Papers by Eduardo R Triboni
Journal of Luminescence, 2006
Interface - Comunicação, Saúde, Educação, 1998
... 1998. doi: 10.1590/S1414-32831998000200019. CRIAÇÃO. Eduardo Triboni. UM VíRUS ME DISSE. ... ... more ... 1998. doi: 10.1590/S1414-32831998000200019. CRIAÇÃO. Eduardo Triboni. UM VíRUS ME DISSE. ... Darwin, perfeito. Mais lindo, porém, é a DNA polimerase trabalhando pela vida. EduardoTriboni é estudante de Química da Universidade de São Paulo, USP, São Carlos. ...
Materials Chemistry and Physics, 2015
1 of 25 Thursday , April 07, 2005 Elsevier R e v i e w C o p y 2 4-Methoxy-N-methyl-1,8-naphthali... more 1 of 25 Thursday , April 07, 2005 Elsevier R e v i e w C o p y 2 4-Methoxy-N-methyl-1,8-naphthalimide presents considerable solvatochromism and its spectral properties have been studied in several polar/non polar and protic/aprotic solvents, as well as in ethanol/water mixtures. The results have revealed a strong influence of the solvent polarity and its hydrogen-bond donor capability on this compound photophysical properties. Preferential solvation models describe the shifts in the probe absorption well, but they fail to describe the shifts of emission maxima. Pseudo-linear approximations between composition and transition energies, E T , could be used to study the composition of ethanol/water mixtures, simplifying the mathematical treatment for eventual analytical applications. KEYWORDS: Naphthalimide, solvatochromism and spectrophotometric probe, ethanol/water mixtures.
Journal of Luminescence, 2014
Excited state proton transfer processes in vitreous glasses and in solid mixtures are investigate... more Excited state proton transfer processes in vitreous glasses and in solid mixtures are investigated by steady state fluorimetry and laser flash photolysis kinetic studies with the photoacids pyranine and 2-naphthol. Glasses were derived from TEOS by the sol-gel condensation process and hydrated solid mixtures from NaCl or KH 2 PO 4 /K 2 HPO 4 crystals. The extent of the water content necessary for the reaction is determined. Shrinkage of TEOS derived monoliths from water loss leads to an increase in proton transfer extent due to the increase in local concentrations of accepting and donor buffer species, but the concomitant increase in the ionic strength actuates in an opposite direction. Furthermore, water losses by aging of air-exposed gel goes to a critical 20% weight fraction, beyond it proton transfer reactions are hindered. Similar studies with solid NaCl or solid phosphate buffer mixtures demonstrated the same critical water level indicating that free water molecules are crucial for the proton to escape from the original cage where the geminate ion pair [-||RO À n H þ ||-] is formed and can undergo coupled proton transfer reactions.
Journal of Chemical Research-s, 2004
ChemInform, 2006
Carboxylic acid derivatives Q 0950 Synthesis of 4-Alkoxy-N-substituted-1,8-naphthalimides. -Impro... more Carboxylic acid derivatives Q 0950 Synthesis of 4-Alkoxy-N-substituted-1,8-naphthalimides. -Improved approaches to compounds (III) (6 examples) are developed. They involve reaction of 4-nitro--N-alkyl-1,8-naphthalimides with alkoxides, generated in situ, under stirring at room temperature (silent mode) or sonochemical conditions. -(TRIBONI, E. R.; BERLINCK, R. G. S.; POLITI, M. J.; BERCI*, P. F.; J.
