Anabela Sousa Oliveira

Avaliação da contaminação humana por hidrocarbonetos policíclicos aromáticos (HPAs) e seus derivados nitrados (NHPAs): uma revisão metodológica

Polycyclic aromatic hydrocabons (PAHs) and their nitroderivatives (NPAHs) are ubiquitous in the environment and they are produced in several industrial and combustion processes. Some of these compounds are potent carcinogens/mutagens and their determination in biological samples is an important step for exposure control. A review of the analytical methodologies used for the determination of PAHs and their metabolites in biological samples is presented.

Novel laser-induced luminescence resulting from benzophenone/O-propylated p-tert-butylcalix[4]arene complexes. A diffuse reflectance study

Laser-induced room temperature luminescence of air-equilibrated benzophenone/O-propylated p-tert-butylcalix[4]arene solid powdered samples revealed the existence of a novel emission, in contrast with benzophenone/p-tert-butylcalix[4]arene complexes, where only benzophenone emits. This novel emission was identified as phosphorescence of 1-phenyl-1,2-propanedione, which is formed as the result of an hydrogen atom abstraction reaction of the triplet excited benzophenone from the propoxy substituents of the calixarene. Room temperature phosphorescence was obtained in air-equilibrated samples in all propylated hosts. The decay times of the benzophenone emission vary greatly with the degree of propylation, the shortest lifetimes being obtained in the tri- and tetrapropylated calixarenes. Triplet-triplet absorption of benzophenone was detected in all cases, and is the predominant absorption in the p-tert-butylcalix[4]arene case. where an endo-calix complex is formed. Benzophenone ketyl radical formation occurs with the O-propylated p-tert-butylcalix[4]arenes hosts, suggesting a different type of host/guest molecular arrangement. Diffuse reflectance laser flash photolysis and gas chromatography-mass spectrometry techniques provided complementary information, the former about transient species and the latter regarding the final products formed after light absorption. Product analysis and identification clearly show that the two main degradation photoproducts following laser excitation in the propylated substrates are 1-phenyl-1,2-propanedione and 2-hydroxybenzophenone, although several other minor photodegradation products were identified. A detailed mechanistic analysis is proposed. While the solution photochemistry of benzophenone is dominated by the hydrogen abstraction reaction from suitable hydrogen donors, in these solid powdered samples, the alpha-cleavage reaction also plays an important role. This finding occurs even with one single laser pulse which lasts only a few nanoseconds, and is apparently related to the fact that scattered radiation exists, due to multiple internal reflections possibly trapping light within non-absorbing microcrystals in the sample, and is detected until at least 20 micros after the laser pulse. This could explain how photoproducts thus formed could also be excited with only one laser pulse.

Microwave Synthesis, Basic Spectral and Biological Evaluation of Some Copper (II) Mesoporphyrinic Complexes

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-carboxy-methylphenyl)-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 (MCF7 and B16) testing was performed. The obtained results indicate a low toxicity for both compounds and further recommends them for testing in light activation protocols.

Photophysics of oxacyanine dyes on surfaces. Re-examination of the origins of the ‘new emission’ observed with laser excitation and high concentrations of adsorbed dyes

Two oxacarbocyanine dyes, 3,3′-diethyloxacarbocyanine iodide (DOCI) and 3,3′-diethyloxadicarbocyanine iodide (DODCI), have been investigated spectroscopically when adsorbed on microcrystalline cellulose at a range of concentrations from 0.005 to 25 µmol g–1. DOCI shows both H and J aggregation in its ground-state absorption spectrum, while DODCI shows only H aggregation. The degree of aggregation is dependent on the degree of hydration of the samples, decreasing with decreasing hydration. Steady-state emission spectra show the normal ground-state emission, distorted at higher concentrations by absorption by aggregated dye molecules. Laser-excited fluorescence spectra for DOCI show no new features, but for DODCI at higher concentrations and laser fluences a second emission band is observed which shows a square dependence on laser fluence. A similar band can be excited in solution and shows very similar behaviour and is assigned, on this basis, as arising from an emissive photoisomer.

Surface photochemistry: Photodegradation study of pyrene adsorbed onto microcrystalline cellulose and silica

Ground-state diffuse reflectance, time resolved laser-induced luminescence, diffuse reflectance laser flash-photolysis transient absorption and chromatographic techniques were used to elucidate the pho- todegradation processes of pyrene adsorbed onto microcrystalline cellulose and silica. Ground-state diffuse reflectance showed that on both substrates low concentrations display absorption of pyrene monomers. At high concentrations spectral changes attributed to aggregate formation were observed. Laser induced fluo- rescence showed that pyrene onto microcrystalline cellulose mainly presents fluorescence from monomers, while for silica, excimer-like emission was observed from low surface loadings (≥ 0.5 µmol g −1 ). Transient absorption and photodegradation studies were performed at concentrations where mainly monomers exist. On silica, pyrene presents transient absorption from its radical cation. On microcrystalline cellulose both radical cation, radical anion and pyrene triplet-triplet absorption were detected. Irradiation followed by chro- matographic analysis showed that pyrene decomposes on both substrates. For pyrene on microcrystalline cellulose 1-hydroxypyrene was the main identified photoproduct since in the absence of oxygen further ox- idation of 1-hydroxypyrene was very slow. For pyrene on silica photodegradation was very efficient. Almost no 1-hydroxypyrene was detected since in the presence of oxygen it is quickly oxidized to other photooxida- tion products. On both substrates, pyrene radical cation is the intermediate leading to photoproducts and oxygen it is not involved in its formation.

