Corina-Stefania Enache - Academia.edu (original) (raw)
Papers by Corina-Stefania Enache
Materials Research Bulletin, 2010
This study is concerning about optical and morphological properties of novel porphyrin doped sili... more This study is concerning about optical and morphological properties of novel porphyrin doped silica materials consisting in 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) encapsulated in silica matrices, exhibiting intensive absorption of light in the red-near IR region. The ...
Digest Journal of Nanomaterials and Biostructures
20-Tetrakis(4-pyridyl)-21H,23H-porphine (TPyP) molecules easily self-assemble into large highly o... more 20-Tetrakis(4-pyridyl)-21H,23H-porphine (TPyP) molecules easily self-assemble into large highly ordered domains. Their photophysical properties could be strongly affected by changes in their aggregation state. The present study is concerned about the synthesis and UV-vis, FT-IR, 1 H-NMR and solid-state 13 C-NMR spectroscopic characterization of TPyP. Among the investigations, one focus is about the comparative study of the absorption and fluorescence spectra of meso-tetrapyridylporphyrine and its Zn complex in diverse solvents, various concentrations and different pH conditions.
Materials Research Bulletin, 2010
Current Organic Chemistry, 2012
ABSTRACT Abstract: The present report is concerned with the designing, obtaining and characteriza... more ABSTRACT Abstract: The present report is concerned with the designing, obtaining and characterization of novel light –sensitive molecules, belonging to second generation meso-tetraarylporphyrin derivatives. A new structure of asymmetrical A3B porphyrin, namely: 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin was synthesized in fair yield by multicomponent reaction and characterized by 1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC, TLC, AFM and XRD techniques. Tailoring porphyrins by introducing pyridyl substituent in one of the meso-aryl groups confers some degree of hydrophilicity and may cause absorption and fluorescence emission bands in the long wavelength region. Besides, as it was expected, because of the relatively rigid planar structure, due to substitution with three phenoxy substituents, this porphyrin is characterized by a value of 0.219 for fluorescence quantum yield, a higher value in comparison with usual porphyrins. In solution, by UV-vis and fluorescence spectra, the effect of pH and concentration upon H and J aggregates of the porphyrin was discussed. X-ray diffraction and atomic force microscopy investigations proved that this newly synthesized porphyrin is able to generate stable self-assembly in preferred orientations, such as multilayer of lamellar triangles, densely packed and homogeneous, with dimensions around 440nm, finally forming pyramidal type structures. CHCl3 favor the spiral organization of the pyramids so that rings and even tubes of various diameters ranging from 1μm to 4.5 μm were formed.
Materials Research Bulletin, 2009
The present study is dealing with the obtaining of transparent hybrid silica materials encapsulat... more The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction ...
The Open Chemical and Biomedical Methods Journal, 2009
1Department of Organic Chemistry, Institute of Chemistry Timisoara of Romanian Academy, 24 M. Vit... more 1Department of Organic Chemistry, Institute of Chemistry Timisoara of Romanian Academy, 24 M. Viteazul Ave, 300223-Timisoara, Romania 2Department of Inorganic Chemistry, Faculty of Chemistry-Biology-Geography, West University of Timisoara, Pestalozzi Street No. 16, ...
Processing and Application of Ceramics, 2009
The present work contributes to elucidating the differences between silica gels obtained by low d... more The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic fi eld, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS) measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution -about 90 % of the pores for this sample fall into the mesopore range (2-50 nm). SANS data reveal the formation of primary structural units of sizes around 1.5-2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath.
Summary Mitochondria have emerged as key players in cardioprotection against ischemia/reperfusion... more Summary Mitochondria have emerged as key players in cardioprotection against ischemia/reperfusion (I/R) injury. Diazoxide (Dx) has been shown to reduce infarct size in several experimental models through the opening of mitochondrial ATP-dependent potassium channels (mKATP) and also to exert a substrate-dependent effect on mitochondrial respiration. The aim of the present study performed in mitochondria isolated from rat hearts subjected to
Solid State Ionics, 2002
Presently, there is a great interest in synthesis of iron and iron oxides particles embedded in s... more Presently, there is a great interest in synthesis of iron and iron oxides particles embedded in silica matrix that have potential application to information storage, magnetic refrigeration, magneto-optical solid devices, magnetic resonance imaging enhancement, etc. The ...
