994 resultados para anomalous Eu3 5D0->F-7(0) transition


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Results on the luminescence properties of Eu3+ in Ba2SiO4 sites and the presence of Eu3+-O2- associates are reported. The Ba2SiO4:Eu3+ emission spectra showed two groups of transitions that might be assigned to the D-5(0) --> F-7(0) one. In each group at least two lines were observed. This is possibly related to the different emission centers, attributed to Eu3+ occupying the Ba2+ sites, and to Eu3+-O2- associates in interstices. Excitation spectra presented two CT bands at 270 and 340 nm related to each emission center.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Raman studies on Ca4Al2O5.7Fe2As2 superconductor in the temperature range of 5K to 300 K, covering the superconducting transition temperature T-c = 28.3 K, reveal that the Raman mode at similar to 230 cm(-1) shows a sharp jump in frequency by similar to 2% and linewidth increases by similar to 175% at T-o similar to 60 K. Below T-o, anomalous softening of the mode frequency and a large decrease by similar to 10 cm(-1) in the linewidth are observed. These precursor effects at T-0 (similar to 2T(c)) are attributed to significant superconducting fluctuations, possibly enhanced due to reduced dimensionality arising from weak coupling between the well separated (similar to 15 angstrom) Fe-As layers in the unit cell. A large blue-shift of the mode frequency between 300 K and 60 K (similar to 7%) indicates strong spin-phonon coupling in this superconductor. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4724206]

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Electroluminescence (EL) devices with Eu(HTH)(3)phen [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione, phen: I 10-phenanthroline] as an emissive centre were fabricated using vacuum evaporation. In addition to the Eu3+ 5D0 --> F-7(J) (J = 0-4) lines that were visible in the photoluminescence signal, the device also showed strong emission from the D-5(1) --> F-7(J) (J = 0-4) transitions. The enhanced emission from the D-5(1) F-7(J) (J = 0-4) transitions was attributed to the increased excitation intensity in the EL device. The luminescence lifetimes of the 5 D, and 5 Do levels were measured to be 0.6 mus and 866 mus, respectively.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We determine the nature of coupled phonons in mixed crystal of Cs-0.9(NH4)(0.1)H2AsO4 using inelastic light scattering studies in the temperature range of 5 K to 300 K covering a spectral range of 60-1100 cm(-1). The phase transition in this system are marked by the splitting of phonon modes, appearance of new modes and anomalies in the frequency as well as linewidth of the phonon modes near transition temperature. In particular, we observed the splitting of symmetric (v(1)) and antisymmetric (v(3)) stretching vibrations associated with AsO4 tetrahedra below transition temperature (T-c(*) similar to 110 K) attributed to the lowering of site symmetry of AsO4 in orthorhombic phase below transition temperature. In addition, the step-up (hardening) and step-down (softening) of the AsO4 bending vibrations (v(4) (S9, S11) and v(2) (S6)) below transition temperature signals the rapid development of long range ferroelectric order and proton ordering. The lowest frequency phonon (S1) mode observed at similar to 92 cm(-1) shows anomalous blue shift (similar to 12 %) from 300 K to 5 K with no sharp transition near T-c(*) unlike other observed phonon modes signaling its potential coupling with the proton tunneling mode. (C) 2013 Author(s).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

SrMoO4 doped with rare earth are still scarce nowadays and have attracted great attention due to their applications as scintillating materials in electro-optical like solid-state lasers and optical fibers, for instance. In this work Sr1-xEuxMoO4 powders, where x = 0.01; 0.03 and 0.05, were synthesized by Complex Polymerization (CP) Method. The structural and optical properties of the SrMoO4:Eu3+ were analyzed by powder X-ray diffraction patterns, Fourier Transform Infra-Red (FTIR), Raman Spectroscopy, and through Photoluminescent Measurements (PL). Only a crystalline scheelite-type phase was obtained when the powders were heat-treated at 800 A degrees C for 2 h, 2 theta = 27.8A degrees (100% peak). The excitation spectra of the SrMoO4:Eu3+ (lambda(Em.) = 614 nm) presented the characteristic band of the Eu3 + 5L6 transition at 394 nm and a broad band at around 288 nm ascribed to the charge-transfer from the O (2p) state to the Mo (4d) one in the SrMoO4 matrix. The emission spectra of the SrMoO4:Eu3+ powders (lambda(Exc.) = 394 and 288 nm) show the group of sharp emission bands among 523-554 nm and 578-699 nm, assigned to the D-5(1)-> F-7(0,1and 2) and D-5(0)-> F-7(0,1,2,3 and 4), respectively. The band related to the D-5(0)-> F-7(0) transition indicates the presence of Eu3+ site without inversion center. This hypothesis is strengthened by the fact that the band referent to the D-5(0)-> F-7(2) transition is the most intense in the emission spectra.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

