that paramagnetic micelles with optimized water exchange are investigated. The water exchange rate was found to be kex298 = 1.7×108 s-1, very similar to that previously reported for the nitrobenzyl derivative [Gd(EPTPA-bz-NO2)(H2O)]2- (kex298 = 1.5×108 s-1). The rotational dynamics of the micelles was analysed using the Lipari-Szabo approach. The micelles formed in aqueous solution show a considerable flexibility, with a local rotational correlation time of the GdIII segments, lO298 = 330 ps, being much shorter than the global rotational correlation time of the supramolecular aggregates, gO298 = 2100 ps. This internal flexibility of the micelles is responsible for the only limited increase of the proton relaxivity observed on micelle formation (r1 = 22.59 mM-1s-1 for the micelles vs. 9.11 mM-1s-1 for the monomer chelate (20 MHz; 25°C)).Fundação para a Ciência e a Tecnologia (FCT) - POCTI/QUI/47005/2002). EU Cost Action D18 "Lanthanide chemistry for diagnosis and therapy". Swiss National Science Foundation. Swiss Federal Office for Education and Science