The synthetic versatility and the potential applications of porphyrins and analogues in different fields have aroused special interest in their study, especially to mimic biological systems, such as cytochrome P-450. The ability of the porphyrin tetrapyrrolic core to accommodate metal ions of varying charges can modulate the type of application of these compounds. As a contribution, in this special number in honor to the Brazilian women who have devoted their lives to the growth and dissemination of chemistry knowledge, we report the advances in porphyrin research in Brazil for catalytic purposes and other applications, beginning at the Universidade de São Paulo (USP) at Ribeirão Preto. We also discuss some works that have resulted from joint research effort between Brazilian researchers and Portuguese colleagues from the Universidade de Aveiro, Portugal, working in the porphyrin field.

Monensin A is an important commercially available natural product isolated from Streptomyces cinnamonensins that shows antibiotic and anti-parasitic activities. This molecule has a significant influence in the antibiotic market, but until now there are no studies on putative metabolite formations. Bioorganic catalysts applying metalloporphyrins and mono-oxygen donors are able to mimic the cytochrome P450 reactions. This model has been employed for natural product metabolism studies affording several new putative metabolites and in vivo experiments confirming the relevance of this procedure. In this work we evaluated the potential of 10,15,20-tetrakis (pentafluorophenyl) porphyrin metal(III) chloride [Fe(TFPP)Cl] catalyst models to afford a putative monensin A metabolite. Oxidation agents such as meta-chloroperoxy benzoic acid, iodosylbenzene, hydrogen peroxide 30 wt.% and tert-butyl hydroperoxide 70 wt.%, were used to investigate different reaction conditions, in addition to the analysis of the influence of the solvent. The quantification of total monensin A conversion and the structure of the new hydroxylated putative metabolite were proposed based on electrospray ionization tandem mass spectrometry analysis. The porphyrin tested, afforded moderate conversions of monensin A in all reaction conditions and the selectivity was found to be dependent on the oxidation/medium employed.

This work describes a simple and economical experiment for the extraction and purification of chlorophyll a from Spirulina maxima. Extraction and purification of natural compounds can be considered one of the most illustrative experiments that can be performed in Organic Chemistry courses. Particularly, the chromatography of dyes and pigments allows students to have a better comprehension of the chromatography separations. These compounds represent an important class of organic pigments applied in pharmaceutical, cosmetic, detergent compositions, and various other fields and can be extracted from plants and algae. To extract, separate and purify chlorophyll a from associated pigments such as xanthophylls, carotenes, and pheophytins, very costly processes are reported. The present approach is perfectly adequate for use in Chemistry experiments for undergraduate students.

Neste trabalho estudamos a epoxidação do cicloocteno com PhIO utilizando uma nova porfirina 5,10,15,20-tetraquis(2-hidroxi-5-nitrofenil)porfirinato de ferro(III), suportada em matrizes de sílica via interação eletrostática e / ou ligações covalentes, como catalisador. Estes catalisadores foram obtidos e imobilizados em suporte sólido (sílica propiltrimetilamônio (SiN+); sílica propiltrimetilamônio e propilimidazol [SiN+(IPG)] e cloropropilsílica (CPS)) via interações eletrostáticas e ligações covalentes. A caracterização do catalisador suportado por UV-Vis e EPR (ressonância eletrônica paramagnética) indicou a presença de uma mistura de espécies de FeII e FeIII em todos os catalisadores obtidos. No caso da epoxidação do (Z)-cicloocteno por PhIO, os rendimentos observados para o cis-epoxiciclooctano foram satisfatórios para as reações catalisadas pelos três materiais (entre 65 e 85%). Estes resultados indicam que a imobilização de metaloporfirinas em suportes sólidos via grupos localizados na posição orto de seus anéis mesofenil pode promover a catálise eficiente das reações de epoxidação. O catalisador 1-CPS é menos ativo que 1-SiN e 1-SiN(IPG), o que está em acordo com a imobilização destas metaloporfirinas em suportes sólidos via interações eletrostáticas, o que é mais fácil de ocorrer e resulta em um catalisador mais ativo. A atividade do catalisador suportado permaneceu a inalterada, mesmo após três reciclos sucessivos, mostrando que eles são estáveis sob condições oxidantes.

