Anabela S Oliveira | IPP - Polytechnic Institute of Portalegre (original) (raw)
Papers by Anabela S Oliveira
Journal of Luminescence, 1994
ABSTRACT
revistadechimie.ro
REV. CHIM. (Bucharest) ♦ 62♦ No. 4 ♦ 2011 http://www.revistadechimie.ro 462 ... A Study of the Th... more REV. CHIM. (Bucharest) ♦ 62♦ No. 4 ♦ 2011 http://www.revistadechimie.ro 462 ... A Study of the Thickness of TiO ... Photocatalytic Decomposition of Soluble Indigo Blue Dye ... ANABELA S. OLIVEIRA1,2*, ENRICO M. SAGGIORO3, NÁDIA R. BARBOSA4 , ANDRÉ MAZZEI5, ...
WIT Transactions on Ecology and the Environment, 2012
ABSTRACT The farming and agro-industrial sector generates large amounts of organic residues which... more ABSTRACT The farming and agro-industrial sector generates large amounts of organic residues which have a high energetic potential and in most cases are not recovered. Various technologies, including those for energy and agricultural applications, have been considered for the economical valorization of these residues. In this work, we show the results of a study on the potential use of some agro-industrial residues produced in the Portuguese Alto-Alentejo region, in particular, coffee husks, and forest and vineyards residues. The study was conducted in a pilot thermal gasification plant, installed at Portalegre’s Industrial Park based on the fluidized bed technology, with a processing capacity of 70 kg/h, and operating at around 800ºC. The gasification tests were performed continuously for several days, using different waste in order to optimize the heat value and composition of produced syngas. A comparative evaluation of the economic viability of the use of this waste as raw material for the commercial production of synthesis gas and synthetic city gas was made. The results achieved allow the conclusion that the waste biomasses studied show interesting features for use as syngas raw material. Keywords: biofuel, pilot plant, gasification, fluidized bed, syngas. 1 Introduction Bioenergy and biofuels are one of the most important alternatives to fuel production to minimize the continuous depletion of fossil fuel resources and the increasing concerns with environmental issues. Organic living matter, or biomass, in energy terms, is no more than a form of chemical storage of solar electromagnetic energy. When the bonds between carbon, hydrogen and oxygen
Waste and Biomass Valorization, 2014
ABSTRACT The wine industry, an important economic activity in Portugal, particularly in the Alto-... more ABSTRACT The wine industry, an important economic activity in Portugal, particularly in the Alto-Alentejo region, generates large amounts of residues, specially, the pruning of the vines. Various technologies, including energy and agricultural applications, have been considered for the economical valorization of these residues. In this work the results of a study on the potential use of vines pruning biomasses as a source for syngas (gasification gas) production by thermal gasification are presented. The study was conducted in a pilot thermal gasification plant, installed at Portalegre’s Industrial Park. The unit is based on fluidized bed technology, with a processing capacity of 70 kg/h, and operates at 800 °C. The gasification tests were performed continuously for several days, using pellets of mixtures with different mass ratios of vine pruning and wood, in order to optimize the heat value and the composition of produced gas and condensate obtained. A thermodynamic model were developed to allow simulation of the biomass gasification process in a fluidized bed gasifier and to anticipate the composition of the produced gas from the biomass elemental analysis and the prevailing operational conditions. Experimental results fit quite well to the used model. Results show that vines pruning biomasses have interesting features for use as gasification gas raw-material.
Journal of Photochemistry and Photobiology A: Chemistry, 2003
The quantum yields for singlet oxygen generation of several squarylium cyanine dyes derived from ... more The quantum yields for singlet oxygen generation of several squarylium cyanine dyes derived from benzothiazole, benzoselenazole and quinoline, displaying absorption within the so-called "phototherapeutic window" (600-1000 nm), were determined, envisioning their potential usefulness for photodynamic therapy (PDT). The determination was performed by a direct method measuring the luminescence decay of the dyes in the near infrared. Considering the absorption and the quantum yields displayed by some of the dyes, these seemed to be potential candidates as sensitizers for PDT.
Journal of Photochemistry and Photobiology A: Chemistry, 2004
Several symmetrical N-methylamino-and N,N-diethylaminosquarylium cyanine dyes bearing benzothiazo... more Several symmetrical N-methylamino-and N,N-diethylaminosquarylium cyanine dyes bearing benzothiazole, benzoselenazole and quinoline nuclei, displaying strong absorption within the "phototherapeutic window" (600-1000 nm), were investigated for the efficiency of singlet oxygen production, aiming their potential sensitising ability for photodynamic therapy (PDT). The assessment was performed determining the corresponding quantum yields of singlet oxygen generation, measuring the luminescence decay of the dyes in the near infrared. By combining the exhibited absorption and the obtained quantum yields, some of the dyes can be regarded as potential candidates as sensitizers for PDT.