Materials Research, 2010
The reaction of Naphthalene 1,4,5,8-dianhydride (NTCDA) with elemental aluminum(0) powder is stud... more The reaction of Naphthalene 1,4,5,8-dianhydride (NTCDA) with elemental aluminum(0) powder is studied in an aqueous alcoholic KOH mixture to search for the NTCDA anion and dianion electron-adducts. After analyzing various reaction conditions it was found that the reaction yielded a greenish precipitate in 3:1 (v:v) ethanol:water mixture. This powder is composed mainly of aluminum trihydroxide crystallites of bayerite [a-Al(OH 3 ) (s) ] and the organic content is approximately 6%. This hybrid material proved to be paramagnetic even after exposure to air for one year and at temperatures up to 200 °C. Typical carbonylic bound to metal IR bands and reflectance UV-VIS spectra demonstrate the entrapment of NTCDA radical anion into the aluminum trihydroxide, hence rendering its green color and a paramagnetic behavior. Thus, besides the understanding of an aluminum reaction in suspension, the entrapment of an organic material (NTCDA) that stays stable as the corresponding radical can provide an interesting option for the synthesis of aluminum trihydroxide composites.
Journal of Physical Organic Chemistry, 2009
The second-order rate constants of thiolysis by n-heptanethiol on 4-nitro-N-n-butyl-1,8-naphthali... more The second-order rate constants of thiolysis by n-heptanethiol on 4-nitro-N-n-butyl-1,8-naphthalimide (4NBN) are strongly affected by the water-methanol binary mixture composition reaching its maximum at around 50% mole fraction. In parallel solvent effects on 4NBN absorption molar extinction coefficient also shows a maximum at this composition region. From the spectroscopic study of reactant and product and the known H-bond capacity of the mixture a rationalization that involves specific solvent H-donor interaction with the nitro group is proposed to explain the kinetic data. Present findings also show a convenient methodology to obtain strongly fluorescent imides, valuable for peptide and analogs labeling as well as for thio-naphthalimide derivatives preparations.
Journal of Physical Organic Chemistry, 2003
Nitronaphthalimides are a particularly interesting group of nitroaromatics used for staining cell... more Nitronaphthalimides are a particularly interesting group of nitroaromatics used for staining cells in hypoxia and in photodynamic therapy. The kinetics of the aromatic nucleophilic substitution of the nitro-group of 4-nitro-N-n-butyl-1,8-naphthalimide (4-NBN) by n-heptanethiol (RSH), thiophenol (ArSH) and 2-hydroxy-1ethanethiol (HESH) in aqueous solutions containing micelles and in water-methanol mixtures were analyzed. The substitution of the nitro group by aromatic or aliphatic thiols led to fluorescent substitution products. Hexadecyltrimethylammonium chloride micelles (CTAC) increased the rate of thiolysis of 4-NBN by 1 Â 10 5 (RSH) and 4 Â 10 5 (ArSH) fold. For the reaction of ArSH with 4-NBN the calculated second-order rate constant in the micellar phase, k 2m , is 1.4 times higher than that in the aqueous phase, k 2w . For the reaction of ArSH with 4-NBN, k 2m /k 2w = 0.05. Both k 2w and k 2m decreased with increasing pK a of the thiol, suggesting that thiolate attack is not rate limiting in either the aqueous phase or micellar pseudophase. The high micellar rate acceleration is therefore largely due to concentration of the reagents in the micellar phase and effects on the thiol acid-base equilibrium. a The following values were used in both fitting procedures: a = 0.27; CMC = 5.5 Â 10 À4 M; K OH/Cl = 0.13; 25 K Cl/Br = 0.615; 25 K NBN = 1.877 M À1 ; V = 0.32 l mol À1 ; pK w = 13.833 at 30°C. 22
Journal of Photochemistry and Photobiology A: Chemistry, 2008
Photochemical and photophysical properties of 1-(2-quinolyl)-2-naphthol (2QN) in water and organi... more Photochemical and photophysical properties of 1-(2-quinolyl)-2-naphthol (2QN) in water and organic solvents, as well in glassy media were studied to investigate the occurrence of intramolecular excited state prototropic reactions between the naphthol and quinoline rings. Spectral data show the two chromophores apparently behaving independently. However, in acid aqueous media or in low polarity solvents a new electronic transition red shifted band with respect to that of the parent compounds assigned to an intramolecular H-bond and to a quinoid form, respectively, shows up. Model calculations and R-X data lend support to a minimum energy conformer having a dihedral angle of ∼ 39 • between the two groups. Singlet excited state properties (S 1 ) show a high suppressive effect of one ring over the other, resulting in very low emission yields at room temperature. The occurrence of excited state intramolecular proton transfer is observed in water (zwitter ion form) and in low polarity media (quinoid form) and originates from a previously CT H-bonded state. Phosphorescence data allowed a reasonable description of the electronic states of 2QN. In addition two new derivatives were prepared having the N atom blocked by methylation and both the N and O groups blocked by a CH 2 bridge. The spectral data of these two compounds confirmed the attributions made for 2QN.