<h3><img src="http://cover1.chaoxing.com//cover/Cover2.dll?iid=656563666a6a63646a6ba09b3037393038383534" border="0" alt="" hspace="6" width="150" height="213" align="left" /></h3><div class="partOrAll"><div class="abut_top part"> </div></div><div class="abut"></div><div class="abut_top partOrAlls"><p><a href="http://book.chaoxing.com/ebook/read_11266067_1.html" target="_blank"> </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_1.html" target="_blank"></a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_1.html" target="_blank">1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_1.html" target="_blank">1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_2.html" target="_blank">1.1</a></p><div class="allContent" style="display: block"><p><a href="http://book.chaoxing.com/ebook/read_11266067_6.html" target="_blank">1.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_10.html" target="_blank">1.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_13.html" target="_blank">1.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_17.html" target="_blank">1.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_21.html" target="_blank">2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_21.html" target="_blank">2.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_29.html" target="_blank">2.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_35.html" target="_blank">2.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_45.html" target="_blank">2.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_61.html" target="_blank">2.5 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_65.html" target="_blank">2.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_75.html" target="_blank">2.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_79.html" target="_blank">2.8</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_85.html" target="_blank">3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_85.html" target="_blank">3.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_89.html" target="_blank">3.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_94.html" target="_blank">3.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_103.html" target="_blank">3.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_115.html" target="_blank">4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_115.html" target="_blank">4.1 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_128.html" target="_blank">4.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_140.html" target="_blank">4.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_148.html" target="_blank">4.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_155.html" target="_blank">4.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_164.html" target="_blank">4.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_173.html" target="_blank">4.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_189.html" target="_blank">4.8</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_205.html" target="_blank">4.9</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_214.html" target="_blank">5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_214.html" target="_blank">5.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_224.html" target="_blank">5.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_230.html" target="_blank">5.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_234.html" target="_blank">5.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_239.html" target="_blank">6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_239.html" target="_blank">6.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_250.html" target="_blank">6.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_262.html" target="_blank">6.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_267.html" target="_blank">6.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_276.html" target="_blank">6.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_282.html" target="_blank">6.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_291.html" target="_blank">6.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_300.html" target="_blank">7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_300.html" target="_blank">7.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_304.html" target="_blank">7.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_310.html" target="_blank">7.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_314.html" target="_blank">7.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_318.html" target="_blank">7.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_325.html" target="_blank">8</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_325.html" target="_blank">8.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_335.html" target="_blank">8.2 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_339.html" target="_blank">8.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_345.html" target="_blank">8.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_351.html" target="_blank">8.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_358.html" target="_blank">9</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_358.html" target="_blank">9.1 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_364.html" target="_blank">9.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_370.html" target="_blank">9.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_378.html" target="_blank">9.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_382.html" target="_blank">9.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_388.html" target="_blank">9.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_392.html" target="_blank">9.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_397.html" target="_blank">9.8</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_405.html" target="_blank">1 0</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_405.html" target="_blank">10.1 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_410.html" target="_blank">10.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_416.html" target="_blank">10.3 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_422.html" target="_blank">10.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_425.html" target="_blank">10.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_434.html" target="_blank">1 1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_434.html" target="_blank">11.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_435.html" target="_blank">11.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_436.html" target="_blank">11.3 ANSYS</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_436.html" target="_blank">11.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_447.html" target="_blank">11.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_454.html" target="_blank">12</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_454.html" target="_blank">12.1 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_466.html" target="_blank">12.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_485.html" target="_blank">2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_485.html" target="_blank">13APDL</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_485.html" target="_blank">13.1 K</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_485.html" target="_blank">13.1.1 K</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_486.html" target="_blank">13.1.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_486.html" target="_blank">13.1.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_486.html" target="_blank">13.2APDL</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_487.html" target="_blank">13.2.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_487.html" target="_blank">13.2.2 ANSYS </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_488.html" target="_blank">13.2.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_490.html" target="_blank">13.3UIDL</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_490.html" target="_blank">13.3.1 </a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_490.html" target="_blank">13.3.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_491.html" target="_blank">13.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_491.html" target="_blank">13.4.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_491.html" target="_blank">13.4.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_493.html" target="_blank">13.4.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_494.html" target="_blank">13.4.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_494.html" target="_blank">13.4.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_495.html" target="_blank">13.4.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_495.html" target="_blank">13.4.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_496.html" target="_blank">13.4.8</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_499.html" target="_blank">13.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_499.html" target="_blank">13.5.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_499.html" target="_blank">13.5.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_501.html" target="_blank">13.5.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_501.html" target="_blank">13.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_501.html" target="_blank">13.6.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_501.html" target="_blank">13.6.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_502.html" target="_blank">13.6.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_502.html" target="_blank">13.6.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_503.html" target="_blank">14</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_503.html" target="_blank">14.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_503.html" target="_blank">14.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_505.html" target="_blank">14.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_506.html" target="_blank">14.3.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_506.html" target="_blank">14.3.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_506.html" target="_blank">14.3.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_506.html" target="_blank">14.3.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_507.html" target="_blank">14.3.5 4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_507.html" target="_blank">14.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_507.html" target="_blank">14.4.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_508.html" target="_blank">14.4.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_508.html" target="_blank">14.4.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_509.html" target="_blank">14.4.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_510.html" target="_blank">14.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_516.html" target="_blank">14.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_519.html" target="_blank">14.7</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_536.html" target="_blank">15</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_536.html" target="_blank">15.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_536.html" target="_blank">15.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_537.html" target="_blank">15.3SHELL51</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_537.html" target="_blank">15.3.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_539.html" target="_blank">15.3.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_542.html" target="_blank">15.3.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_544.html" target="_blank">15.3.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_546.html" target="_blank">15.3.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_546.html" target="_blank">15.3.6</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_550.html" target="_blank">15.482DPLANE82</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_551.html" target="_blank">15.4.1</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_551.html" target="_blank">15.4.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_558.html" target="_blank">15.4.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_559.html" target="_blank">15.4.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_560.html" target="_blank">15.5203Dsolid951/4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_560.html" target="_blank">15.5.11/4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_561.html" target="_blank">15.5.2</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_567.html" target="_blank">15.5.3</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_570.html" target="_blank">15.5.4</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_571.html" target="_blank">15.5.5</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_573.html" target="_blank"></a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_573.html" target="_blank">A</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_606.html" target="_blank">B</a></p><p><a href="http://book.chaoxing.com/ebook/read_11266067_647.html" target="_blank"></a></p></div></div>

