Ligand Exchange Inducing Efficient Incorporation of CisPt Derivatives into Ureasil-PPO Hybrid and Their Interactions with the Multifunctional Hybrid Network

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrochemistry of organometallic compounds. Part IV. Oxidations of benzylic derivatives and p-substituted benzylic derivatives of bis(dimethylglyoximato) and bis(salicylaldehyde)o-phenylenediimine cobalt(III) in dimethylformamide

The electrochemical oxidation of some p-substituted benzylic derivatives of Co(III) dimethylglyoximato and Co(III)bis(salicylaldehydc)o-phenylenediimine in dimethylformamide. 0.2 M in tetraethyammonium perchlorate, on a platinum electrode, at several temperatures, is described as an ECE type, the first electrochemical step being a quasi-reversible one-electron charge transfer at room temperature. At temperatures around -20°C, or lower, the influence of the irreversible chemical decomposition of the oxidized species, via a solvent or other nucleophilic-assisted reaction, is negligible. It is suggested that at low temperatures the oxidation to the formally CoIV-R species is followed by an isomerization reaction in which this complex is partially transformed in a CoIII-(R) species or a s π-complex which undergoes an electroreduction at less positive potentials than those corresponding to the reduction of the CoIV-R species. © 1982.

Mercury(II) and thallium(III) organometallic derivatives of 2-Mercaptobenzoxazole

Some derivatives of 2-mercaptobenzoxazole (HL) of the type MRnL [M = Hg or Tl, R = Me or Ph and n = 1 (Hg) or 2 (Tl)] have been prepared. The structure of HgMeL has been determined by an X-ray diffraction study; in the crystal there are two independent planar molecules in each asymmetric unit, with the ligand in its thiolic form and an almost linear CHgS linkage. Weak intramolecular and intermolecular secondary interactions complement the mercurysulphur bond. The spectroscopic (IR, Raman, mass, 13C-NMR), conductimetric, and dipolar properties of this and the other compounds are discussed. © 1991.

Two Dibenzylbutyrolactol derivatives and other chemical constituents from Aristolochia peltato-deltoidea

Do extrato hexânico das partes aéreas de Aristolochia peltato-deltoidea Hoehne (Aristolochiaceae) foram isolados duas novas lignanas epiméricas do tipo dibenzilbutirolactol, rel-(8R, 8 S, 9S)-3,4-dimetoxi-3 ,4 -metilenodioxi-9b-etoxi- e rel-(8R, 8 S, 9R)-3,4-dimetoxi-3 ,4 -metilenodioxi-9a-etoxi-lignanas-8.8 ,9.O.9 , além da neolignana benzofurânica eupomatenóide-7, a-tocoferilquinona, b-sitosterol e estigmasterol. Do extrato clorofórmico foram isoladas duas lignanas dibenzilbutirolactonas diasteroisoméricas: rel-(8R, 8 R)- e rel-(8R, 8 S)-3,4-dimetoxi-3 ,4 -metilenodioxi-9-oxo-lignanas-8.8 ,9.O.9 . A composição química das frações apolares do extrato hexânico também foi analisada por CG/EM. Dentre os componentes detectados, dez foram identificados. As estruturas dos compostos isolados foram elucidadas utilizando-se métodos espectrométricos.

Geometrical coupling fields of a hypercomplex type

This paper presents an application of Laplace's equation obtained from a quaternionic function that satisfies the Cauchy-Riemann conditions determined earlier by Borges and Machado [#!BorgesZeMarcio!#]. Therefore, we show that it is possible to express in a single equation gravity, electric and magnetic potential fields, and this expression can only be provided due to a function that will be called here the coupling function.