WIT Transactions on Ecology and the Environment, 2013
ABSTRACT The presence of emergent pollutants in waters and wastewaters are an issue of increasing... more ABSTRACT The presence of emergent pollutants in waters and wastewaters are an issue of increasing concern due to the risk they pose to human and environmental health. Cancer Photodynamic Therapy photosensitizers and their metabolites and photodegradation products are pharmaceutical substances that after treatment will be eliminated from the human body and will eventually reach water bodies. Porphyrins are well established PDT sensitizers and cyanine dyes are promising candidates for the same use. In that way it is important to know how those compounds degrade once they reach water bodies and to find efficient treatment methodologies in case they are persistent. In this paper the simulated solar light photodegradation of a porphyrin (Zinctetraphenylporphyrin) and of a cyanine dye (3,3´-diethylindocarbocyanine iodide) in water was investigated, in the absence and in the presence of the most used photocatalyst for semiconductor photocatalysis: Titanium dioxide (TiO2). We observed that the porphyrin (1x10-3M) did not undergo photodegradation in the absence of photocatalyst and that in its presence the photodegradation process was strongly promoted (60% photodegradation reached after 1 hour of irradiation with 0,01g of TiO2). The
Journal of the Serbian Chemical Society, 2008
A series of four Zn(II) complexes with asymmetrical porphyrinic ligands were synthesized: [5-(4-h... more A series of four Zn(II) complexes with asymmetrical porphyrinic ligands were synthesized: [5-(4-hydroxyphenyl)-10,15,20-triphenyl-21H,23H-porphinato]Zn(II) (Zn(II)TPPOH P ), [5-(3-hydroxyphenyl)-10,15,20-triphenyl-21H,23H--porphinato]Zn(II) (Zn(II)TPPOH M ), [5-(2-hydroxyphenyl)-10,15,20-triphenyl--21H,23H-Zn(II)-porphinato]Zn(II) (Zn(II)TPPOH O ) and the well-known (5,10,15,20--tetraphenyl-21H,23H-porphinato]Zn(II) (Zn(II)TPP) as reference, in a 1:1 mole ratio. In all cases, the free-base porphyrin served as a tetradentate ligand through the four pyrrole nitrogen atoms. The complexes were characterized by elemental analysis, FTIR and UV-Vis spectroscopy, which fully confirmed the structure of the complexes. UV-Vis showed that the spectral absorption of the four complexes was blue-shifted by at least 50 nm compared to that of the free ligands. Also important structural data were obtained from several different NMR experiments (including 1 H-NMR, 13 C-NMR, DEPT, COSY, HMBC and HMQC). Influences of external substituents on the porphyrin ring were observed.
Molecules (Basel, Switzerland), 2015
In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3... more In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin and Cu(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin were synthesized, and characterized from a spectral and biological point of view. The study provided data concerning the behavior of identical external substituents vs. two different core insertions. Some of the properties of the proposed tetrapyrrolic structures were highlighted, having photodynamic therapy of cancer as a targeted biomedical application. Elemental analysis, NMR, FTIR and UV-Vis data in various solvents were provided. A preliminary in vitro study on normal and cancer cultured cells was carried out for biocompatibility assessment in dark conditions. The preliminary in vitro study performed on human peripheral mononuclear cells exposed to tetrapyrrolic compounds (2 µM) showed that the proposed compounds had a convenient cytotoxic profile on human normal peripheral blo...