Physica Scripta, 2012
Nanocrystalline zinc aluminate, ZnAl2O4, was obtained by the hydrothermal method. After hydrother... more Nanocrystalline zinc aluminate, ZnAl2O4, was obtained by the hydrothermal method. After hydrothermal treatment the samples were heated at different temperatures. The precursors used in the hydrothermal synthesis of ZnAl2O4 were zinc nitrate hexahydrate and aluminum nitrate nonahydrate. Sodium hydroxide was used as a basic source. The obtained samples were analyzed by x-ray diffraction. The optical properties of nanocrystalline zinc aluminate
Materials Research Bulletin, 2009
The present study is dealing with the obtaining of transparent hybrid silica materials encapsulat... more The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction ...
Materials Research Bulletin, 2009
Hybrid porphyrinsilica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsula... more Hybrid porphyrinsilica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsulated in silica matrices were obtained by solgel method. The hydrolysis and condensation reactions were performed by using tetraethylorthosilicate as precursor, either in one-step acid or in ...
Journal of Macromolecular Science, Part B, 2013
ABSTRACT Molecular properties and aggregation behavior of a polysiloxane with grafted side chain ... more ABSTRACT Molecular properties and aggregation behavior of a polysiloxane with grafted side chain groups consisting of asymmetrical hydroxy-functionalized porphyrin were studied in dilute solutions. In order to understand the mechanism of aggregation of the polymeric porphyrin derivatives, several analyses of chloroform solutions were performed permitting comparison of the data obtained by means of different techniques. Molar mass and hydrodynamic size of the macromolecules were obtained using the methods of analytical ultracentrifugation, isothermal translational diffusion, and viscometry. Long distance interactions between macromolecules in dilute solutions were detected with static light scattering. With increasing the concentration of the solutions, the electronic and fluorescence spectra bands assigned to generation of H and J aggregates became apparent. The organization of aggregates, which seemed to be favored by chloroform, was visualized by atomic force microscopy images that displayed sponge-like morphology, small triangular particles, characteristic of H aggregates, and nano or micro-structured ring geometries obtained by the side-by-side J-process, coexisting together.
Chemistry of Materials, 2004
Fe 2 O 3 nanoparticles embedded in a SiO 2 matrix have been synthesized by sol-gel chemistry and ... more Fe 2 O 3 nanoparticles embedded in a SiO 2 matrix have been synthesized by sol-gel chemistry and high temperature heat treatments. Virtually pure -Fe 2 O 3 (in excess of 93%) is obtained, although a two-phase mixture, -Fe 2 O 3 + R-Fe 2 O 3 , is observed for Fe 2 O 3 /SiO 2 ratios greater than 37 wt %. The -Fe 2 O 3 nanoparticles are stable up to ∼1600 K. Optimized -Fe 2 O 3 nanoparticles are ferrimagnetic, with a Curie temperature T C ≈ 510 K, and remarkably high values of room-temperature coercivity, H C ) 20 kOe.
analelesnbc.ro
It is widely accepted that mitochondria contribute to their own damage in the settings of experim... more It is widely accepted that mitochondria contribute to their own damage in the settings of experimental ischemia/reperfusion injury. The aim of the present work was to investigate the degree of mitochondrial dysfunction elicited by an in vivo rat heart model of regional ischemia/reperfusion injury. Mitochondria were isolated from ischemic and non-ischemic zones rat hearts subjected to 30 min of regional ischemia by coronary ligation and 15 min of reperfusion. Oxygen consumption was assessed by polarographic oxymetry in a Clark-type electrode in the presence of complex I substrates (glutamate/malate) and complex II (succinate). State 3 respiration rate and the respiratory control ratio for glutamate/malate were significantly decreased in mitochondria isolated from the ischemic area, suggesting an early alteration of complex I supported respiration (p < 0.01 vs. non-ischemic area). In another set of experiments mitochondrial calcium retention capacity was evaluated by luminescence spectroscopy using the calcium-sensitive probe Calcium Green 5N and mitochondrial swelling was monitored as the decrease in light scattering at 520 nm. In the presence of complex IIdependent substrate, less calcium was required to zone induce permeability transition, suggesting the pre-existence of calcium overload in mitochondria isolated from ischemic zone vs. non-ischemic zone. Mitochondria isolated from the ischemic (vs. non-ischemic) zone presented an increased rate of swelling in the case of complex I supported respiration. These results are suggestive for an early damage to the phosphorylation apparatus at complex I in mitochondria isolated at reperfusion after regional ischemia in the in vivo rat hearts.