In this work we have studied cyclooctene epoxidation with PhIO, using a new iron porphyrin, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrinato iron(III), supported on silica matrices via eletrostatic interaction and / or covalent bonds as catalyst. These catalysts were obtained and immobilized on the solid supports propyltrimethylammonium silica (SiN+); propyltrimethylammonium and propylimidazole silica [SiN+(IPG)] and chloropropylsilica (CPS) via elestrostatic interactions and covalent binding. Characterization of the supported catalysts by UV-Vis spectroscopy and EPR (Electron paramagnetic resonance) indicated the presence of a mixture of FeII and FeIII species in all of the three obtained catalysts. In the case of (Z)-cyclooctene epoxidation by PhIO the yields observed for cis-epoxycyclooctane were satisfactory for the reactions catalyzed by the three materials (ranging from 68% to 85%). Such results indicate that immobilization of metalloporphyrins onto solid supports via groups localized on the ortho positions of their mesophenyl rings can lead to efficient catalysts for epoxidation reactions. The catalyst 1-CPS is less active than 1-SiN and 1-SiN(IPG), this argues in favour of the immobilization of this metalloporphyrin onto solids via electrostatic interactions, which is easier to achieve and results in more active oxidation catalysts. Interestingly, the activity of the supported catalysts remained the same even after three successive recyclings; therefore, they are stable under the oxidizing conditions.

This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

In recent years, because of the need for a more flexible curriculum established by the Curriculum Guidelines of the National Brazilian Education (law 9394/96), the pedagogical project of the Chemistry course of FFCLRP/USP has undergone alterations, amongst them the gradual reduction of the hours devoted to the discipline Qualitative Analytical Chemistry. In this context, this discipline has been carefully analyzed and reorganized in order to allow the elimination of redundancies and the introduction of activities considered important for the professional formation of both chemists and chemistry teachers. In this work, we will discuss the main strategies adopted in this reorganization with the objective of making the teaching/learning process more dynamic and efficient.

A terapia fotodinâmica (TFD) está baseada na administração e no acúmulo de fotossensibilizador, por exemplo, de tipo porfirina ou clorina, em tecidos doentes. As clorinas apresentam propriedades fotofísicas semelhantes àquelas das porfirinas, mas com intensificação e deslocamento das bandas Q, o que faz com que sejam bons candidatos para TFD. Neste trabalho relata-se a síntese da 5,10,15-tris(pentafluorofenil)-20-(4-piridil)porfirina, (2), e das clorinas isômeras 4, (5,10,20-tris(pentafluorofenil)-15-(4-piridil)-tetra-hidro-1H- N-metil-pirrolo[3,4-b]porfirina e 5, (5,10,15-tris(pentafluorofenil)-20-(4-piridil)-tetra-hidro-1H- N-metil-pirrolo[3,4-b]porfirina, obtidas a partir de 2, por reação de cicloadição 1,3-dipolar com um ileto azometínico, e respectivas caracterizações estruturais por UV-Vis, RMN e EM-FAB. Foram avaliadas as propriedades fotofísicas, fotoquímicas e fotodegradativas para a nova clorina 4, obtida com melhor rendimento que o seu isômero 5. O rendimento quântico de fotodegradação (fiFd, mol Einstein-1) foi de 0,047±0,014. Foram ainda realizados testes com ácido úrico para demonstrar a capacidade do fotossensibilizador na produção de ¹O2. Os resultados mostraram que a nova clorina 4 pode ser considerada como um bom fotossensibilizador para TFD.

Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorin, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorin-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorin derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, ¹H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorin 4 have been evaluated. Its quantum yield of photobleaching (phiPb, mol Einstein-1) was 0.047±0.014. In order to demonstrate the production of ¹O2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorin 4 can be considered a promising photosensitizer in PDT.

As hidroxinitrofenilporfirinas, 5,10,15,20-tetrakis(2-hidroxi-5-nitrofenil)porfirina e 5-mono(carboxifenil)-10,15,20-tris(2-hidroxi-5-nitrofenil)porfirina , estudadas neste trabalho, foram preparadas pelo método de Adler e caracterizadas por ¹H RMN e por espectroscopia de absorção e emissão na região espectral visível. A formação de ¹O2 foi constatada através do teste do ácido úrico (AU), o qual consiste na observação do decréscimo na absorbância da banda do AU em 293 nm, após irradiação da solução, com laser, contendo o fotossenssibilizador e o AU. Os resultado obtidos indicaram que as hidroxinitrofenilporfirinas podem ser consideradas potenciais fotossensibilizadores para terapia fotodinâmica.

The hydroxynitrophenylporphyrins, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrin and 5-mono(carboxyphenyl)-10,15,20-tris(2-hydroxy-5-nitrophenyl)porphyrin described in this work were prepared through Adler's method. These compounds were characterized by ¹H NMR and light absorption and emission spectroscopy in the visible region. In order to demonstrate the involvement of ¹O2 production, the uric (UA) acid test was carried out, which considers the decrease in the absorbance of UA at 293 nm following laser light irradiation of a solution containing UA and a photosensitizer. The results obtained demonstrate that these hydroxynitrophenylporphyrins can be considered as promising photosensitizers in PDT.