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The foil-excited the spectrum of highly stripped titanium ions between 12-40 nm has been studied. Titanium ions of 80 and 120 MeV were provided by the HI-13 tandem accelerator at the China Institute of Atomic Energy. GIM-957 XUV-VUV monochromator was refocused to get highly-resolved spectra. Our experimental results and the published spectral data of laser-produced plasma show agreement in nearly all cases within +/- 0.03 nm. The spectra contained some weak or strong lines previously unclassified. These spectral lines mainly belong to 2s2p(2) for TiXVIII, 2p(3) for TiXVIII, 2s2p(3) for TiXVII, 2p(6)4p for Ti XII and 2p(6)3d for Ti XII transitions.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The luminescence properties of silica gels and silica gels doped with two rare earth complexes, Eu(TTA)(3) and Tb(o-CBA)(3) (TTA=thenoyltriffuocetate, o-CBA=o-chlorobenzoic acid) are reported and discussed. Pure silica gels show a blue luminescence, and the maximum excitation and emission wavelengths depend strongly on the solvents used. Both of the studied rare earth complexes exhibit the characteristic emissions of the rare earth ions in silica gels, i.e., Eu3+5D0-->F-7(J)(J=0,1,2,3,4), Tb3+5D4-->F-7(J)(J=3,4,5,6) transitions. Compared with the pure RE-complexes powder, the silica gels doped with RE-complexes show fewer emission lines of the rare earth ions. Furthermore the rare earth ion (Tb3+) presents a longer lifetime (1346 mu s) in silica gel doped with Tb(o-CBA)3 than in pure Tb((o-CBA)(3) powder (744 mu s). The reasons responsible for these results are discussed in the context.

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Neste trabalho, realizou-se a sntese do ceto-lcool pentaciclco ()-5, assim como o estudo de reatividade do grupo carbonila do mesmo frente a reaes de oximao e reduo. Realizou-se tambm a resoluo enantiomrica do composto ()-5 atravs de reao de transesterificao com acetato de vinila catalisada pela lipase da Candida rugosa. Altos excessos enantiomricos foram obtidos (>95%, RMN) tanto para o lcool (+)-5 quanto para o ster formado (-)-8. Sugere-se a existncia de uma interconverso enantiomrica no composto (+)-5, devido a observao de mistura racmica, quando o mesmo foi analisado por cromatografia gasosa em coluna quiral. Um mecanismo para tal interconverso, o qual envolve um rearranjo intramolecular, proposto.