Biomedical Engineering - From Theory to Applications, 2011
Toxicology Letters, 2011
It is well known that photosensitizing agents based on porphyrins structures tend to accumulate p... more It is well known that photosensitizing agents based on porphyrins structures tend to accumulate preferentially in tumor cells and less in their normal counterparts. Based on this capacity they were utilized in therapy but their fluorescent properties may be also valuable for imagistic purposes. Our aim was to establish the capacity of some porphyrin families to serve as organelles/cell/tissue markers, thus setting up the cytotoxic outline of these compounds was the first objective of the project. In this view, we have synthesized some novel copper (II) and zinc (II) porphyrinic complexes intended for further development in cellular imagistic procedures. We have evaluated the dark cytotoxicity of the compounds on cell lines (U937) and isolated peripheral blood mononuclear cells (PBMC) from healthy and cancer patients. Several experimental protocols were used for cellular viability and proliferation capacity. Cellular uptake yield and efflux capacity of porphyrins were evaluated by flow-cytometry. Obtained data have proven the non-toxic nature of the novel compounds even at high doses. Furthermore, the best cellular uptake was registered after prolonged incubation. Human PBMC data revealed a different pattern of cellular response to the new complexes, suggesting an anti-tumoral action upon PBMC isolated from tumor bearing patients. Data gathered by confocal microscopy suggested that these compounds can be good candidates for cellular markers, especially in the case of normal PBMC cells. Further data will pin-point the exact intracellular compartment and the accurate tracker capacity of these fluorescent probes.
Photochemical & Photobiological Sciences, 2006
Diffuse reflectance and luminescence techniques were used to study the photophysics and photochem... more Diffuse reflectance and luminescence techniques were used to study the photophysics and photochemistry of pyrene within p-tert-butylcalix [n]arenes with n = 4, 6, and 8, and to study their ability to form inclusion complexes in heterogeneous media. Evidences for inclusion complex formation were found for the three hosts under study. Ground state diffuse reflectance results have shown the formation of ground state dimers of pyrene inside the cavity of calix[6]arene and calix[8]arene, with this feature much more evident for calix arene. For calix[4]arene, only a monomer fits inside the cavity and the presence of pyrene microcrystals outside the cavity was detected. A luminescence lifetime distribution analysis was performed, revealing the presence of prompt emissions from the pyrene microcrystals outside the cavity in the case of calix[4]arene and from the constrained dimers inside the cavities of calix[6]arene and calix[8]arene. Transient absorption results have shown the presence of pyrene radical cation and also of trapped electrons for the three hosts under study. The formation of the phenoxyl radical of the calixarene following the laser pulsed excitation of pyrene at 355 nm is increased for calix[6]arene and calix arene. This feature is particularly relevant for calix[6]arene, suggesting a very favourable situation for the hydrogen atom abstraction to occur. The analysis of the degradation products revealed the presence of hydroxypyrene as a major photodegradation product for the three hosts. Dihydro-hydroxypyrene was also formed in the case of calix[6]arene and calix[8]arene. The formation of the calixarene's phenoxyl radical and subsequent hydrogen abstraction is consistent with the formation of dihydro-dihydroxypyrene.
Molecules, 2010
Cu(II) complexes with asymmetrical and symmetrical porphyrinic ligands were synthesized with supe... more Cu(II) complexes with asymmetrical and symmetrical porphyrinic ligands were synthesized with superior yields using microwave irradiation. The paper presents the synthesis of 5-(3-hydroxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl)-21,23-Cu(II)porphine in comparison to its symmetrical complex 5,10,15,20-meso-tetrakis-(4-carboxymethylphenyl)-21,23-Cu(II) porphine. The two compounds were characterized by FT-IR, UV-Vis and EPR spectroscopy, which fully confirmed the structures. The spectral molecular absorption properties of the porphyrinic complexes were studied in organic solvents (methanol, ethanol, iso-propanol, dimethyl sulfoxide, dimethylformamide and methylene chloride), and the influence of the solvent polarity on the absorbance maxima is described. In order to establish their future potential in biomedical applications preliminary toxicological studies consisting of viability and proliferation of standard tumor cell lines
Macromolecules, 1998
Rhodamine B isothiocyanate was adsorbed onto microcrystalline cellulose by two different methods:... more Rhodamine B isothiocyanate was adsorbed onto microcrystalline cellulose by two different methods: deposition from ethanolic and aqueous solutions followed by solvent evaporation and also from aqueous solutions in equilibrium with the powdered solid and following a dyeing protocol. After the above-mentioned samples were carefully washed, the fluorescence quantum yields (φ F) determined were about 0.40 ( 0.03 and 0.28 ( 0.03 for ethanol and water, respectively, solvents that efficiently swell cellulose, when these two solvents were used for sample preparation with the first method, while for dyed samples φF is only 0.10 ( 0.05. These values for φF can be compared with 0.70 ( 0.03 obtained for rhodamine B entrapped in the polymer chains of microcrystalline cellulose. X-ray photoelectron spectroscopic studies present evidence for a smaller positive charge density on the nitrogen atom for dyed samples when compared with the adsorbed ones. This is compatible with nitrogen atoms, which do not participate in the conjugated system. These findings indicate that rhodamine B has different conformers in dyed samples as compared to adsorbed samples. In the former case, the chemical bond, anchoring the dye to microcrystalline cellulose, leads to nonplanar conformers with smaller φ F and fluorescence lifetime (τF) values. In the latter case, planar conformers predominate, with the consequent increase of both lifetime and fluorescent quantum yield.