Solar CPC Pilot Plant Photocatalytic Degradation of Indigo Carmine Dye in Waters and Wastewaters Using Supported-TiO2: Influence of Photodegradation Parameters

The photocatalytic degradation of indigo carmine (IC) dye in the presence of titanium dioxide under different conditions was reported. Several factors which interfere with the photodegradation efficiency as catalyst concentration, pH, initial concentration of dye, presence of inorganic anions, temperature, and the addition of hydrogen peroxide were studied under artificial irradiation with a 125 W mercury vapor lamp. Additionally, the catalyst supported on glass spheres was used for the photocatalytic degradation of the dye present in several types of waters in a CPC solar pilot plant. The photocatalytic products, carboxylic acids, and and were followed during IC mineralization. Formate, acetate, and oxalate were detected in real MWWTP secondary effluent. The mineralization efficiency was of 42 and 21% using in suspension and supported TiO2, respectively. In order to evaluate biological effects, Eisenia andrei earthworms were used as a model organism. No significant difference () of weight was observed in the earthworm submitted to different concentrations of IC and its photoproducts. The photocatalytic degradation of IC on TiO2 supported on glass spheres suffered strong influence of the water matrix; nevertheless the method has the enormous advantage that it eliminates the need for the final catalyst removal step, reducing therefore the cost of treatment.

A Singlet Oxygen Photogeneration and Luminescence Study of Unsymmetrically Substituted Mesoporphyrinic Compounds

This paper deals with a series of new unsymmetrically substituted mesoporphyrins: 5-(2-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPO), 5-(3-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPO), 5-(4-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPO), 5-(2-hydroxyphenyl)-10,15,20-tris-butyl-21,23-H-porphyrin (TBPO), and their parent nonsubstituted compounds, respectively, 5,10,15,20-tetrakis-phenyl-21,23-H-porphyrin (TPP) and 5,10,15,20-tetrakis-butyl-21,23-H-porphyrin (TBP). Several photophysical studies were carried out to access the influence of the unsymmetrical substitution at the porphyrinic macrocycle on porthyrins photophysical properties, especially porthyrins efficiency as singlet oxygen sensitizers. The quantum yields of singlet oxygen generation were determined in benzene ((TPP) = 0.66 0.05; (TPPO) = 0.69 0.04; (TPPO) = 0.62 0.04; (TPPO) = 0.73 0.03; (TBP) = 0.76 0.03; (TBPO) = 0.73 0.02) using the 5,10,15,20-tetraphenyl-21,23-H-porphine ((TPP) = 0.66) and Phenazine ((Phz) = 0.83) as reference compounds. Their fluorescence quantum yields were found to be ((TPPO) = 0.10 0.04; (TPPO) = 0.09 0.03; (TPPO) = 0.13 0.02; (TBP) = 0.08 0.03 and (TBPO) = 0.08 0.02 using 5,10,15,20-tetraphenyl-21,23-H-porphine as reference (TPP) = 0.13). Singlet state lifetimes were also determined in the same solvent. All the porphyrins presented very similar fluorescence lifetimes (mean values of (with , air equilibrated) = 9.6 0.3 nanoseconds and (without , argon purged) = 10.1 0.6 nanoseconds, resp.). The phosphorescence emission was found to be negligible for this series of unsymmetrically substituted mesoporphyrins, but an E-type, thermally activated, delayed fluorescence process was proved to occur at room temperature.

Solar Photochemistry for Environmental Remediation - Advanced Oxidation Processes for Industrial Wastewater Treatment

Anabela Sousa Oliveira1,2, Enrico Mendes Saggioro3, Thelma Pavesi3, Josino Costa Moreira3 and Luis Filipe Vieira Ferreira1 1Centro de Quimica-Fisica Molecular and Institute of Nanosciences and Nanotechnology, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Lisboa, 2Centro Interdisciplinar de Investigacao e Inovacao, Escola Superior de Tecnologia e Gestao, Instituto Politecnico de Portalegre, Portalegre, 3Centro de Estudos da Saude do Trabalhador e Ecologia Humana, Escola Nacional de Saude Publica, Fundacao Oswaldo Cruz, Rio de Janeiro, 1,2Portugal 3Brazil

Synthesis and Spectral Evaluation of Some Unsymmetrical Mesoporphyrinic Complexes

Synthesis and spectral evaluation of new zinc and copper unsymmetrical mesoporphyrinic complexes are reported. Zn(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Zn(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Cu(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin and Cu(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin were synthesized using microwave-assisted synthesis. The complexes were characterized by elemental analysis, FT-IR, UV-Vis, EPR and NMR spectroscopy, which fully confirmed their structure. The spectral absorption properties of the porphyrinic complexes were studied in solvents with different polarities. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for the compounds under study, revealing high yields for the zinc derivatives. The copper complexes are not emissive and only display residual capacity for singlet oxygen formation.

Photodegradation of 1-nitropyrene in solution and in the adsorbed state

The photodegradation of the 1-nitropyrene (NPy) has been studied using conventional (Xe and medium pressure Hg lamps) and laser sources (XeCl excimer and Nd-YAG UV). Low energy monochromatic light sources were used to study the early stages of degradation (up to 50% conversion). The medium pressure Hg lamp was used for longer periods of irradiation (up to 6h) and for greater degradation of NPy. The results of our work confirm that degradation occurs by radical mechanism. Aromatic hydroxymethyl, methoxy, hydroxy and nitroso derivatives of pyrene (Py) are created by low energy UV irradiation. After a massive UV irradiation, the Py aromatic system is destroyed and more polar low-molecular compounds are generated. The photochemical method described in this paper, based on irradiation by UV lamp, is therefore, suitable for degradation of fused benzene ring(s) and thus should also be effective for degradation of other nitrated polycyclic aromatic compounds.