Electrochemical behaviour of (N-R-4-cyanopyridinium)pentaammineruthenium(II) derivatives in acidic medium. Hydrolysis of coordinated nitriles

The electrochemical behaviour of N-R-4-cyanopyridinium (4-rcp) (R = methyl, decyl, dodecyl, or benzyl) coordinated to pentaammineruthenium(II) in CF3COOH-CF3COONa (μ = 0.1 M, pH 3) aqueous medium was studied by means of cyclic voltammetry and constant potential electrolysis. The electrochemical oxidation of the metallic centre (Ep ca 0.51 V/SCE) can be described as a reversible monoelectronic charge-transfer followed by an irreversible chemical reaction, which is the hydrolysis of N-R-4-cyanopyridiniumpentaammineruthenium(III) (A) to N-R-4-carboxamidepyridiniumruthenium (III) (B) with the kf1 values depending on the type of alkyl group. The E 1 2 values are not significantly influenced by the nature of the alkyl group. At more negative potential (ca -0.5 V/SCE), B undergoes an electrochemical reduction followed by an aquation reaction to produce aquopentaammineruthenium(II) and free N-R-4-carboxamidepyridinium. The amide was identified by comparison of its cyclic voltammogram and UV-vis spectrum with that of a sample prepared by chemical reaction. The results were also discussed by comparison with other systems, and show that nitrile-amide conversion catalysed by pentaammineruthenium(II) complexes is possible. © 1994.

Gas-phase reactivity of protonated 2-oxazoline derivatives: mass spectrometry and computational studies

RATIONALE: Oxazolines have attracted the attention of researchers worldwide due to their versatility as carboxylic acid protecting groups, chiral auxiliaries, and ligands for asymmetric catalysis. Electrospray ionization tandem mass spectrometric (ESI-MS/MS) analysis of five 2-oxazoline derivatives has been conducted, in order to understand the influence of the side chain on the gas-phase dissociation of these protonated compounds under collision-induced dissociation (CID) conditions. METHODS: Mass spectrometric analyses were conducted in a quadrupole time-of-flight (Q-TOF) spectrometer fitted with electrospray ionization source. Protonation sites have been proposed on the basis of the gas-phase basicity, proton affinity, atomic charges, and a molecular electrostatic potential map obtained on the basis of the quantum chemistry calculations at the B3LYP/6-31 + G(d, p) and G2(MP2) levels. RESULTS: Analysis of the atomic charges, gas-phase basicity and proton affinities values indicates that the nitrogen atom is a possible proton acceptor site. On the basis of these results, two main fragmentation processes have been suggested: one taking place via neutral elimination of the oxazoline moiety (99 u) and another occurring by sequential elimination of neutral fragments with 72 u and 27 u. These processes should lead to formation of R+. CONCLUSIONS: The ESI-MS/MS experiments have shown that the side chain could affect the dissociation mechanism of protonated 2-oxazoline derivatives. For the compound that exhibits a hydroxyl at the lateral chain, water loss has been suggested to happen through an E2-type elimination, in an exothermic step. Copyright (C) 2012 John Wiley & Sons, Ltd.

Host-guest interactions between xanthones and water: the role of O-H center dot center dot center dot O, C-H center dot center dot center dot O, and pi center dot center dot center dot pi contacts in the channel- and cage-type frameworks

In this article were studied two xanthone derivatives known as 1,5-dihydroxy-8-methoxyxanthone (I) and 1,3,7-trihydroxy-8-methoxyxanthone (II), which show one water molecule into their crystal structures. In xanthone I, there are water wires contributing to build up channel-like cavities along the c axis, whereas in xanthone II the water is surrounded by three xanthone molecules forming a cage-type structure. The geometries of I and II were optimized using the density functional theory method with B3LYP functional, and the results were compared with crystal structure. Both theoretical and experimental investigations reveal a concordance between structural parameters, with the xanthone core presenting an almost flat conformation and substituents adopting the more stable orientations. In the two compounds, the hydroxyl group linked at position 1 is involved in a resonance-assisted hydrogen bond with the carbonyl group. Besides, the supramolecular arrangement of the host/guest systems are stabilized mainly by classical intermolecular hydrogen bonds (O-H center dot center dot center dot O) involving xanthone-to-water and xanthone-to-xanthone. In addition, C-H center dot center dot center dot O weak hydrogen bonds, as well as pi-pi interactions play an important role to stabilize the crystal self-assembly of xanthones I and II. The results reported here underline the role of inclusion of water molecules and their different arrangement into the crystal structure of two xanthone host/guest systems.