Acta periodica technologica, 2004
Sol-gel method and successive thermal treatments in vacuum and nitrogen atmosphere were employed ... more Sol-gel method and successive thermal treatments in vacuum and nitrogen atmosphere were employed to synthesize magnetite nanoparticles isolate them with the aid of amorphous silica. Thermogravimetric and differential thermal analyses coupled with mass spectrometry, X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and vibrating sample magnetometry measurements were performed on the obtained nanocomposites. The effect of atmosphere on the formation of magnetite phase was remarkable.
Acta periodica technologica, 2004
The purpose of the study was to investigate the appearance of certain microstructures developing ... more The purpose of the study was to investigate the appearance of certain microstructures developing in the SiO 2 /PVA nanocomposite xerogels at different temperatures by small-angle neutron scattering (SANS). The samples were prepared by the alcoxide route of the sol-gel method. The SANS measurements were performed over a q (scattering vector) range from 0.05 to 3.7 nm -1 , providing structural information at length scales (2π/q) between approximately 1 and 100 nm. The measured small-angle scattering intensities of silica and silica/PVA samples aged at 60°C and heat-treated at different temperatures, are presented in log-log plots. It is shown that both the molecular mass of organic and the temperature of thermal treatment have strong influence on transition tendency from mass fractal toward surface fractal structures.
Materials Research Bulletin, 2010
This study is concerning about optical and morphological properties of novel porphyrin doped sili... more This study is concerning about optical and morphological properties of novel porphyrin doped silica materials consisting in 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) encapsulated in silica matrices, exhibiting intensive absorption of light in the red-near IR region. The ...
Digest Journal of Nanomaterials and Biostructures
20-Tetrakis(4-pyridyl)-21H,23H-porphine (TPyP) molecules easily self-assemble into large highly o... more 20-Tetrakis(4-pyridyl)-21H,23H-porphine (TPyP) molecules easily self-assemble into large highly ordered domains. Their photophysical properties could be strongly affected by changes in their aggregation state. The present study is concerned about the synthesis and UV-vis, FT-IR, 1 H-NMR and solid-state 13 C-NMR spectroscopic characterization of TPyP. Among the investigations, one focus is about the comparative study of the absorption and fluorescence spectra of meso-tetrapyridylporphyrine and its Zn complex in diverse solvents, various concentrations and different pH conditions.
Materials Research Bulletin, 2010
Current Organic Chemistry, 2012
ABSTRACT Abstract: The present report is concerned with the designing, obtaining and characteriza... more ABSTRACT Abstract: The present report is concerned with the designing, obtaining and characterization of novel light –sensitive molecules, belonging to second generation meso-tetraarylporphyrin derivatives. A new structure of asymmetrical A3B porphyrin, namely: 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin was synthesized in fair yield by multicomponent reaction and characterized by 1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC, TLC, AFM and XRD techniques. Tailoring porphyrins by introducing pyridyl substituent in one of the meso-aryl groups confers some degree of hydrophilicity and may cause absorption and fluorescence emission bands in the long wavelength region. Besides, as it was expected, because of the relatively rigid planar structure, due to substitution with three phenoxy substituents, this porphyrin is characterized by a value of 0.219 for fluorescence quantum yield, a higher value in comparison with usual porphyrins. In solution, by UV-vis and fluorescence spectra, the effect of pH and concentration upon H and J aggregates of the porphyrin was discussed. X-ray diffraction and atomic force microscopy investigations proved that this newly synthesized porphyrin is able to generate stable self-assembly in preferred orientations, such as multilayer of lamellar triangles, densely packed and homogeneous, with dimensions around 440nm, finally forming pyramidal type structures. CHCl3 favor the spiral organization of the pyramids so that rings and even tubes of various diameters ranging from 1μm to 4.5 μm were formed.
