948 resultados para 10-DEACETYL BACCATIN III


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Trägerband: Ms. Barth. 56; Vorbesitzer: Johann Qwentin von Ortenberg; Jungo Frosch; Bartholomaeusstift Frankfurt am Main

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Trägerband: Ms. Barth. 10; Vorbesitzer: Johannes Pincerna de Erbach; Bartholomaeusstift Frankfurt am Main

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Trägerband: Inc. oct. 473; 'Homil. cath. 686a'; Vorbesitzer: Dominikanerkloster Frankfurt am Main

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Fedro realiza a lo largo de su obra un esfuerzo consciente y prolongado por obtener un lugar, que cree merecido, como recreador latino del género fabulístico. A partir del epílogo del L. II de sus Fábulas, el poeta da cuenta de un cambio en su posición como escritor y un incremento de la recepción de su obra en los círculos letrados. En el prólogo del L. IV declara que su esfuerzo se ha visto recompensado, porque ya sus obras eran copiadas y leídas. Por su parte Ovidio en Tr. 4, 10 declara que, gracias a la Musa, tiene un lugar destacado en el Helicón e, inmune a la Envidia, ha conseguido en vida un renombre por su obra. En esta ponencia, mediante la identificación de recurrencias léxicas y analogías estructurales, se explora la posible incidencia de Ov. Tr. 4, 10 en algunos prólogos y epílogos fedrianos, tomando como centro los del L. III, donde se encuentran condensadas las reflexiones del poeta acerca de supropia escritura, de su imagen como escritor y la preocupación por los ataques de la Envidia, representada por sus críticos y detractores.

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Fedro realiza a lo largo de su obra un esfuerzo consciente y prolongado por obtener un lugar, que cree merecido, como recreador latino del género fabulístico. A partir del epílogo del L. II de sus Fábulas, el poeta da cuenta de un cambio en su posición como escritor y un incremento de la recepción de su obra en los círculos letrados. En el prólogo del L. IV declara que su esfuerzo se ha visto recompensado, porque ya sus obras eran copiadas y leídas. Por su parte Ovidio en Tr. 4, 10 declara que, gracias a la Musa, tiene un lugar destacado en el Helicón e, inmune a la Envidia, ha conseguido en vida un renombre por su obra. En esta ponencia, mediante la identificación de recurrencias léxicas y analogías estructurales, se explora la posible incidencia de Ov. Tr. 4, 10 en algunos prólogos y epílogos fedrianos, tomando como centro los del L. III, donde se encuentran condensadas las reflexiones del poeta acerca de supropia escritura, de su imagen como escritor y la preocupación por los ataques de la Envidia, representada por sus críticos y detractores.

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Fedro realiza a lo largo de su obra un esfuerzo consciente y prolongado por obtener un lugar, que cree merecido, como recreador latino del género fabulístico. A partir del epílogo del L. II de sus Fábulas, el poeta da cuenta de un cambio en su posición como escritor y un incremento de la recepción de su obra en los círculos letrados. En el prólogo del L. IV declara que su esfuerzo se ha visto recompensado, porque ya sus obras eran copiadas y leídas. Por su parte Ovidio en Tr. 4, 10 declara que, gracias a la Musa, tiene un lugar destacado en el Helicón e, inmune a la Envidia, ha conseguido en vida un renombre por su obra. En esta ponencia, mediante la identificación de recurrencias léxicas y analogías estructurales, se explora la posible incidencia de Ov. Tr. 4, 10 en algunos prólogos y epílogos fedrianos, tomando como centro los del L. III, donde se encuentran condensadas las reflexiones del poeta acerca de supropia escritura, de su imagen como escritor y la preocupación por los ataques de la Envidia, representada por sus críticos y detractores.

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The mixed double-decker Eu\[Pc(15C5)4](TPP) (1) was obtained by base-catalysed tetramerisation of 4,5-dicyanobenzo-15-crown-5 using the half-sandwich complex Eu(TPP)(acac) (acac = acetylacetonate), generated in situ, as the template. For comparative studies, the mixed triple-decker complexes Eu2\[Pc(15C5)4](TPP)2 (2) and Eu2\[Pc(15C5)4]2(TPP) (3) were also synthesised by the raise-by-one-story method. These mixed ring sandwich complexes were characterised by various spectroscopic methods. Up to four one-electron oxidations and two one-electron reductions were revealed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). As shown by electronic absorption and infrared spectroscopy, supramolecular dimers (SM1 and SM3) were formed from the corresponding double-decker 1 and triple-decker 3 in the presence of potassium ions in MeOH/CHCl3.