The basic antioxidant structure for flavonoid derivatives

An antioxidant structure-activity study is carried out in this work with ten flavonoid compounds using quantum chemistry calculations with the functional of density theory method. According to the geometry obtained by using the B3LYP/6-31G(d) method, the HOMO, ionization potential, stabilization energies, and spin density distribution showed that the flavonol is the more antioxidant nucleus. The spin density contribution is determinant for the stability of the free radical. The number of resonance structures is related to the pi-type electron system. 3-hydroxyflavone is the basic antioxidant structure for the simplified flavonoids studied here. The electron abstraction is more favored in the molecules where ether group and 3-hydroxyl are present, nonetheless 2,3-double bond and carbonyl moiety are facultative.

Synthesis and characterization of a diruthenium(II,III)-ketoprofen compound and study of the in vitro effects on CRC cells in comparison to the naproxen and ibuprofen derivatives

A new diruthenium(II,III) complex, of formula [Ru2Cl(ket)(4)], Ruket, containing the non-steroidal anti-inflammatory drug ketoprofen was synthesized and mainly characterized by electrospray ionization mass spectrometry (ESI-MS), UV-Vis-IR electronic spectroscopy and FTIR and Raman vibrational spectroscopies. The four drug-carboxylato bridging ligands stabilize a Ru-2(II,III) mixed valent core in a paddlewheel type structure as confirmed by ESI mass spectra, electronic and vibrational spectroscopies and magnetic measurements. Ruket and the analogous compounds containing ibuprofen, Ruibp, and naproxen, Runpx, were tested for the biological effects in the human colon carcinoma cells HT-29 and Caco-2 expressing high and low levels of COX-2 respectively. All compounds only weakly affected the proliferation of the colorectal cancer cells HT-29 and Caco-2, and similarly only partially inhibited the production/activity of MMP-2 and MMP-9 by HT-29 cells, suggesting that COX-2 inhibition by these drugs can only partially be involved in the pharmacological effects of these derivatives. (c) 2012 Elsevier Ltd. All rights reserved.

A Facile, Versatile, and Mild Morita-Baylis-Hillman-Type Reaction for the Modular One-Pot Synthesis of Highly Functionalized MBH Adducts

MoritaBaylisHillman derivatives have been extensively investigated as intermediates in the preparation of important classes of compounds. However, there are intrinsic limitations regarding the structure of the Michael electrophile acceptors, the aldehydes, and the catalysts. Therefore, this transformation has several drawbacks, including, for example, its long reaction times. Herein we present a simple, general, fast, and high-yielding protocol for the one-pot synthesis of MoritaBaylisHillman derivatives. Our approach is driven by a lithium selenolate Michael/aldol operation with concomitant O-functionalization/selenoxide elimination cascade sequences.