The toxic heavy metals can not be transformed in other less toxic substances as organic wastes through chemical process. Various chemistry courses at Faculty of Philosophy, Sciences and Humanities (FFCLRP/USP) use heavy metals in their experimental classes. In this context, a course were created: "Heavy Metal Wastes generated in the teaching and research laboratories: disposal or recovery" and has a specific goal to capacitate the students to define the adequate strategy for disposal or recovery of the chemical wastes, in particular heavy metals, through an interdisciplinary approaching. This course was given to 25 students during the second semester of 2000 and 2001. The environmental responsibility desired for the professional and citizen can be promoted.

Neste artigo estamos relatando a aplicação da cromatografia líquida de alta eficiência acoplada à espectrometria de massas (LC-MS-MS) para a identificação dos produtos formados na oxidação de albendazol e disopiramida utilizando metaloporfirinas em dicloroetano como catalisador e iodozilbenzeno como doador de oxigênio. Nossos resultados comprovam que LC-MS-MS é uma poderosa técnica para o estudo in vitro de metabolismo de fármacos, permitindo a identificação de metabólitos conhecidos ou não. Foi observado que o sistema catalítico usado resultou na formação dos mesmos metabólitos obtidos in vivo, embora outros produtos também foram formados na oxidação da disopiramida.

In this paper we report the application of liquid chromatography-mass spectrometry (LC-MS-MS) to the identification of the products formed by oxidation of albendazole and disopyramide with metalloporphyrins in dichloroethane, using iodosylbenzene as an oxygen donor. Our results show that LC-MS-MS is a powerful tool to study the in vitro metabolism of drugs, allowing the identification of known and unknown metabolites. In addition, it was observed that the catalyst system used resulted in the formation of the same metabolites as obtained in vivo, although for disopyramide other products were also observed.

The sol-gel process is a methodology used to obtain organic-inorganic hybrid solids, which open new possibilities in the field of material science. The sol-gel technique offers a low temperature attractive approach for introducing organic molecules into amorphous materials. In order to introduce tetrakis (2-hydroxy-5-nitrophenyl)porphyrin covalently bounded to a silicate matrix, the inorganic precursor 3-isocyanatopropyltriethoxysilane was added (molar ratio 2:1) to the porphyrin solution in anhydrous dimethylformamide and triethylamine. The isolated porphyrin and the hybrid porphyrinosilica have excitation maximum centred at 400 nm and 424 nm, respectively and the emission spectra for both materials has bands centred at 650 nm and 713 nm. The formation of hybrid matrix was investigated by FTIR.

Muitos compostos modelo contendo porfirinas têm sido preparados num esforço para entender o sistema de fotossíntese e os processos de aproveitamento de energia solar. Sistemas doadores-receptores contendo porfirinas têm sido freqüentemente estudados para testar várias descrições teóricas sobre transferência de elétrons. O estudo de parâmetros fotoquímicos e fotofísicos como a distância para transferência de energia, geometria molecular e a diferença de potencial eletrônico, tem se mostrado importante para a definição da transferência eletrônica em porfirinas. Neste trabalho apresentamos a síntese, purificação e caracterização por espectroscopia UV/Vis, ¹H e 19F RMN, luminescência e tempos de vida de novos modelos moleculares de porfirinas, que permitam investigar esses parâmetros. Utilizou-se o dímero Zn,Mn(TPPF4)2pip e seus monômeros ZnTPPF4pipH e MnF5TPP. A caracterização do ZnMn(TPPF4)2pip, foi dificultada devido a presença de Mn+3, devido ao forte acoplamento dos orbitais dpi do manganês e o sistema pi da porfirina, que aumenta a interação manganês-porfirina mudando o espectro eletrônico UV/Vis e distorcendo os sinais de ¹H e 19F RMN do dímero. A presença de Mn+3 desloca E1/2 do anel porfirínico para valores mais negativos, o que resulta em reduções mais difíceis, impedindo a transferência de energia da Znporfirina para a Mnporfirina.