Langmuir, 1997
1,1′-Diethyl-2,2′-cyanine iodide and 1,1′-diethyl-2,2′-carbocyanine iodide were adsorbed onto mic... more 1,1′-Diethyl-2,2′-cyanine iodide and 1,1′-diethyl-2,2′-carbocyanine iodide were adsorbed onto microcrystalline cellulose by two different methods: by deposition from ethanolic solutions, followed by solvent evaporation, and also from ethanolic solutions in equilibrium with the powdered solid. Within experimental error, both methods provided the same fluorescence quantum yield of the adsorbed dyes in the concentration range 0.01-5.0 µmol of dye per gram of cellulose. Ethanol swells cellulose and some dye molecules become entrapped within the natural polymer chains and in close contact with the substrate. The use of dichloromethane, a solvent which does not swell microcrystalline cellulose, provides samples which exhibit a smaller fluorescence quantum yield. This is consistent with a larger degree of mobility (and also the formation of nonplanar and less emissive conformers) of the cyanines adsorbed on the surface of the solid substrate, while entrapment provides more rigid, planar, and emissive fluorophers. At the same time, the adsorption isotherms of 2,2′-cyanine on cellulose from alcoholic and dichloromethane solutions show that the specific cellulose surface area accessible for dye adsorption is larger when adsorption is from ethanol rather than from dichloromethane. For 2,2′-cyanine the fluorescence quantum yields (Φ F) determined were about 0.08 when dichloromethane (a solvent which does not swell cellulose) was used for sample preparation, while with ethanol ΦF was approximately 0.30. These values are about 3 orders of magnitude higher than those in solution, showing the importance of the rigid dry matrix in reducing the nonradiative pathways of deactivation of the (π, π*) first excited singlet state of this cyanine. X-ray photoelectron spectroscopic studies present evidence for hydrogen bonding of 2,2′-cyanine to cellulose at low loadings and for the formation of aggregates at higher loadings adsorbing from both ethanol and dichloromethane. This hydrogen bonding is assigned as involving dye molecules entrapped within the cellulose chains. On the other hand, for 2,2′-carbocyanine, evidence exists for an increase of hydrogen bonding with dye loading. This result together with evidence from ground-state diffuse reflectance absorption and luminescence is compatible with dye molecules being firmly bonded to the substrate by one of the nitrogen atoms, with the other unbound.
Journal of King Saud University - Science, 2011
The reaction of anthrone 1 with 4-aminoantipyrine and thiosemicarbazide afforded 4-(anthracen-9(1... more The reaction of anthrone 1 with 4-aminoantipyrine and thiosemicarbazide afforded 4-(anthracen-9(10H)-ylideneamino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one 2 and anthracen-9(10H)-one thiosemicarbazone 5, respectively. Oxidation of compound 2 with potassium permanganate gave 4-(anthracen-9(10H)-ylideneamino)-1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H pyrazole-5-carboxylic acid 3 which on reaction with o-phenylenediamine gave 4-(anthracen-9(10H)-ylideneamino)-5-(1H-benzimidazol-2-yl)-1-methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one 4. Furthermore, compound 5 was condensed with different substituted phenacyl bromide to give a series of 2-(anthracen-9(10H)-ylidenehydrazono)-5-substituted-2,3-dihydro-1H-thiazole 6a-g. Compound 5 also reacted with chloroacetic acid affording 2-(anthracen-9(10H)-ylidenehydrazono)thiazolidin-4-one 7. The structures of all the products have been determined by elemental analysis and spectral studies. All compounds have been screened for their antibacterial and antifungal studies. The results are summarized in
Journal of Molecular Structure, 2007
This paper presents time resolved laser induced luminescence (LIL) and diffuse reflectance laser ... more This paper presents time resolved laser induced luminescence (LIL) and diffuse reflectance laser flash-photolysis (DRLFP) studies of solid powdered samples of xanthione (XT) and 4H-1-benzopyran-4-thione (BPT). These thioketones form inclusion complexes with p-tert-butylcalix[6]arene (CLX[6]) and p-tert-butylcalix[8]arene (CLX[8]). Room temperature air equilibrated LIL studies for XT/CLX[8] inclusion complex have shown the existence of both fluorescence and delayed fluorescence emission (S2→S0 emissions
Journal of Luminescence, 1994
ABSTRACT
revistadechimie.ro
REV. CHIM. (Bucharest) ♦ 62♦ No. 4 ♦ 2011 http://www.revistadechimie.ro 462 ... A Study of the Th... more REV. CHIM. (Bucharest) ♦ 62♦ No. 4 ♦ 2011 http://www.revistadechimie.ro 462 ... A Study of the Thickness of TiO ... Photocatalytic Decomposition of Soluble Indigo Blue Dye ... ANABELA S. OLIVEIRA1,2*, ENRICO M. SAGGIORO3, NÁDIA R. BARBOSA4 , ANDRÉ MAZZEI5, ...