Materials Research Bulletin, 2009
The present study is dealing with the obtaining of transparent hybrid silica materials encapsulat... more The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction ...
The Open Chemical and Biomedical Methods Journal, 2009
1Department of Organic Chemistry, Institute of Chemistry Timisoara of Romanian Academy, 24 M. Vit... more 1Department of Organic Chemistry, Institute of Chemistry Timisoara of Romanian Academy, 24 M. Viteazul Ave, 300223-Timisoara, Romania 2Department of Inorganic Chemistry, Faculty of Chemistry-Biology-Geography, West University of Timisoara, Pestalozzi Street No. 16, ...
Processing and Application of Ceramics, 2009
The present work contributes to elucidating the differences between silica gels obtained by low d... more The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic fi eld, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS) measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution -about 90 % of the pores for this sample fall into the mesopore range (2-50 nm). SANS data reveal the formation of primary structural units of sizes around 1.5-2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath.
Summary Mitochondria have emerged as key players in cardioprotection against ischemia/reperfusion... more Summary Mitochondria have emerged as key players in cardioprotection against ischemia/reperfusion (I/R) injury. Diazoxide (Dx) has been shown to reduce infarct size in several experimental models through the opening of mitochondrial ATP-dependent potassium channels (mKATP) and also to exert a substrate-dependent effect on mitochondrial respiration. The aim of the present study performed in mitochondria isolated from rat hearts subjected to
Solid State Ionics, 2002
Presently, there is a great interest in synthesis of iron and iron oxides particles embedded in s... more Presently, there is a great interest in synthesis of iron and iron oxides particles embedded in silica matrix that have potential application to information storage, magnetic refrigeration, magneto-optical solid devices, magnetic resonance imaging enhancement, etc. The ...
Physica Scripta, 2012
Nanocrystalline zinc aluminate, ZnAl2O4, was obtained by the hydrothermal method. After hydrother... more Nanocrystalline zinc aluminate, ZnAl2O4, was obtained by the hydrothermal method. After hydrothermal treatment the samples were heated at different temperatures. The precursors used in the hydrothermal synthesis of ZnAl2O4 were zinc nitrate hexahydrate and aluminum nitrate nonahydrate. Sodium hydroxide was used as a basic source. The obtained samples were analyzed by x-ray diffraction. The optical properties of nanocrystalline zinc aluminate
Materials Research Bulletin, 2009
The present study is dealing with the obtaining of transparent hybrid silica materials encapsulat... more The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction ...
Materials Research Bulletin, 2009
Hybrid porphyrinsilica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsula... more Hybrid porphyrinsilica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsulated in silica matrices were obtained by solgel method. The hydrolysis and condensation reactions were performed by using tetraethylorthosilicate as precursor, either in one-step acid or in ...
Journal of Macromolecular Science, Part B, 2013
ABSTRACT Molecular properties and aggregation behavior of a polysiloxane with grafted side chain ... more ABSTRACT Molecular properties and aggregation behavior of a polysiloxane with grafted side chain groups consisting of asymmetrical hydroxy-functionalized porphyrin were studied in dilute solutions. In order to understand the mechanism of aggregation of the polymeric porphyrin derivatives, several analyses of chloroform solutions were performed permitting comparison of the data obtained by means of different techniques. Molar mass and hydrodynamic size of the macromolecules were obtained using the methods of analytical ultracentrifugation, isothermal translational diffusion, and viscometry. Long distance interactions between macromolecules in dilute solutions were detected with static light scattering. With increasing the concentration of the solutions, the electronic and fluorescence spectra bands assigned to generation of H and J aggregates became apparent. The organization of aggregates, which seemed to be favored by chloroform, was visualized by atomic force microscopy images that displayed sponge-like morphology, small triangular particles, characteristic of H aggregates, and nano or micro-structured ring geometries obtained by the side-by-side J-process, coexisting together.