Liquid crystalline oligofluorenes and their derivatives

Homo-oligofluorenes (OFn), polyfluorenes (PF2/6) and oligofluorenes with one fluorenenone group in the center (OFnK) were synthesized. They were used as model compounds to understand of the structure-property relationships of polyfluorenes and the origin of the green emission in the photoluminescence (after photooxidation of the PFs) and the electroluminescence (EL) spectra. The electronic, electrochemical properties, thermal behavior, supramolecular self-assembly, and photophysical properties of OFn, PF2/6 and OFnK were investigated. Oligofluorenes with 2-ethylhexyl side chain (OF2-OF7) from the dimer up to the heptamer were prepared by a series of stepwise transition metal mediated Suzuki and Yamamoto coupling reactions. Polyfluorene was synthesized by Yamamoto coupling of 2,7-dibromo-9,9-bis(2-ethylhexyl)fluorene. Oligofluorenes with one fluorenone group in the center (OF3K, OF5K, OF7K) were prepared by Suzuki coupling between the monoboronic fluorenyl monomer, dimer, trimer and 2, 7-dibromofluorenone. The electrochemical and electronic properties of homo-oligofluorenes (OFn) were systematically studied by several combined techniques such as cyclic voltammetry, differential pulse voltammetry, UV-vis absorption spectroscopy, steady and time-resolved fluorescence spectroscopy. It was found that the oligofluorenes behave like classical conjugated oligomers, i.e., with the increase of the chain-length, the corresponding oxidation potential, the absorption and emission maximum, ionization potential, electron affinity, band gap and the photoluminescence lifetime displayed a very good linear relation with the reciprocal number of the fluorene units (1/n). The extrapolation of these linear relations to infinite chain length predicted the electrochemical and electronic properties of the corresponding polyfluorenes. The thermal behavior, single-crystal structure and supramolecular packing, alignment properties, and molecular dynamics of the homo-oligofluorenes (OFn) up to the polymer were studied using techniques such as TGA, DSC, WAXS, POM and DS. The OFn from tetramer to heptamer show a smectic liquid crystalline phase with clearly defined isotropization temperature. The oligomers do show a glass transition which exhibits n-1 dependence and allows extrapolation to a hypothetical glass transition of the polymer at around 64 °C. A smectic packing and helix-like conformation for the oligofluorenes from tetramer to heptamer was supported by WAXS experiments, simulation, and single-crystal structure of some oligofluorene derivatives. Oligofluorenes were aligned more easily than the corresponding polymer, and the alignability increased with the molecular length from tetramer to heptamer. The molecular dynamics in a series of oligofluorenes up to the polymer was studied using dielectric spectroscopy. The photophysical properties of OFn and PF2/6 were investigated by the steady-state spectra (UV-vis absorption and fluorescence spectra) and time-resolved fluorescence spectra both in solution and thin film. The time-resolved fluorescence spectra of the oligofluorenes were measured by streak camera and gate detection technique. The lifetime of the oligofluorenes decreased with the extension of the chain-length. No green emission was observed in CW, prompt and delayed fluorescence for oligofluorenes in m-THF and film at RT and 77K. Phosphorescence was observed for oligofluorenes in frozen dilute m-THF solution at 77K and its lifetime increased with length of oligofluorenes. A linear relation was obtained for triplet energy and singlet energy as a function of the reciprocal degree of polymerization, and the singlet-triplet energy gap (S1-T1) was found to decrease with the increase of degree of polymerization. Oligofluorenes with one fluorenone unit at the center were used as model compounds to understand the origin of the low-energy (“green”) emission band in the photoluminescence and electroluminescence spectra of polyfluorenes. Their electrochemical properties were investigated by CV, and the ionization potential (Ip) and electron affinity (Ea) were calculated from the onset of oxidation and reduction of OFnK. The photophysical properties of OFnK were studied in dilute solution and thin film by steady-state spectra and time-resolved fluorescence spectra. A strong green emission accompanied with a weak blue emission were obtained in solution and only green emission was observed on film. The strong green emission of OFnK suggested that rapid energy transfer takes place from higher energy sites (fluorene segments) to lower energy sites (fluorenone unit) prior to the radiative decay of the excited species. The fluorescence spectra of OFnK also showed solvatochromism. Monoexponential decay behaviour was observed by time-resolved fluorescence measurements. In addition, the site-selective excitation and concentration dependence of the fluorescence spectra were investigated. The ratio of green and blue emission band intensities increases with the increase of the concentration. The observed strong concentration dependence of the green emission band in solution suggests that increased interchain interactions among the fluorenone-containing oligofluorene chain enhanced the emission from the fluorenone defects at higher concentration. On the other hand, the mono-exponential decay behaviour and power dependence were not influenced significantly by the concentration. We have ruled out the possibility that the green emission band originates from aggregates or excimer formation. Energy transfer was further investigated using a model system of a polyfluorene doped by OFnK. Förster-type energy transfer took place from PF2/6 to OFnK, and the energy transfer efficiency increased with increasing of the concentration of OFnK. Efficient funneling of excitation energy from the high-energy fluorene segments to the low-energy fluorenone defects results from energy migration by hopping of excitations along a single polymer chain until they are trapped on the fluorenone defects on that chain or transferred onto neighbouring chains by Förster-type interchain energy transfer process. These results imply that the red-shifted emission in polyfluorenes can originate from (usually undesirable) keto groups at the bridging carbon atoms-especially if the samples have been subject to photo- or electro-oxidation or if fluorenone units are present due to an improper purification of the monomers prior to polymerization.