WIT Transactions on Ecology and the Environment, 2012
ABSTRACT The farming and agro-industrial sector generates large amounts of organic residues which... more ABSTRACT The farming and agro-industrial sector generates large amounts of organic residues which have a high energetic potential and in most cases are not recovered. Various technologies, including those for energy and agricultural applications, have been considered for the economical valorization of these residues. In this work, we show the results of a study on the potential use of some agro-industrial residues produced in the Portuguese Alto-Alentejo region, in particular, coffee husks, and forest and vineyards residues. The study was conducted in a pilot thermal gasification plant, installed at Portalegre’s Industrial Park based on the fluidized bed technology, with a processing capacity of 70 kg/h, and operating at around 800ºC. The gasification tests were performed continuously for several days, using different waste in order to optimize the heat value and composition of produced syngas. A comparative evaluation of the economic viability of the use of this waste as raw material for the commercial production of synthesis gas and synthetic city gas was made. The results achieved allow the conclusion that the waste biomasses studied show interesting features for use as syngas raw material. Keywords: biofuel, pilot plant, gasification, fluidized bed, syngas. 1 Introduction Bioenergy and biofuels are one of the most important alternatives to fuel production to minimize the continuous depletion of fossil fuel resources and the increasing concerns with environmental issues. Organic living matter, or biomass, in energy terms, is no more than a form of chemical storage of solar electromagnetic energy. When the bonds between carbon, hydrogen and oxygen
Waste and Biomass Valorization, 2014
ABSTRACT The wine industry, an important economic activity in Portugal, particularly in the Alto-... more ABSTRACT The wine industry, an important economic activity in Portugal, particularly in the Alto-Alentejo region, generates large amounts of residues, specially, the pruning of the vines. Various technologies, including energy and agricultural applications, have been considered for the economical valorization of these residues. In this work the results of a study on the potential use of vines pruning biomasses as a source for syngas (gasification gas) production by thermal gasification are presented. The study was conducted in a pilot thermal gasification plant, installed at Portalegre’s Industrial Park. The unit is based on fluidized bed technology, with a processing capacity of 70 kg/h, and operates at 800 °C. The gasification tests were performed continuously for several days, using pellets of mixtures with different mass ratios of vine pruning and wood, in order to optimize the heat value and the composition of produced gas and condensate obtained. A thermodynamic model were developed to allow simulation of the biomass gasification process in a fluidized bed gasifier and to anticipate the composition of the produced gas from the biomass elemental analysis and the prevailing operational conditions. Experimental results fit quite well to the used model. Results show that vines pruning biomasses have interesting features for use as gasification gas raw-material.
Journal of Photochemistry and Photobiology A: Chemistry, 2003
The quantum yields for singlet oxygen generation of several squarylium cyanine dyes derived from ... more The quantum yields for singlet oxygen generation of several squarylium cyanine dyes derived from benzothiazole, benzoselenazole and quinoline, displaying absorption within the so-called "phototherapeutic window" (600-1000 nm), were determined, envisioning their potential usefulness for photodynamic therapy (PDT). The determination was performed by a direct method measuring the luminescence decay of the dyes in the near infrared. Considering the absorption and the quantum yields displayed by some of the dyes, these seemed to be potential candidates as sensitizers for PDT.
Journal of Photochemistry and Photobiology A: Chemistry, 2004
Several symmetrical N-methylamino-and N,N-diethylaminosquarylium cyanine dyes bearing benzothiazo... more Several symmetrical N-methylamino-and N,N-diethylaminosquarylium cyanine dyes bearing benzothiazole, benzoselenazole and quinoline nuclei, displaying strong absorption within the "phototherapeutic window" (600-1000 nm), were investigated for the efficiency of singlet oxygen production, aiming their potential sensitising ability for photodynamic therapy (PDT). The assessment was performed determining the corresponding quantum yields of singlet oxygen generation, measuring the luminescence decay of the dyes in the near infrared. By combining the exhibited absorption and the obtained quantum yields, some of the dyes can be regarded as potential candidates as sensitizers for PDT.
