Antonio E H Machado | Universidade Federal de Uberlândia - Academia.edu

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Antonio E H Machado

Universidade Federal de Uberlândia, Instituto de Química, Full Professor, Senior Scholar

Universidade Federal de Uberlândia, Instituto de Química, Full Professor, Senior Scholar |

Environmental Sustainability

Is Ph.D. in Physical Chemistry (Universidade de São Paulo, Brazil), being a researcher with experience in areas of chemistry (organic photochemistry, spectroscopy and applications of quantum mechanics in chemistry), with research interests on the following topics: photocatalysis, energy conversion, application of methods from quantum mechanics in the study of photophysical and photochemical phenomena. Is actually full professor at Universidade Federal de Uberlândia, Brazil, and Productivity Research Fellow of the Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil.

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Papers

Rapid Preparation of (BiO)2CO3Nanosheets by Microwave-Assisted Hydrothermal Method with Promising Photocatalytic Activity Under UV-Vis Light

Journal of the Brazilian Chemical Society, 2015

Molecular modeling study on the possible polymers formed during the electropolymerization of 3-hydroxyphenylacetic acid

Journal of Molecular Graphics and Modelling, 2012

Quantum Efficiency of Hydroxyl Radical Formation in a Composite Containing Nanocrystalline TiO2 e Zinc Phthalocyanine, and the Nature of the Incident Radiation

Journal of Materials Science Research, 2013

Investigation of protonation effects on the electronic and structural properties of halogenated sulfonated porphyrins

Journal of Molecular Structure, 2015

ABSTRACT The present study aimed at evaluating pH effects on the electronic and structural proper... more ABSTRACT The present study aimed at evaluating pH effects on the electronic and structural properties of halogenated sulfonated porphyrins. We used UV–Vis absorption, fluorescence emission, and NMR spectroscopies, combined with quantum chemical calculations using Density Functional Theory. We observed that the presence of one or two halogen atoms (chlorine or fluorine) at ortho-position of phenyl ring reduces the flexibility of the porphyrin structures, making their protonation harder. Since the protonation of anionic porphyrins provides a convenient way for their aggregation, the protonation observed only in extremely acid environment is indicative of the low probability for the aggregation of these porphyrins, which is an important characteristic of an efficient photosensitizer. Furthermore, the enhancement in the absorbance (9–13.5 times) in the phototherapeutic window suggests that the protonation of halogenated sulfonated porphyrins could be a possible strategy for a higher photodynamic efficiency.

Dye Degradation Enhanced by Coupling Electrochemical Process and Heterogeneous Photocatalysis

Journal of the Brazilian Chemical Society, 2015

Metal oxides for photoinduced hydrogen production and dye-sensitized solar cell applications

1. Aims and Scope Currently, the research in renewable energy sources is intense due to the conce... more 1. Aims and Scope Currently, the research in renewable energy sources is intense due to the concerns about the global warming and other environmental issues related to the huge dependence of the global energy matrix on the fossil fuels. The enhancement in the participation of renewables requires the development of cost effective materials capable to produce fuels or electricity from solar light as well as from earth abundant green sources. The goal of the present work is to present the concepts and current research involving the application of metal oxide- based semiconductors in solar energy conversion. In the first section, the synthetic methodologies for production of metal oxides with different sizes and shapes are discussed and correlated to their optoelectronic properties. Following the discussion about morphology and electronic properties of metal oxides, the recent advances in heterogeneous photocatalytic hydrogen evolution are briefly discussed. Due to size limitations and the very intense research activity in this topic, we have focused the manuscript on TiO2-based systems, which is the most studied oxide in photocatalysis. Finally, in the third section, the use of metal oxides thin films in Dye-sensitized solar cells is explored. The role of film morphology, the deposition method and the oxide electronic properties on the light-to-current conversion efficiency is discussed based on the recent literature. The advances reported evidence the feasibility of large use application of metal oxide-based semiconductors in renewable solar energy systems.

Study of the spectroscopic properties and first hyperpolarizabilities of disperse azo dyes derived from 2-amino-5-nitrothiazole

Journal of Photochemistry and Photobiology A: Chemistry, 2008

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with

The bimolecular sensitization of nitric oxide release from weak interacting ruthenium units

Inorganica Chimica Acta, 2011

This work reports on the bimolecular sensitization of nitric oxide release from cis-[Ru(bpy)2(iso... more This work reports on the bimolecular sensitization of nitric oxide release from cis-[Ru(bpy)2(iso)NO](PF6)3 (1) (iso=isoquinoline and bpy=2,2′-bipyridine) by irradiating the MLCT transition of the chloro analog cis-[Ru(bpy)2(iso)Cl]PF6 (2). The compounds displayed peaks in the ESI-MS spectra at m/z 749.1 and m/z 578.1 ascribed, respectively, to ([1(NO0)−2PF6·CH3OH]2+) and ([2−PF6]+). In the cyclic voltammograms, the nitrosyl complex presented two redox waves related

Characterization of PLGA Microparticles as a Drug Carrier for 3-Ethoxycarbonyl-2H-Benzofuro[3,2-f]-1-Benzopyran-2-One. Ultrastructural Study of Cellular Uptake and Intracellular Distribution