Black-scholes type equations

In this work we are concerned with the analysis and numerical solution of Black-Scholes type equations arising in the modeling of incomplete financial markets and an inverse problem of determining the local volatility function in a generalized Black-Scholes model from observed option prices. In the first chapter a fully nonlinear Black-Scholes equation which models transaction costs arising in option pricing is discretized by a new high order compact scheme. The compact scheme is proved to be unconditionally stable and non-oscillatory and is very efficient compared to classical schemes. Moreover, it is shown that the finite difference solution converges locally uniformly to the unique viscosity solution of the continuous equation. In the next chapter we turn to the calibration problem of computing local volatility functions from market data in a generalized Black-Scholes setting. We follow an optimal control approach in a Lagrangian framework. We show the existence of a global solution and study first- and second-order optimality conditions. Furthermore, we propose an algorithm that is based on a globalized sequential quadratic programming method and a primal-dual active set strategy, and present numerical results. In the last chapter we consider a quasilinear parabolic equation with quadratic gradient terms, which arises in the modeling of an optimal portfolio in incomplete markets. The existence of weak solutions is shown by considering a sequence of approximate solutions. The main difficulty of the proof is to infer the strong convergence of the sequence. Furthermore, we prove the uniqueness of weak solutions under a smallness condition on the derivatives of the covariance matrices with respect to the solution, but without additional regularity assumptions on the solution. The results are illustrated by a numerical example.

Development of Organocatalytic stereoselective SN1 type reactions

The proposal in my thesis has been the study of Stereoselective α-alkylation through SN1 type reaction. SN1 type reaction involves a stabilized and reactive carbocation intermediate By taking advantages of stability of particular carbocations, the use of carbocations in selective reactions has been important. In this work has been necessary to know the stability and reactivity of carbocations. And the work of Mayr group has helped to rationalize the behaviour and reactivity between the carbocations and nucleophiles by the use of Mayr’s scale of reactivity. The use of alcohols to performed the stable and reactive carbocations have been the key in my thesis. The direct nucleophilic substitution of alcohols has been a crucial scope in the field of organic synthesis, because offer a wide range of intermediates for the synthesis of natural products and pharmaceutics synthesis. In particular the catalytic nucleophilic direct substitution of alcohols represents a novel methodology for the preparation of a variety of derivatives, and water only as the sub-product in the reaction. The stereochemical control of the transformation C-H bond into stereogenic C-C bond adjacent to carbonyl functionalized has been studied for asymmetric catalysis. And the field of organocatalysis has introduced the use of small organic molecule as catalyst for stereoselective transformations. Merging these two concepts Organocatalysis and Mayr’s scale, my thesis has developed a new approach for the α-alkylation of aldehydes and ketones through SN1 type reaction.

Activity and mechanisms of action of novel organosulfur derivatives of the HDAC inhibitor Valproic Acid in human experimental models of non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) represents the leading cause of cancer death worldwide, and 5-year survival is about 16% for patients diagnosed with advanced lung cancer and about 70-90% when the disease is diagnosed and treated at earlier stages. Treatment of NSCLC is changed in the last years with the introduction of targeted agents, such as gefitinib and erlotinib, that have dramatically changed the natural history of NSCLC patients carrying specific mutations in the EGFR gene, or crizotinib, for patients with the EML4-ALK translocation. However, such patients represent only about 15-20% of all NSCLC patients, and for the remaining individuals conventional chemotherapy represents the standard choice yet, but response rate to thise type of treatment is only about 20%. Development of new drugs and new therapeutic approaches are so needed to improve patients outcome. In this project we aimed to analyse the antitumoral activity of two compounds with the ability to inhibit histone deacethylases (ACS 2 and ACS 33), derived from Valproic Acid and conjugated with H2S, in human cancer cell lines derived from NSCLC tissues. We showed that ACS 2 represents the more promising agent. It showed strong antitumoral and pro-apoptotic activities, by inducing membrane depolarization, cytocrome-c release and caspase 3 and 9 activation. It was able to reduce the invasive capacity of cells, through inhibition of metalloproteinases expression, and to induce a reduced chromatin condensation. This last characteristic is probably responsible for the observed high synergistic activity in combination with cisplatin. In conclusion our results highlight the potential role of the ACS 2 compound as new therapeutic option for NSCLC patients, especially in combination with cisplatin. If validated in in vivo models, this compound should be worthy for phase I clinical trials.