31 results on '"Annelise Casellato"'
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2. Estudo espectroscópico de compósito obtido da reação no estado sólido entre um complexo mononuclear de vanádio(IV) e caulinita
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Edivaltris I. P. De Rezende, Antonio S. Mangrich, Ana P. Mangoni, Marciela Scarpellini, Annelise Casellato, and Tatiana L. Fernández
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composite ,EPR spectroscopy ,DRUV-VIS ,Chemistry ,QD1-999 - Abstract
The use of probes, such as paramagnetic species diluted in diamagnetic materials in EPR spectroscopy, and mathematical tools such, as the Kubelka-Munk function in DRUV-VIS spectroscopy are strategies in the analysis of complex mixtures of solid materials. The results obtained here show that the solid state reaction between the complex, [VO(acac)(BMIMAPY)] [ClO4], BMIMAPY = [(bis(1-methylimidazole-2-yl)methyl)(2-(pyridyl-2-yl)ethyl) amine] and acac = acetilacetonate, with kaolinite turns possible to obtain anisotropic EPR spectrum of the complex with a reasonable level of resolution. The study by DRUV-VIS using the method of second derivative mode of the Kubelka-Munk function revealed new complex structural arrangements, a solid hitherto unknown.
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- 2012
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3. Copper(II) Schiff Base Complex with Electrocatalytic Activity Towards the Oxygen Reduction Reaction and Its Catalase Activity
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Thaís Petizero Dionízio, Aline Cantuares dos Santos, Fagner da Silva Moura, Felipe Pereira da Silva, Eliane D’Elia, Annelise Casellato, Francisco Manoel dos Santos Garrido, and Marta Eloisa Medeiros
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Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,Chronoamperometry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,Electrochemistry ,01 natural sciences ,Copper ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Cyclic voltammetry ,0210 nano-technology ,Hydrogen peroxide ,Platinum - Abstract
The fuel cell is a continuously operating, low environmental impact, highly energy-efficient electrochemical device that has been cited as a clean energy source to replace fossil fuels. However, noble metals, such as platinum, are used as electrocatalysts to improve reaction kinetics, which raises the cost of this renewable energy source. This work aimed to evaluate a graphite paste electrode, modified with a copper(II) coordination compound containing N,O-donor groups, as an electrocatalyst in oxygen reduction reactions (ORR) and its catalase-like activity. Through electrochemical analyses, such as cyclic voltammetry and chronoamperometry, the modified electrode activity was investigated at different pH values and scan rates. Catalase activity was also investigated at different pH values in order to establish which would be the most active. The modified electrode proved to be a promising electrocatalyst in ORR in alkaline medium, and the copper(II) complex actively degraded hydrogen peroxide under alkaline conditions, which can help to increase the lifetime of the fuel cell device.
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- 2021
4. A Diversidade de Debates na Pesquisa em Química
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Ranieri Campos, Rafael Vasconcelos Oliveira, Aurileide Maria Bispo Frazão Soares, Bruna Médice Chinelate, Luana Da Silva Flores, Luciano Soares Dos Santos, Raphael De Farias Tavares, Adriana De Lima Mendonça, Tiago Linus Silva Coelho, Lorena Mota Rebouças, Jéssica De Lima Santos, Iago Santos Mesquita, Marluce Oliveira Da Guarda Souza, Raimunda Alves Melo, Samuel De Macêdo Rocha, Adeilton Pereira Maciel, Jose De Arimateia Rodrigues Do Rego, Stefanie Figueira Melo Marinho, Sebastião Gomes Silva, Laise Nayra Dos Santos Pereira, Carlos Cézar Da Silva, José Alves Dias, Mayla Eduarda Rosa Celorio, Darlisson Slag Neri Silva, Nicolle Ribeiro Uchoa, Caroline