New insights on surface-enhanced Raman scattering based on controlled aggregation and spectroscopic studies, DFT calculations and symmetry analysis for 3,6-bi-2-pyridyl-1,2,4,5-tetrazine adsorbed onto citrate-stabilized gold nanoparticles

Asystematic study on the surface-enhanced Raman scattering (SERS) for 3,6-bi-2-pyridyl-1,2,4,5-tetrazine (bptz) adsorbed onto citrate-modified gold nanoparticles (cit-AuNps) was carried out based on electronic and vibrational spectroscopy and density functional methods. The citrate/bptz exchange was carefully controlled by the stepwise addition of bptz to the cit-AuNps, inducing flocculation and leading to the rise of a characteristic plasmon coupling band in the visible region. Such stepwise procedure led to a uniform decrease of the citrate SERS signals and to the rise of characteristic peaks of bptz, consistent with surface binding via the N heterocyclic atoms. In contrast, single addition of a large amount of bptz promoted complete aggregation of the nanoparticles, leading to a strong enhancement of the SERS signals. In this case, from the distinct Raman profiles involved, the formation of a new SERS environment became apparent, conjugating the influence of the local hot spots and charge-transfer (CT) effects. The most strongly enhanced vibrations belong to a(1) and b(2) representations, and were interpreted in terms of the electromagnetic and the CT mechanisms: the latter involving significant contribution of vibronic coupling in the system. Copyright (C) 2010 John Wiley & Sons, Ltd.

Synthesis, spectral studies and X-ray crystal structure of N,N `-(+/-)-trans-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) H-2(t-3-EtOsalchxn)

The synthesis, spectra and X-ray crystal structure of N,N`-(+/-)-trans-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) H-2(t-3-EtOsalchxn), a salen-type ligand, are reported. The Schiff base was characterized by elemental analysis, m.p., IR, electronic spectra, H-1 and C-13 NMR spectra. The spectra are discussed and compared with those of N,N`-(+/-)-trans-1,2-cyclohexylenebis(salicylideneamine), H-2(t-salchxn). The electronic and IR spectra were also resolved by deconvolution. The influence of the ethoxy group on the IR, electronic spectrum, H-1 and C-13 NMR spectra is discussed. Strong intramolecular forces are present as supported by the IR and H-1 NMR spectra and the X-ray crystal structure. An intermolecular hydrogen bond is observed and appears twice in a pair of molecules in the unit cell. (c) 2007 Elsevier B.V. All rights reserved.

Estudo de reatividade e resolução enantiomérica do (+-)-10-exo-hidróxipentaciclo[6.2.1.1 3,6.0 2,7. 0 5.9] dodecan-4-ona

Neste trabalho, realizou-se a síntese do ceto-álcool pentaciclíco (±)-5, assim como o estudo de reatividade do grupo carbonila do mesmo frente a reações de oximação e redução. Realizou-se também a resolução enantiomérica do composto (±)-5 através de reação de transesterificação com acetato de vinila catalisada pela lipase da Candida rugosa. Altos excessos enantioméricos foram obtidos (>95%, RMN) tanto para o álcool (+)-5 quanto para o éster formado (-)-8. Sugere-se a existência de uma interconversão enantiomérica no composto (+)-5, devido a observação de mistura racêmica, quando o mesmo foi analisado por cromatografia gasosa em coluna quiral. Um mecanismo para tal interconversão, o qual envolve um rearranjo intramolecular, é proposto.

Níveis de julgamento de alunos de 1., 2. e 3. graus de ensino

Os níveis de julgamen to dos alunos de 1 2 , 22 e ,:3 2 graus de ensino da Rede de E'sco las Particulares e da ~~ndação Universitária da cidade de Lages - Santa Catari ~a -, é um estudo teórico e de investigação prática, que -pretende verificar e discutir as relações entre a quali~ . dade ou maturidade de julgamento .. ' . e as var~ave~s idade grau de escolaridade, capacidade intelectual e nível só- --ci.o-econômico dos alunos ,sujeitos da pesquisa. A amostra foi sorteada aleatoriamente entre to- dos os alunos da 8! série do 12 grau, 2~' série do 29 grau e 3! série do 3 2 grau, num percentual aproximado de 20% da população total visada. Constituiu-se, assim, uma amos tra de 152 sujeitos, extTa{da de uma população de 898 a~ . . lunos. Os objetivos específicos que orientaram o estu- , ." ... . .' ,.., . do resumem-se na anal~se e discussao das relaçoes entreo nível de julgamento e as demais variáveis, isto é, ida~ de, grau de escolaridade, capacidade intelectual e nível sócio-econômico dos ,alunos pesquisados. Os resultados indicam que: 1) a maioria absolu- , ta dos sujeitos tanto de 12 e 22 graus qcinnto os de .j2 grau não alcançou'os níveis de julgamento mais maduros - ou seja - julgamento imaginativo-explicativo e imaginati vo-explicati vo-compreensi vo.· .2) Os sujei tos revelam -a- centuada dificuldade de raciocínio e julgamento' em ,rela ção ao texto-teste de estrutura lógica. 3) As variáveis' ~dade, grau de escolaridade, nível 56cio~ecortômico rela- ',c~onam-se,. em geral, positivamente com o nível de julga- ~mento, embora, no caso desta pesquisa, essa relação seja :fraca, possivelmente em função da pou.ca dispersão ougra!! de homog'eneic.ade' dos escores obtidos pelos sujeitos. Es- -sa homogeneidade de resultados levanta problemas que me- receriam novos estudos para maiores esclarecimentos sobre as condiç;es de desenvolvimento do processo de julga- mento, sejam internas ou externas à escola. são levantadas questões relativas, principalmen- te, à ação da escola, aos livros textos nela utilizados às condições precárias dos professores, à concepção tradi ciônal de educação e sobre o sistema ou contexto social a tual dentro do qual a escola é um sub-sistema. são sugeridas, no final do trabalho, pesquisas e estudos que visem amplioar o c onhecimento a raspei to do d~ senvolvimento do processo de julgar, bem como, pesquisas que procurem relacionar o nível sócio-econômico do profes sor e a quantidade e qualidade de leituras feitas por ele com o desempenho dos alunos.