WIT Transactions on Ecology and the Environment, 2013
ABSTRACT The presence of emergent pollutants in waters and wastewaters are an issue of increasing... more ABSTRACT The presence of emergent pollutants in waters and wastewaters are an issue of increasing concern due to the risk they pose to human and environmental health. Cancer Photodynamic Therapy photosensitizers and their metabolites and photodegradation products are pharmaceutical substances that after treatment will be eliminated from the human body and will eventually reach water bodies. Porphyrins are well established PDT sensitizers and cyanine dyes are promising candidates for the same use. In that way it is important to know how those compounds degrade once they reach water bodies and to find efficient treatment methodologies in case they are persistent. In this paper the simulated solar light photodegradation of a porphyrin (Zinctetraphenylporphyrin) and of a cyanine dye (3,3´-diethylindocarbocyanine iodide) in water was investigated, in the absence and in the presence of the most used photocatalyst for semiconductor photocatalysis: Titanium dioxide (TiO2). We observed that the porphyrin (1x10-3M) did not undergo photodegradation in the absence of photocatalyst and that in its presence the photodegradation process was strongly promoted (60% photodegradation reached after 1 hour of irradiation with 0,01g of TiO2). The
Journal of the Serbian Chemical Society, 2008
A series of four Zn(II) complexes with asymmetrical porphyrinic ligands were synthesized: [5-(4-h... more A series of four Zn(II) complexes with asymmetrical porphyrinic ligands were synthesized: [5-(4-hydroxyphenyl)-10,15,20-triphenyl-21H,23H-porphinato]Zn(II) (Zn(II)TPPOH P ), [5-(3-hydroxyphenyl)-10,15,20-triphenyl-21H,23H--porphinato]Zn(II) (Zn(II)TPPOH M ), [5-(2-hydroxyphenyl)-10,15,20-triphenyl--21H,23H-Zn(II)-porphinato]Zn(II) (Zn(II)TPPOH O ) and the well-known (5,10,15,20--tetraphenyl-21H,23H-porphinato]Zn(II) (Zn(II)TPP) as reference, in a 1:1 mole ratio. In all cases, the free-base porphyrin served as a tetradentate ligand through the four pyrrole nitrogen atoms. The complexes were characterized by elemental analysis, FTIR and UV-Vis spectroscopy, which fully confirmed the structure of the complexes. UV-Vis showed that the spectral absorption of the four complexes was blue-shifted by at least 50 nm compared to that of the free ligands. Also important structural data were obtained from several different NMR experiments (including 1 H-NMR, 13 C-NMR, DEPT, COSY, HMBC and HMQC). Influences of external substituents on the porphyrin ring were observed.
Molecules (Basel, Switzerland), 2015
In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3... more In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin and Cu(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin were synthesized, and characterized from a spectral and biological point of view. The study provided data concerning the behavior of identical external substituents vs. two different core insertions. Some of the properties of the proposed tetrapyrrolic structures were highlighted, having photodynamic therapy of cancer as a targeted biomedical application. Elemental analysis, NMR, FTIR and UV-Vis data in various solvents were provided. A preliminary in vitro study on normal and cancer cultured cells was carried out for biocompatibility assessment in dark conditions. The preliminary in vitro study performed on human peripheral mononuclear cells exposed to tetrapyrrolic compounds (2 µM) showed that the proposed compounds had a convenient cytotoxic profile on human normal peripheral blo...
Biomedical Engineering - From Theory to Applications, 2011
Toxicology Letters, 2011
It is well known that photosensitizing agents based on porphyrins structures tend to accumulate p... more It is well known that photosensitizing agents based on porphyrins structures tend to accumulate preferentially in tumor cells and less in their normal counterparts. Based on this capacity they were utilized in therapy but their fluorescent properties may be also valuable for imagistic purposes. Our aim was to establish the capacity of some porphyrin families to serve as organelles/cell/tissue markers, thus setting up the cytotoxic outline of these compounds was the first objective of the project. In this view, we have synthesized some novel copper (II) and zinc (II) porphyrinic complexes intended for further development in cellular imagistic procedures. We have evaluated the dark cytotoxicity of the compounds on cell lines (U937) and isolated peripheral blood mononuclear cells (PBMC) from healthy and cancer patients. Several experimental protocols were used for cellular viability and proliferation capacity. Cellular uptake yield and efflux capacity of porphyrins were evaluated by flow-cytometry. Obtained data have proven the non-toxic nature of the novel compounds even at high doses. Furthermore, the best cellular uptake was registered after prolonged incubation. Human PBMC data revealed a different pattern of cellular response to the new complexes, suggesting an anti-tumoral action upon PBMC isolated from tumor bearing patients. Data gathered by confocal microscopy suggested that these compounds can be good candidates for cellular markers, especially in the case of normal PBMC cells. Further data will pin-point the exact intracellular compartment and the accurate tracker capacity of these fluorescent probes.