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The electrochemical characteristics of a series of heteroleptic tris(phthalocyaninato) complexes with identical rare earths or mixed rare earths (Pc)M(OOPc)M(OOPc) [M = Eu...Lu, Y; H2Pc = unsubstituted phthalocyanine, H2(OOPc) = 3,4,12,13,21,22,30,31-octakis(octyloxy)phthalocyanine] and (Pc)Eu(OOPc)Er(OOPc) have been recorded and studied comparatively by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M tetrabutylammonium perchlorate (TBAP). Up to five quasi-reversible one-electron oxidations and four one-electron reductions have been revealed. The half-wave potentials of the first, second and fifth oxidations depend on the size of the metal center, but the fifth changes in the opposite direction to that of the first two. Moreover, the difference in redox potentials of the first oxidation and first reduction for (Pc)M(OOPc)M(OOPc), 0.85−0.98 V, also decreases linearly along with decreasing rare earth ion radius, clearly showing the rare earth ion size effect and indicating enhanced π−π interactions in the triple-deckers connected by smaller lanthanides. This order follows the red-shift seen in the lowest energy band of triple-decker compounds. The electronic differences between the lanthanides and yttrium are more apparent for triple-decker sandwich complexes than for the analogous double-deckers. By comparing triple-decker, double-decker and mononuclear [ZnII] complexes containing the OOPc ligand, the HOMO−LUMO gap has been shown to contract approximately linearly with the number of stacked phthalocyanine ligands.

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A combination of X-ray diffraction, thermal analysis and Raman spectroscopy was employed to characterise the ageing of alumina hydrolysates synthesised from the hydrolysis of anhydrous tri-sec-butoxyaluminium(III). X-Ray diffraction showed that the alumino-oxy(hydroxy) hydrolysates were pseudoboehmite. For boehmite the lamellar spacings are in the b direction and multiple d(020) peaks are observed for the un-aged hydrolysate. After 4 h of ageing, a single d(020) peak is observed at 6.53 Å. Thermal analysis showed five endotherms at 70, 140, 238, 351 and 445°C. These endotherms are attributed to the dehydration and dehydroxylation of the boehmite-like hydrolysate. Raman spectroscopy shows the presence of bands for the washed hydrolysates at 333, 355, 414, 455, 475, 495, 530 and 675 cm–1. These bands are attributed to pseudoboehmite. Ageing of the hydrolysates results in an increase in the crystallite size of the pseudoboehmite.

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The electrochemistry of homoleptic substituted phthalocyaninato rare earth double-decker complexes M(TBPc)2 and M(OOPc)2 [M = Y, La...Lu except Pm; H2TBPc = 3(4),12(13),21(22),30(31)-tetra-tert-butylphthalocyanine, H2OOPc = 3,4,12,13,21,22,30,31-octakis(octyloxy)phthalocyanine] has been comparatively studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). Two quasi-reversible one-electron oxidations and three or four quasi-reversible one-electron reductions have been revealed for these neutral double-deckers of two series of substituted complexes, respectively. For comparison, unsubstituted bis(phthalocyaninato) rare earth analogues M(Pc)2 (M = Y, La...Lu except Pm; H2Pc = phthalocyanine) have also been electrochemically investigated. Two quasi-reversible one-electron oxidations and up to five quasi-reversible one-electron reductions have been revealed for these neutral double-decker compounds. The three bis(phthalocyaninato)cerium compounds display one cerium-centered redox wave between the first ligand-based oxidation and reduction. The half-wave potentials of the first and second oxidations and first reduction for double-deckers of the tervalent rare earths depend on the size of the metal center. The difference between the redox potentials of the second and third reductions for MIII(Pc)2, which represents the potential difference between the first oxidation and first reduction of [MIII(Pc)2]−, lies in the range 1.08−1.37 V and also gradually diminishes along with the lanthanide contraction, indicating enhanced π−π interactions in the double-deckers connected by the smaller, lanthanides. This corresponds well with the red-shift of the lowest energy band observed in the electronic absorption spectra of reduced double-decker [MIII(Pc′)2]− (Pc′ = Pc, TBPc, OOPc).

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The infrared (IR) spectroscopic data and Raman spectroscopic properties for a series of 13 “pinwheel-like” homoleptic bis(phthalocyaninato) rare earth complexes M[Pc(α-OC5H11)4]2 [M = Y and Pr–Lu except Pm; H2Pc(α-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine] have been collected and comparatively studied. Both the IR and Raman spectra for M[Pc(α-OC5H11)4]2 are more complicated than those of homoleptic bis(phthalocyaninato) rare earth analogues, namely M(Pc)2 and M[Pc(OC8H17)8]2, but resemble (for IR) or are a bit more complicated (for Raman) than those of heteroleptic counterparts M(Pc)[Pc(α-OC5H11)4], revealing the decreased molecular symmetry of these double-decker compounds, namely S8. Except for the obvious splitting of the isoindole breathing band at 1110–1123 cm−1, the IR spectra of M[Pc(α-OC5H11)4]2 are quite similar to those of corresponding M(Pc)[Pc(α-OC5H11)4] and therefore are similarly assigned. With laser excitation at 633 nm, Raman bands derived from isoindole ring and aza stretchings in the range of 1300–1600 cm−1 are selectively intensified. The IR spectra reveal that the frequencies of pyrrole stretching and pyrrole stretching coupled with the symmetrical CH bending of –CH3 groups are sensitive to the rare earth ionic size, while the Raman technique shows that the bands due to the isoindole stretchings and the coupled pyrrole and aza stretchings are similarly affected. Nevertheless, the phthalocyanine monoanion radical Pc′− IR marker band of bis(phthalocyaninato) complexes involving the same rare earth ion is found to shift to lower energy in the order M(Pc)2 > M(Pc)[Pc(α-OC5H11)4] > M[Pc(α-OC5H11)4]2, revealing the weakened π–π interaction between the two phthalocyanine rings in the same order.