Drug Delivery, 2006

Applications of Mesoporous Ordered Semiconductor Materials — Case Study of TiO2

Solar Radiation Applications, 2015

Determination of the Critical Micelle Concentration of Triton X-100 Using the Compound 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one as Fluorescent Probe

Orbital: The Electronic Journal of Chemistry, 2016

In the present study we estimated the Critical Micelle Concentration (CMC) of Triton X-100 in an ... more In the present study we estimated the Critical Micelle Concentration (CMC) of Triton X-100 in an aqueous buffered medium (PBS buffer, pH 7.4), using 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one (BDC), a push-pull compound, as extrinsic fluorescence probe. The CMC value found, 0.33 mmol L -1 , shows good agreement with data from literature obtained using the fluorescence probe technique. Additionally, the polarity, in terms of the E T (30) scale, and the viscosity of the micelle microenvironment in which the probe is preferentially allocated, was estimated as being 46.9 kcal mol -1 and 70.3 cP, respectively, confirming that this microdomain is polar and highly viscous, with characteristics of polyethylene glycol groups consisting in the palisade layer at the micelle-water interface. DOI: http://dx.doi.org/10.17807/orbital.v0i0.923

Manganese(ii) Schiff-base-mediated reversible deactivation controlled radical polymerization of vinyl acetate

New Journal of Chemistry

The manganese Schiff-base complexes were applied in the OMRP of vinyl acetate.

Photocontrolled reversible-deactivation radical polymerization of butyl acrylate mediated by Salen-type CoII complexes

European Polymer Journal

Characterization of a highly efficient N-doped TiO 2 photocatalyst prepared via factorial design

New J. Chem., 2016

The preparation of a highly efficient N-doped TiO2 photocatalyst was optimized by factorial desig... more

Treatment of Sanitary Landfill Leachate by Photo-Fenton Process: Effect of the Matrix Composition

Journal of the Brazilian Chemical Society, 2016

Synthesis and Antitumor Evaluation of Benzopsoralen Analogues

Chemistry & Biodiversity, 2007

Synthesis and antitumor evaluation of benzopsoralen analogues

Chemistry & …, 2007

Study of the spectroscopic properties and first hyperpolarizabilities of disperse azo dyes derived from 2-amino-5-nitrothiazole

Journal of Photochemistry and Photobiology. A, Chemistry

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with

Quantum mechanical investigation of polymer formation from aminophenols

by Odonírio Abrahão Jr. and Antonio E H Machado

Journal of Molecular Structure-Theochem, 2009

Photocatalytic degradation of lignin and lignin models, using titanium dioxide: the role of the hydroxyl radical

Chemosphere, 2000

Rapid Preparation of (BiO)2CO3Nanosheets by Microwave-Assisted Hydrothermal Method with Promising Photocatalytic Activity Under UV-Vis Light

Journal of the Brazilian Chemical Society, 2015

Molecular modeling study on the possible polymers formed during the electropolymerization of 3-hydroxyphenylacetic acid

Journal of Molecular Graphics and Modelling, 2012

Quantum Efficiency of Hydroxyl Radical Formation in a Composite Containing Nanocrystalline TiO2 e Zinc Phthalocyanine, and the Nature of the Incident Radiation

Journal of Materials Science Research, 2013

Investigation of protonation effects on the electronic and structural properties of halogenated sulfonated porphyrins

Journal of Molecular Structure, 2015

ABSTRACT The present study aimed at evaluating pH effects on the electronic and structural proper... more ABSTRACT The present study aimed at evaluating pH effects on the electronic and structural properties of halogenated sulfonated porphyrins. We used UV–Vis absorption, fluorescence emission, and NMR spectroscopies, combined with quantum chemical calculations using Density Functional Theory. We observed that the presence of one or two halogen atoms (chlorine or fluorine) at ortho-position of phenyl ring reduces the flexibility of the porphyrin structures, making their protonation harder. Since the protonation of anionic porphyrins provides a convenient way for their aggregation, the protonation observed only in extremely acid environment is indicative of the low probability for the aggregation of these porphyrins, which is an important characteristic of an efficient photosensitizer. Furthermore, the enhancement in the absorbance (9–13.5 times) in the phototherapeutic window suggests that the protonation of halogenated sulfonated porphyrins could be a possible strategy for a higher photodynamic efficiency.