Photochemical & Photobiological Sciences, 2006
Diffuse reflectance and luminescence techniques were used to study the photophysics and photochem... more Diffuse reflectance and luminescence techniques were used to study the photophysics and photochemistry of pyrene within p-tert-butylcalix [n]arenes with n = 4, 6, and 8, and to study their ability to form inclusion complexes in heterogeneous media. Evidences for inclusion complex formation were found for the three hosts under study. Ground state diffuse reflectance results have shown the formation of ground state dimers of pyrene inside the cavity of calix[6]arene and calix[8]arene, with this feature much more evident for calix arene. For calix[4]arene, only a monomer fits inside the cavity and the presence of pyrene microcrystals outside the cavity was detected. A luminescence lifetime distribution analysis was performed, revealing the presence of prompt emissions from the pyrene microcrystals outside the cavity in the case of calix[4]arene and from the constrained dimers inside the cavities of calix[6]arene and calix[8]arene. Transient absorption results have shown the presence of pyrene radical cation and also of trapped electrons for the three hosts under study. The formation of the phenoxyl radical of the calixarene following the laser pulsed excitation of pyrene at 355 nm is increased for calix[6]arene and calix arene. This feature is particularly relevant for calix[6]arene, suggesting a very favourable situation for the hydrogen atom abstraction to occur. The analysis of the degradation products revealed the presence of hydroxypyrene as a major photodegradation product for the three hosts. Dihydro-hydroxypyrene was also formed in the case of calix[6]arene and calix[8]arene. The formation of the calixarene's phenoxyl radical and subsequent hydrogen abstraction is consistent with the formation of dihydro-dihydroxypyrene.
Molecules, 2010
Cu(II) complexes with asymmetrical and symmetrical porphyrinic ligands were synthesized with supe... more Cu(II) complexes with asymmetrical and symmetrical porphyrinic ligands were synthesized with superior yields using microwave irradiation. The paper presents the synthesis of 5-(3-hydroxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl)-21,23-Cu(II)porphine in comparison to its symmetrical complex 5,10,15,20-meso-tetrakis-(4-carboxymethylphenyl)-21,23-Cu(II) porphine. The two compounds were characterized by FT-IR, UV-Vis and EPR spectroscopy, which fully confirmed the structures. The spectral molecular absorption properties of the porphyrinic complexes were studied in organic solvents (methanol, ethanol, iso-propanol, dimethyl sulfoxide, dimethylformamide and methylene chloride), and the influence of the solvent polarity on the absorbance maxima is described. In order to establish their future potential in biomedical applications preliminary toxicological studies consisting of viability and proliferation of standard tumor cell lines
Macromolecules, 1998
Rhodamine B isothiocyanate was adsorbed onto microcrystalline cellulose by two different methods:... more Rhodamine B isothiocyanate was adsorbed onto microcrystalline cellulose by two different methods: deposition from ethanolic and aqueous solutions followed by solvent evaporation and also from aqueous solutions in equilibrium with the powdered solid and following a dyeing protocol. After the above-mentioned samples were carefully washed, the fluorescence quantum yields (φ F) determined were about 0.40 ( 0.03 and 0.28 ( 0.03 for ethanol and water, respectively, solvents that efficiently swell cellulose, when these two solvents were used for sample preparation with the first method, while for dyed samples φF is only 0.10 ( 0.05. These values for φF can be compared with 0.70 ( 0.03 obtained for rhodamine B entrapped in the polymer chains of microcrystalline cellulose. X-ray photoelectron spectroscopic studies present evidence for a smaller positive charge density on the nitrogen atom for dyed samples when compared with the adsorbed ones. This is compatible with nitrogen atoms, which do not participate in the conjugated system. These findings indicate that rhodamine B has different conformers in dyed samples as compared to adsorbed samples. In the former case, the chemical bond, anchoring the dye to microcrystalline cellulose, leads to nonplanar conformers with smaller φ F and fluorescence lifetime (τF) values. In the latter case, planar conformers predominate, with the consequent increase of both lifetime and fluorescent quantum yield.