Chemistry of Materials, 2004
Fe 2 O 3 nanoparticles embedded in a SiO 2 matrix have been synthesized by sol-gel chemistry and ... more Fe 2 O 3 nanoparticles embedded in a SiO 2 matrix have been synthesized by sol-gel chemistry and high temperature heat treatments. Virtually pure -Fe 2 O 3 (in excess of 93%) is obtained, although a two-phase mixture, -Fe 2 O 3 + R-Fe 2 O 3 , is observed for Fe 2 O 3 /SiO 2 ratios greater than 37 wt %. The -Fe 2 O 3 nanoparticles are stable up to ∼1600 K. Optimized -Fe 2 O 3 nanoparticles are ferrimagnetic, with a Curie temperature T C ≈ 510 K, and remarkably high values of room-temperature coercivity, H C ) 20 kOe.
analelesnbc.ro
It is widely accepted that mitochondria contribute to their own damage in the settings of experim... more It is widely accepted that mitochondria contribute to their own damage in the settings of experimental ischemia/reperfusion injury. The aim of the present work was to investigate the degree of mitochondrial dysfunction elicited by an in vivo rat heart model of regional ischemia/reperfusion injury. Mitochondria were isolated from ischemic and non-ischemic zones rat hearts subjected to 30 min of regional ischemia by coronary ligation and 15 min of reperfusion. Oxygen consumption was assessed by polarographic oxymetry in a Clark-type electrode in the presence of complex I substrates (glutamate/malate) and complex II (succinate). State 3 respiration rate and the respiratory control ratio for glutamate/malate were significantly decreased in mitochondria isolated from the ischemic area, suggesting an early alteration of complex I supported respiration (p < 0.01 vs. non-ischemic area). In another set of experiments mitochondrial calcium retention capacity was evaluated by luminescence spectroscopy using the calcium-sensitive probe Calcium Green 5N and mitochondrial swelling was monitored as the decrease in light scattering at 520 nm. In the presence of complex IIdependent substrate, less calcium was required to zone induce permeability transition, suggesting the pre-existence of calcium overload in mitochondria isolated from ischemic zone vs. non-ischemic zone. Mitochondria isolated from the ischemic (vs. non-ischemic) zone presented an increased rate of swelling in the case of complex I supported respiration. These results are suggestive for an early damage to the phosphorylation apparatus at complex I in mitochondria isolated at reperfusion after regional ischemia in the in vivo rat hearts.
Acta periodica technologica, 2004
Sol-gel method and successive thermal treatments in vacuum and nitrogen atmosphere were employed ... more Sol-gel method and successive thermal treatments in vacuum and nitrogen atmosphere were employed to synthesize magnetite nanoparticles isolate them with the aid of amorphous silica. Thermogravimetric and differential thermal analyses coupled with mass spectrometry, X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and vibrating sample magnetometry measurements were performed on the obtained nanocomposites. The effect of atmosphere on the formation of magnetite phase was remarkable.
Acta periodica technologica, 2004
The purpose of the study was to investigate the appearance of certain microstructures developing ... more The purpose of the study was to investigate the appearance of certain microstructures developing in the SiO 2 /PVA nanocomposite xerogels at different temperatures by small-angle neutron scattering (SANS). The samples were prepared by the alcoxide route of the sol-gel method. The SANS measurements were performed over a q (scattering vector) range from 0.05 to 3.7 nm -1 , providing structural information at length scales (2π/q) between approximately 1 and 100 nm. The measured small-angle scattering intensities of silica and silica/PVA samples aged at 60°C and heat-treated at different temperatures, are presented in log-log plots. It is shown that both the molecular mass of organic and the temperature of thermal treatment have strong influence on transition tendency from mass fractal toward surface fractal structures.