Porphyrins have revealed that factors as the energy transfer distance, molecular geometry and the difference of electronic potential, are important in a well defined electronic transfer. Porphyrin- containing donor-acceptor systems have been usefully employed to test various theoretical descriptions of electron transfer. The objective of this paper consists on the synthesis, purification and characterization by UV/Vis spectroscopy, ¹H and 19F NMR, luminescence and lifetime of new molecular models, allowing the investigation of energy transfer parameters. This study was accomplished using the dimer Zn,Mn(TPPF4)2pip and its monomers ZnTPPF4pipH and MnF5TPP. The dimer characterization, Zn,Mn(TPPF4)2pip, was difficult due to the presence of Mn3+. The strong overlap between dpi orbitals of manganese and the porphyrin pi system increases the interaction manganese-porphyrin in changing the UV/Vis electronic spectrum and distorting the ¹H and 19F NMR signals of dimer. The presence of Mn3+ shifts the reduction potential of E1/2 of the porphyrin ring to more negatives values, what results in more difficult reductions, disabling the transfer of energy from Zincporphyrin to Manganeseporphyrin.

As porfirinas aniônicas 5,10,15-tris(4-carboxifenil), 20-mono(2-nitrofenil) porfirina (1), 5,10(ou 15)-bis(4-carboxifenil), 15(or 10),20-bis(2-nitrofenil)porfirina (2) and 5-mono(4-carboxifenil), 10,15,20-tris(2-nitrofenil)porfirina (3), foram sintetizadas diretamente através da reação de pirrol com os benzaldeídos substituídos em meio de ácido propiônico/nitrobenzeno. A relação molar dos benzaldeídos foi controlada para otimizar a síntese e purificação das porfirinas desejadas. Esta nova série de porfirinas foi caracterizada por cromatografia em camada delgada, espectrometria de massas (FAB MS), RMN ¹H, UV/Vis, IV e eletroquímica. As porfirinas 5,10,15,20-tetrakis(4-carboxifenil)porfirina (4) e 5,10,15,20-tetrakis(2-nitrofenil)porfirina (5) também foram estudadas para comparação, tornando a série completa. A redução eletroquímica das porfirinas base livre e correspondentes ferro(III) porfirinas foi investigada em eletrodos de carbono e mercúrio. Os potenciais de redução mostraram a dependência esperada do número de grupos nitro, fortemente retirador de elétrons, presentes no anel porfirínico, fornecendo evidências adicionais para a caracterização dos compostos sintetizados.

The anionic 5,10,15-tris(4-carboxyphenyl), 20-mono(2-nitrophenyl) porphyrin (1), 5,10(or 15)-bis(4-carboxyphenyl), 15(or 10),20-bis(2-nitrophenyl)porphyrin (2) and 5-mono(4-carboxyphenyl), 10,15,20-tris(2-nitrophenyl)porphyrin (3) were sinthesized directly by reaction of pyrrole with substituted benzaldehydes in nitrobenzene/propionic acid media. The benzaldehydes molar ratio was controlled to optimize the synthesis and purification of the desired porphyrins. This new series of porphyrins was characterised by TLC, mass spectrometry (FAB MS), ¹H NMR, UV/Vis, IR and electrochemistry. 5,10,15,20-Tetrakis(4-carboxyphenyl)porphyrin (4) and 5,10,15,20-Tetrakis(2-nitrophenyl)porphyrin (5) were also characterised for comparative purposes, completing the series The electrochemical reduction was investigated for the free base and corresponding iron(III) porphyrins on glassy carbon and mercury electrodes. The reduction potentials showed the expected dependence on the number of electron-withdrawing nitro groups present on the porphyrin ring providing additional evidences for the characterisation of the synthesised compounds.

New materials porphyrinosilica and metalloporphyrinosilica template have been obtained by a sol-gel processing where functionalyzed porphyrins and metalloporphyrins "building blocks" were assembled into a three-dimensional silicate network. The optimized conditions for preparation of these materials are revised. The monomer precursors porphyrinopropylsilyl and metalloporphyrinopropylsilyl preparation reactions and subsequent one pot sol-gel processing with tetraethoxysilane are discussed. In the case of metalloporphyrins the nitrogen base coordinates to the central metal and acts as a template in the molecular imprinting technique. UV-visible absorption spectroscopy, thermogravimetric analysis, electron paramagnetic resonance, nuclear magnetic spectra, infrared spectra, luminescence spectra, surface area and electron spectroscopy imaging of the materials are used to characterize the prepared materials. The catalytic activities of these metalloporphyrinosilica- template are compared.

In this work we report the obtention of a tetrabutylammonium hydroxide (TBAOH) solution in acetonitrile in a one pot process in order to study the interaction ironporphyrinOH- in non-aqueous systems. All the reactions were carried out under dry argon atmosphere to prevent the contamination of the solution with CO2, which leads to the formation of (TBA)2CO3.