Langmuir, 1997
1,1′-Diethyl-2,2′-cyanine iodide and 1,1′-diethyl-2,2′-carbocyanine iodide were adsorbed onto mic... more 1,1′-Diethyl-2,2′-cyanine iodide and 1,1′-diethyl-2,2′-carbocyanine iodide were adsorbed onto microcrystalline cellulose by two different methods: by deposition from ethanolic solutions, followed by solvent evaporation, and also from ethanolic solutions in equilibrium with the powdered solid. Within experimental error, both methods provided the same fluorescence quantum yield of the adsorbed dyes in the concentration range 0.01-5.0 µmol of dye per gram of cellulose. Ethanol swells cellulose and some dye molecules become entrapped within the natural polymer chains and in close contact with the substrate. The use of dichloromethane, a solvent which does not swell microcrystalline cellulose, provides samples which exhibit a smaller fluorescence quantum yield. This is consistent with a larger degree of mobility (and also the formation of nonplanar and less emissive conformers) of the cyanines adsorbed on the surface of the solid substrate, while entrapment provides more rigid, planar, and emissive fluorophers. At the same time, the adsorption isotherms of 2,2′-cyanine on cellulose from alcoholic and dichloromethane solutions show that the specific cellulose surface area accessible for dye adsorption is larger when adsorption is from ethanol rather than from dichloromethane. For 2,2′-cyanine the fluorescence quantum yields (Φ F) determined were about 0.08 when dichloromethane (a solvent which does not swell cellulose) was used for sample preparation, while with ethanol ΦF was approximately 0.30. These values are about 3 orders of magnitude higher than those in solution, showing the importance of the rigid dry matrix in reducing the nonradiative pathways of deactivation of the (π, π*) first excited singlet state of this cyanine. X-ray photoelectron spectroscopic studies present evidence for hydrogen bonding of 2,2′-cyanine to cellulose at low loadings and for the formation of aggregates at higher loadings adsorbing from both ethanol and dichloromethane. This hydrogen bonding is assigned as involving dye molecules entrapped within the cellulose chains. On the other hand, for 2,2′-carbocyanine, evidence exists for an increase of hydrogen bonding with dye loading. This result together with evidence from ground-state diffuse reflectance absorption and luminescence is compatible with dye molecules being firmly bonded to the substrate by one of the nitrogen atoms, with the other unbound.
Journal of King Saud University - Science, 2011
The reaction of anthrone 1 with 4-aminoantipyrine and thiosemicarbazide afforded 4-(anthracen-9(1... more The reaction of anthrone 1 with 4-aminoantipyrine and thiosemicarbazide afforded 4-(anthracen-9(10H)-ylideneamino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one 2 and anthracen-9(10H)-one thiosemicarbazone 5, respectively. Oxidation of compound 2 with potassium permanganate gave 4-(anthracen-9(10H)-ylideneamino)-1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H pyrazole-5-carboxylic acid 3 which on reaction with o-phenylenediamine gave 4-(anthracen-9(10H)-ylideneamino)-5-(1H-benzimidazol-2-yl)-1-methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one 4. Furthermore, compound 5 was condensed with different substituted phenacyl bromide to give a series of 2-(anthracen-9(10H)-ylidenehydrazono)-5-substituted-2,3-dihydro-1H-thiazole 6a-g. Compound 5 also reacted with chloroacetic acid affording 2-(anthracen-9(10H)-ylidenehydrazono)thiazolidin-4-one 7. The structures of all the products have been determined by elemental analysis and spectral studies. All compounds have been screened for their antibacterial and antifungal studies. The results are summarized in
Journal of Molecular Structure, 2007
This paper presents time resolved laser induced luminescence (LIL) and diffuse reflectance laser ... more This paper presents time resolved laser induced luminescence (LIL) and diffuse reflectance laser flash-photolysis (DRLFP) studies of solid powdered samples of xanthione (XT) and 4H-1-benzopyran-4-thione (BPT). These thioketones form inclusion complexes with p-tert-butylcalix[6]arene (CLX[6]) and p-tert-butylcalix[8]arene (CLX[8]). Room temperature air equilibrated LIL studies for XT/CLX[8] inclusion complex have shown the existence of both fluorescence and delayed fluorescence emission (S2→S0 emissions