1-Benzoyl-5-phenyl-2-(propan-2-yl)-1,2,3,4-tetrahydropyrimidin-4-one

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of metal ions in natural waters by flame-AAS after preconcentration on a 5-amino-1,3,4-thiadiazole-2-thiol modified silica gel.

5-amino-1,3,4-thiadiazole-2-thiol groups attached on a silica gel surface have been used for adsorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II) and Zn(II) from aqueous solutions. The adsorption capacities for each metal ion were (in mmol.g(-1)): Cd(II)= 0.35, Co(II)= 0.10, Cu(II)= 0.15, Fe(III)= 0.20, Hg(Il)= 0.46, Ni(II)= 0.16, Pb(II)= 0.13 and Zn(II)= 0.15. The modified silica gel was applied in the preconcentration and quantification of trace level metal ions present in water samples (river, and bog water).

On the search for potential anti-Trypanosoma cruzi drugs: Synthesis and biological evaluation of 2-hydroxy-3-methylamino and 1,2,3-triazolic naphthoquinoidal compounds obtained by click chemistry reactions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Interaction of amphiphilic derivatives of chitosan with DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Superstrings in graviphoton background and N=1/2+3/2 supersymmetry

Motivated by Ooguri and Vafa, we study superstrings in flat R-4 in a constant self-dual graviphoton background. The supergravity equations of motion are satisfied in this background which deforms the N = 2 d = 4 flat space super-Poincare algebra to another algebra with eight supercharges. A D-brane in this space preserves a quarter of the supercharges; i.e. N = 1/2 supersymmetry is realized linearly, and the remaining N = 3/2 supersymmetry is realized nonlinearly. The theory on the brane can be described as a theory in noncommutative superspace in which the chiral fermionic coordinates theta(alpha) of N = 1 d = 4 superspace are not Grassman variables but satisfy a Clifford algebra.

Search for W H associated production in 5.3 fb(-1) of p(p)over-bar collisions at the Fermilab Tevatron

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for associated production of charginos and neutralinos in the trilepton final state using 2.3 fb(-1) of data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for Diphoton Events with Large Missing Transverse Energy in 6.3 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

1,3-dipolar cycloaddition of CS2 to the coordinated azide in the cyclopalladated [Pd(bzan)(mu-N-3)](2). Crystal and molecular structure of di(mu-N,S-1,2,3,4-thiatriazole-5-thiolate)bis[(benzylideneaniline-C-2,N)palladium(II)]

The compound [Pd(bzan)(mu -N-3)](2) 1, bzan = benzylideneaniline, was prepared from [Pd(bzan) (mu -OOCCH3)](2) by an anion exchange reaction. The 1,3-dipolar cycloaddition of carbon disulfide to the bridged coordinated azide in the cyclometallated compound I was investigated. The species resulting from this reaction, di(mu -N,S-1,2,3,4-thiatriazol-5-thiolate)bis[(benzylideneaniline)palladium(II)] 2, was characterized by IR spectroscopy and X-ray diffraction. The compound 2 is a dimer containing two [Pd(benzylideneaniline)] moieties connected by two vicinal bridging N,S-1,2,3,4-thiatriazole-5-thiolate anions in a square-planar coordination geometry for the palladium atoms.

Revisiting the addition reaction of TeCl4 to alkynes: the crystal structure and docking studies of 1-chloro-2-trichlorotelluro-3-phenyl-propen-2-ol

Tellurium tetrachloride adds to alkynes via two pathways: a concerted syn addition, that yields Z-tri- and tetra-substituted alkenes or by an anti addition that yields E-alkenes. The mechanistic aspects of these divergent pathways have been reevaluated at the light of crystallographic data. The molecules, of the title compound, in the crystal, are associated in a helical fashion with a Te...Te pitch of 6.3492(6) angstrom. As it exhibits inhibitory activity for cathepsin B and in order to gain more insight of the inhibition mechanism, a docking study was undertaken providing insight on why organic telluranes are more efficient inhibitors than inorganic ones as AS-101. (c) 2006 Elsevier B.V. All rights reserved.