Dye Degradation Enhanced by Coupling Electrochemical Process and Heterogeneous Photocatalysis

Journal of the Brazilian Chemical Society, 2015

Metal oxides for photoinduced hydrogen production and dye-sensitized solar cell applications

1. Aims and Scope Currently, the research in renewable energy sources is intense due to the conce... more 1. Aims and Scope Currently, the research in renewable energy sources is intense due to the concerns about the global warming and other environmental issues related to the huge dependence of the global energy matrix on the fossil fuels. The enhancement in the participation of renewables requires the development of cost effective materials capable to produce fuels or electricity from solar light as well as from earth abundant green sources. The goal of the present work is to present the concepts and current research involving the application of metal oxide- based semiconductors in solar energy conversion. In the first section, the synthetic methodologies for production of metal oxides with different sizes and shapes are discussed and correlated to their optoelectronic properties. Following the discussion about morphology and electronic properties of metal oxides, the recent advances in heterogeneous photocatalytic hydrogen evolution are briefly discussed. Due to size limitations and the very intense research activity in this topic, we have focused the manuscript on TiO2-based systems, which is the most studied oxide in photocatalysis. Finally, in the third section, the use of metal oxides thin films in Dye-sensitized solar cells is explored. The role of film morphology, the deposition method and the oxide electronic properties on the light-to-current conversion efficiency is discussed based on the recent literature. The advances reported evidence the feasibility of large use application of metal oxide-based semiconductors in renewable solar energy systems.

Study of the spectroscopic properties and first hyperpolarizabilities of disperse azo dyes derived from 2-amino-5-nitrothiazole

Journal of Photochemistry and Photobiology A: Chemistry, 2008

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with

The bimolecular sensitization of nitric oxide release from weak interacting ruthenium units

Inorganica Chimica Acta, 2011

This work reports on the bimolecular sensitization of nitric oxide release from cis-[Ru(bpy)2(iso... more This work reports on the bimolecular sensitization of nitric oxide release from cis-[Ru(bpy)2(iso)NO](PF6)3 (1) (iso=isoquinoline and bpy=2,2′-bipyridine) by irradiating the MLCT transition of the chloro analog cis-[Ru(bpy)2(iso)Cl]PF6 (2). The compounds displayed peaks in the ESI-MS spectra at m/z 749.1 and m/z 578.1 ascribed, respectively, to ([1(NO0)−2PF6·CH3OH]2+) and ([2−PF6]+). In the cyclic voltammograms, the nitrosyl complex presented two redox waves related

Characterization of PLGA Microparticles as a Drug Carrier for 3-Ethoxycarbonyl-2H-Benzofuro[3,2-f]-1-Benzopyran-2-One. Ultrastructural Study of Cellular Uptake and Intracellular Distribution

Drug Delivery, 2006

Applications of Mesoporous Ordered Semiconductor Materials — Case Study of TiO2

Solar Radiation Applications, 2015

Determination of the Critical Micelle Concentration of Triton X-100 Using the Compound 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one as Fluorescent Probe

Orbital: The Electronic Journal of Chemistry, 2016

In the present study we estimated the Critical Micelle Concentration (CMC) of Triton X-100 in an ... more In the present study we estimated the Critical Micelle Concentration (CMC) of Triton X-100 in an aqueous buffered medium (PBS buffer, pH 7.4), using 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one (BDC), a push-pull compound, as extrinsic fluorescence probe. The CMC value found, 0.33 mmol L -1 , shows good agreement with data from literature obtained using the fluorescence probe technique. Additionally, the polarity, in terms of the E T (30) scale, and the viscosity of the micelle microenvironment in which the probe is preferentially allocated, was estimated as being 46.9 kcal mol -1 and 70.3 cP, respectively, confirming that this microdomain is polar and highly viscous, with characteristics of polyethylene glycol groups consisting in the palisade layer at the micelle-water interface. DOI: http://dx.doi.org/10.17807/orbital.v0i0.923

Manganese(ii) Schiff-base-mediated reversible deactivation controlled radical polymerization of vinyl acetate

New Journal of Chemistry

The manganese Schiff-base complexes were applied in the OMRP of vinyl acetate.

Photocontrolled reversible-deactivation radical polymerization of butyl acrylate mediated by Salen-type CoII complexes

European Polymer Journal

Characterization of a highly efficient N-doped TiO 2 photocatalyst prepared via factorial design

New J. Chem., 2016

The preparation of a highly efficient N-doped TiO2 photocatalyst was optimized by factorial desig... more

Treatment of Sanitary Landfill Leachate by Photo-Fenton Process: Effect of the Matrix Composition

Journal of the Brazilian Chemical Society, 2016

Synthesis and Antitumor Evaluation of Benzopsoralen Analogues

Chemistry & Biodiversity, 2007

Synthesis and antitumor evaluation of benzopsoralen analogues

Chemistry & …, 2007

Study of the spectroscopic properties and first hyperpolarizabilities of disperse azo dyes derived from 2-amino-5-nitrothiazole

Journal of Photochemistry and Photobiology. A, Chemistry

The solvatochromism and other spectroscopic and photophysical characteristics of four azo dispers... more The solvatochromism and other spectroscopic and photophysical characteristics of four azo disperse dyes, derived from 2-amino-5-nitrothiazole, were evaluated and interpreted with the aid of experimental data and quantum mechanical calculations. For the non-substituted compound two conformers, E and Z, were proposed for the isolated molecules, being the second one considerably less stable. The optimization of these structures in combination with

Quantum mechanical investigation of polymer formation from aminophenols

by Odonírio Abrahão Jr. and Antonio E H Machado

Journal of Molecular Structure-Theochem, 2009

Photocatalytic degradation of lignin and lignin models, using titanium dioxide: the role of the hydroxyl radical

Chemosphere, 2000