Journal of Photochemistry and Photobiology A: Chemistry, 2009
Three novel hybrid organic/inorganic materials were synthesized from 4-substituted (NO2, Br, H) 1... more Three novel hybrid organic/inorganic materials were synthesized from 4-substituted (NO2, Br, H) 1,8-naphthalene imide-N-propyltriethoxysilane by the sol–gel process. These materials were obtained as a xerogel and partially characterized. The ability to photosensitize the oxidation and degradation of tryptophan indole ring by these materials was studied through photophysical and photochemical techniques. Although the derivatives containing Br and NO2 as substituent do not cause efficient tryptophan photodamage, the hybrid material obtained from 1,8-naphthalic anhydride is very efficient to promote tryptophan photooxidation. By using laser flash photolysis it was possible to verify the presence of naphthalene imide transient radical species. The presence of oxygen causes an increase of the yield of radical formation. These results suggest that the mechanism of photodegradation of tryptophan occurs by type I, i.e. the transient radical (TrpH+) formed by the direct reaction of the triplet state of the naphthalene imide moiety with tryptophan. Thus a inorganic–organic hybrid material that can be used to promote the oxidation of biomolecules was obtained.
Journal of Luminescence, 2006
The photophysical properties of N-methyl-1,8-naphthalimide (NI) and 4-phenoxy-N-methyl-1,8-naphth... more The photophysical properties of N-methyl-1,8-naphthalimide (NI) and 4-phenoxy-N-methyl-1,8-naphthalimide (4-PNI) are studied by steadystate and time-resolved emission measurements. Both absorption and fluorescence spectra are red-shifted when the electron donor phenoxy group (-OPh) is introduced at the C-4 position. Compared to NI, the spectral shift in acetonitrile is 27 and 42 nm for the absorption and fluorescence, respectively. The 4-PNI shows high fluorescence emission in non-polar aprotic solvents that can be ascribed to stabilization of the S 1 state. The emission intensity of the 4-PNI decreases by addition of water to dioxane solution, and the fluorescence quenching occurs by combination of dynamic and static contribution ascribed to specific solute-solvent interaction.
Bioconjugate Chemistry, 2009
Fluorescent proteins from the green fluorescent protein family strongly interact with CdSe/ZnS an... more Fluorescent proteins from the green fluorescent protein family strongly interact with CdSe/ZnS and ZnSe/ZnS nanocrystals at neutral pH. Green emitting CdSe/ZnS nanocrystals and red emitting fluorescent protein dTomato constitute a 72% efficiency FRET system with the largest alteration of the overall photoluminescence profile, following complex formation, observed so far. The substitution of ZnSe/ZnS for CdSe/ZnS nanocrystals as energy donors enabled the use of a green fluorescent protein, GFP5, as energy acceptor. Violet emitting ZnSe/ZnS nanocrystals and green GFP5 constitute a system with 43% FRET efficiency and an unusually strong sensitized emission. ZnSe/ZnS-GFP5 provides a cadmium-free, high-contrast FRET system that covers only the high-energy part of the visible spectrum, leaving room for simultaneous use of the yellow and red color channels. Anisotropic fluorescence measurements confirmed the depolarization of GFP5 sensitized emission.
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Papers by Eduardo R Triboni