Fabiane Trindade | Universidade de São Paulo (original) (raw)

Papers by Fabiane Trindade

Ceramics International, 2021

Journal of Photochemistry and Photobiology A: Chemistry, 2017

Mesoporous organosilicas containing covalently bound 1,8-naphthalimides (NI) were shown to be eff... more Mesoporous organosilicas containing covalently bound 1,8-naphthalimides (NI) were shown to be efficient heterogeneous catalysts for the photodegradation of methylene blue (MB), a typical textile pollutant. The NI-containing mesoporous silicas (SBANI materials) were prepared by a co-condensation reaction, in conditions similar to those used for inorganic SBA-15. For the photocatalytic tests, the SBANI materials were suspended in aqueous MB solutions, and the suspensions were irradiated with a 100 W Hg lamp (bandpass filter: 320-480 nm). The activity of the SBANI catalysts was proportional to the NI content in the sample. When MB was irradiated in the presence of a sample with high NI content, total bleaching of MB was observed after 300 min irradiation. In addition, blue shifts in the visible MB band were observed during irradiation. The results can be explained by concomitant mineralization and Ndemethylation of MB. N-demethylation led to the formation of azure dyes, which were detected in the reaction mixtures after irradiation. The photocatalytic activity can be attributed to the formation of NI triplets, which can react with MB by both Type (II) (via oxygen reactive species) and Type I (via electron transfer) mechanisms. 2016 Elsevier B.V. All rights reserved.

Chemistry (Weinheim an der Bergstrasse, Germany), Jan 26, 2015

Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO-Au... more Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO-Au NPs) were obtained by the in situ reduction of GO and AuCl4 (-) (aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O2 through the transfer of SPR-excited hot electrons to O2 molecules adsorbed from air. The SPR-mediated catalytic oxidation of p-aminothiophenol (PATP) to p,p'-dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR-mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge-transfer processes from rGO to Au took place and contributed to improved SPR-mediated activity. Since the transfer of electrons from Au to adsorbed O2 molecules is the crucial step for PATP oxidation, in addition to the SPR-excited hot electrons o...

Nano Design for Smart Gels, 2019

Abstract This chapter will address the fundamental aspects, preparation, and feasibility of scale... more Abstract This chapter will address the fundamental aspects, preparation, and feasibility of scale of the different systems that are made by the chemical sol–gel process. Examples of the various types of materials that are constructed by this route will be illustrated. These materials include ordered mesoporous sol–gel materials, such as sol–gel silica materials, organic–inorganic hybrid mesoporous silicas, and functionalization of periodic mesoporous silica materials postsynthetic grafting, and the synthesis of organo-periodic mesoporous silicas.

ACS Applied Nano Materials

Fuel Processing Technology

The Journal of Physical Chemistry C, 2015

Angewandte Chemie International Edition, 2015

By a combination of theoretical and experimental design, we probed the effect of a quasi-single e... more By a combination of theoretical and experimental design, we probed the effect of a quasi-single electron on the surface plasmon resonance (SPR)-mediated catalytic activities of Ag nanoparticles. Specifically, we started by theoretically investigating how the E-field distribution around the surface of a Ag nanosphere was influenced by static electric field induced by one, two, or three extra fixed electrons embedded in graphene oxide (GO) next to the Ag nanosphere. We found that the presence of the extra electron(s) changed the E-field distributions and led to higher electric field intensities. Then, we experimentally observed that a quasi-single electron trapped at the interface between GO and Ag NPs in Ag NPs supported on graphene oxide (GO-Ag NPs) led to higher catalytic activities as compared to Ag and GO-Ag NPs without electrons trapped at the interface, representing the first observation of catalytic enhancement promoted by a quasisingle electron.

Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au... more Hybrid materials in which reduced graphene oxide (rGO) is decorated with Au nanoparticles (rGO–Au NPs) were obtained by the in situ reduction of GO and AuCl4−(aq) by ascorbic acid. On laser excitation, rGO could be oxidized as a result of the surface plasmon resonance (SPR) excitation in the Au NPs, which generates activated O2 through the transfer of SPR-excited hot electrons to O2 molecules adsorbed from air. The SPR-mediated catalytic oxidation of p-aminothiophenol (PATP) to p,p′-dimercaptoazobenzene (DMAB) was then employed as a model reaction to probe the effect of rGO as a support for Au NPs on their SPR-mediated catalytic activities. The increased conversion of PATP to DMAB relative to individual Au NPs indicated that charge-transfer processes from rGO to Au took place and contributed to improved SPR-mediated activity. Since the transfer of electrons from Au to adsorbed O2 molecules is the crucial step for PATP oxidation, in addition to the SPR-excited hot electrons of Au NPs, the transfer of electrons from rGO to Au contributed to increasing the electron density of Au above the Fermi level and thus the Au-to-O2 charge-transfer process.

Dyes and Pigments, 2011

This work describes the covalent grafting of 4-amino-1,8-naphthalimides, which are fluorescent dy... more This work describes the covalent grafting of 4-amino-1,8-naphthalimides, which are fluorescent dyes with very interesting optical properties, onto the walls of mesoporous molecular sieves. The mesoporous materials MCM-41 and SBA-15 were first treated with 3-aminopropyltriethoxysilane, generating amine-rich surfaces that were further reacted with 4-amino-1,8-naphthalic anhydride, resulting in yellow fluorescent solids. The success of the modification reactions was confirmed by elemental analysis, X-ray diffraction patterns, infrared spectroscopy, scanning electron microscopy and UV/visible and fluorescence spectroscopy. The emission spectra of the dye bound to MCM-41 was quite insensitive to solvent polarity, in contrast to dye-grafted SBA-15, which showed a high solvent sensitivity. These results suggest a tight fit of the dye molecules within the channels of MCM-41, leaving no room for the solvent molecules. In the case of SBA-15, the large pore size allows the invasion of the channels by solvent molecules, resulting in solvation of the encaged chromophore.

Microporous and …, Dec 23, 2007

This work describes the covalent grafting of 3,4,9,10-perylenediimides (PDI), which are fluoresce... more This work describes the covalent grafting of 3,4,9,10-perylenediimides (PDI), which are fluorescent dyes with very interesting optical properties, onto the walls of mesoporous molecular sieves MCM-41 and SBA-15. The mesoporous materials were first treated with 3-aminopropyltriethoxysilane (APTES) in anhydrous toluene, generating amine-containing surfaces. The amine-containing materials were then reacted with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCA), generating surface-grafted PDI. Infrared spectra of the materials showed that the reaction with amino groups took place at both anhydride ends of the PTCA molecule, resulting in surface attached diimides. No sign of unreacted anhydride groups were found. The new materials, designated as MCMN2PDI and SBAN2PDI, presented absorption and emission spectra corresponding to weakly coupled PDI chromophores, in contrast to the strongly coupled rings usually found in solid PDI samples. The materials showed a red fluorescence, which could be observed by the naked eye under UV irradiation or with a fluorescence microscope. The PDI-modified mesoporous materials showed electrical conductivity when pressed into a pellet. The results presented here show that the new materials are potentially useful in the design of nanowires.

RSC Advances, May 22, 2012

In the present paper, we report on the molecular interaction and photochemistry of TiO2 nanoparti... more In the present paper, we report on the molecular interaction and photochemistry of TiO2 nanoparticles (NPs) and cytochrome c systems for understanding the effects of supramolecular organization and electron transfer by using two TiO2 structures: P25 TiO2 NPs and titanate nanotubes. The adsorption and reduction of cytochrome c heme iron promoted by photo-excited TiO2, arranged as P25 TiO2 NPs and as nanotubes, were characterized using electronic absorption spectroscopy, thermogravimetric analysis, and atomic force microscopy. In an aqueous buffered suspension (pH 8.0), the mass of cytochrome c adsorbed on the P25 TiO2 NP surface was 2.3 fold lower (0.75 μg m−2) than that adsorbed on the titanate nanotubes (1.75 μg m−2). Probably due to the high coverage of titanate nanotubes by adsorbed cytochrome c, the low amount of soluble remaining protein was not as efficiently photo-reduced by this nanostructure as it was by the P25 TiO2 NPs. Cytochrome c, which desorbed from both titanium materials, did not exhibit changes in its redox properties. In the presence of the TiO2 NPs, the photo-induced electron transfer from water to soluble cytochrome c heme iron was corroborated by the following findings: (i) identification by EPR of the hydroxyl radical production during the irradiation of an aqueous suspension of TiO2 NPs, (ii) impairment of a cytochrome c reduction by photo-excited TiO2 in the presence of dioxane, which affects the dielectric constant of the water, and (iii) change in the rate of TiO2-promoted cytochrome c reduction when water was replaced with D2O. The TiO2-promoted photo-reduction of cytochrome c was reverted by peroxides. Cytochrome c incorporated in the titanate nanotubes was also reversibly reduced under irradiation, as confirmed by EPR and UV-visible spectroscopy.

Journal of Nanoscience and Nanotechnology, Oct 10, 2007

The encapsulation of microperoxidases (MPs) into molecular sieves with controlled pore size, such... more The encapsulation of microperoxidases (MPs) into molecular sieves with controlled pore size, such as the mesoporous silica MCM-41, represents a nanotechnology strategy to control the catalytic properties of MPs and mimic the enzymatic activity of hemoproteins. In this work, the ferric microperoxidase-11 (MP-11), obtained from trypsin-catalyzed hydrolysis of horse-heart cytochrome c, was entrapped in MCM-41, thus resulting in a catalyst (Fe(III)MP11MCM41) with catalase and monooxygenase properties. The entrapment of MP-11 inside MCM-41 was confirmed by elemental analysis and UV-visible spectrum, with a red shift in the Soret band indicating that the heme group was in a hydrophobic microenvironment. Similarly to catalase, the catalyst Fe(III)MP11MCM41 exhibited specificity for hydrogen peroxide to be converted to a high-valence oxidized intermediate, Compound II. Also mimicking catalase, the cleavage of hydrogen peroxide by MP11MCM41 resulted in O2 production detected by a Clark electrode. Phenol was able to act as reducing agent of MP11MCM41 Compound II leading to the completion of a peroxidase cycle, as confirmed by UV-visible spectrometry and EPR measurements. The analysis of the reaction products by high performance liquid chromatogram coupled to tandem mass spectrometry (HPLC/MS) revealed 2,4-dihydroxyphenol as the product of phenol oxidation by MP11MCM41. Therefore, in addition to catalase activity, the catalyst MP11MCM41 also displayed monooxygenase properties, which was possible because the MP-11 heme iron promotes homolytic cleavage of the hydrogen peroxide generating hydroxyl radicals. With such characteristics, MCM-41-entrapped MP-11 is a promising catalyst for nanobiotechnological devices.

Journal of colloid and interface science, Jan 15, 2012

This article describes the covalent grafting of pyromellitimide and 1,4,5,8-naphthalenediimide, w... more This article describes the covalent grafting of pyromellitimide and 1,4,5,8-naphthalenediimide, which are organic semiconductors with very interesting electro-optical properties, onto the walls of mesoporous molecular sieves. The mesoporous materials MCM-41 and SBA-15 were first treated with 3-aminopropyltriethoxysilane, generating materials with a surface coverage of primary amino groups. These materials were further reacted with either pyromellitic dianhydride or 1,4,5,8-naphthalenetetracarboxylic dianhydride, generating surface-bound pyromellitimide or 1,4,5,8-naphthalenediimide, respectively. The success of the modification reactions was confirmed by elemental and thermogravimetric analyses, X-ray diffraction patterns and infrared, reflectance and fluorescence spectroscopies. The results indicated that the mesoporous structure of the new materials was preserved after the modification reactions and that the chromophores were included inside the mesoporous channels with stacked aromatic rings.