Oliveira Santos, Cristiane de Araujo da Fonseca, Giovani Pakuszewski, Josiana Moreira Mar, Mariana Bengaly Marques, Victor De Souza Marques, Denise Barros De Almeida Barbosa, Carla Nanci Maia Donola Pereira, Michele Cristiane Diel Rambo, João Marcos Silva Rosendo Dos Santos, Rosana Petinatti Da Cruz, Magale Karine Diel Rambo, Rebeca Moraes Menezes, Felipe Pereira Da Silva, Bruna Layza Moura Vieira, Eliane Flora, Adriana Regina Parmegiani De Oliveira, Marielly Lemes Gonçalves, Isaque Gemaque De Medeiros, Cáritas De Jesus Silva Mendonça, Luan Mateus Da Silva Pinto, Camila Pereira De Lima Chicuta, Sérgio Miguel Planinscheck, Claudinete Dos Santos Silva, Carla Aparecido Da Silva Lopes, Deracilde Santana Da Silva Viégas, Bruna Aparecida De Souza, Cristiane Duarte Alexandrino Tavares, Jardel Meneses Rocha, Ruth Rufino Do Nascimento, Jorddy Neves Da Cruz, Thayssa Ramos Quintialiano Lima, Renato Araújo Da Costa, Karolynne Campos De Morais, Regivaldo Dos Santos Melo, Polyana Morais De Melo, Nathaly Costa De Aquino, Cristina Peitz De Lima, Michelle Maytre Mota Da Costa, Isaide De Araujo Rodrigues, Vitória Valentina Trachinski Carvalho, Nicolle Spricigo, Lucas Alves Da Silva, Cláudio Carneiro Santana Junior, Juracir Francisco De Brito, Pedro Vidinha, Claudia Oliveira Sena, Edivan Carvalho Vieira, Maria Lucia Teixeira Guerra De Mendonça, Ana Lucía Paredes Doig, Eulália Cristina Rodrigues Ficks, Sania Maria De Lima, Tatiana Alves Toledo, Thayná Nunes De Carvalho Fernandes, Sílvia Cláudia Loureiro Dias, Leandro Zatta, Juliana Petinatti Sarmento, Luiz Sidney Longo Júnior, Ana Carolina Moralles Barbosa, Paulo Henrique Bastos Freitas, Uneliton Neves Silva, Camila Peitz, Joana De Jesus De Andrade, Angélica De Brito Sousa, Samuel Henrique Kreis, Abraão Felix Da Penha, Mateus Rodrigues Brito, Rafael Augusto Nobrega Tavares, Jesus Antonio Duarte Gualteros, Micheline Soares Costa Oliveira, Maria Clara Hortencio Clemente, Fernanda Amaral De Siqueira, Roberto Barbosa De Castilho, Alan Sena Pinheiro, Nathan Andryel Bollauf Antunes, Aline Maria Dos Santos Teixeira, Gesley Alex Veloso Martins, Vanessa Da Silva Reis, Joseph Ranei Oliveira Pereira, Thais Petizero Dionízio, Annelise Casellato, Alan Rodrigues Teixeira Machado, Fábio Alberto De Molfetta, Lúcia Schuch Boeira, Tatiani Da Luz Silva, Mikael Kélvin De Albuquerque Mendes, Adriana Clara Da Silva, Fernando Pereira Lima, Yara Karla De Salles Nemet, Ziel Dos Santos Cardoso, Luana Lima Ferreira, Djalma Menezes De Oliveira, Etienne Sampaio Oliveira, Andrezza Da Silva Ramos, Lúcia Pinheiro Santos Pimenta, Renata Costa Zimpeck, Carlos Henrique Cordeiro Castro, Valfredo Azevedo Lemos, Luiza Duarte Rodrigues Da Costa, Thaís Delazare, João Augusto Pereira Da Rocha, Kauani Caldato, Ivan Pollarini Marques De Souza, Isabella Oliveira Da Silva, Milena Belloni Cavalcante Da Silva, Marcos Batista Machado, Juliano Carvalho Ramos, Edmilson Miranda De Moura, Marco Aurélio Suller Garcia, Jaqueline De Araújo Bezerra, Andreza Heloiza Da Silva Gonçalves, Cristine Elizabeth Alvarenga Carneiro, Rafaela Rocha De Paula, Rafael Marangoni, Jacqueline Ribeiro Do Nascimento, Gabriela Trotta Linhares, and Silvia Jaerger
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- 2021
5. SÍNTESE, CARACTERIZAÇÃO E ATIVIDADE ELETROCATALÍTICA FRENTE RRO DE UM NOVO COMPLEXO DE NÍQUEL (II) CONTENDO LIGANTE DO TIPO N,O-DOADOR
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Annelise Casellato, Matheus Maia Diniz, Felipe Pereira da Silva, Marta Eloisa Medeiros, Fagner da Silva Moura, Thaís Petizero Dionízio, and Francisco Manoel dos Santos Garrido
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- 2020
6. Unravelling the Functions of Regulatory T Cells during Infection
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Annelise Casellato, Tania Rahman, and Ferdous Seraj
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Pathogenesis ,Immune system ,Effector ,Immunity ,Tissue damage ,Immunology ,medicine ,hemic and immune systems ,chemical and pharmacologic phenomena ,Inflammation ,Autoimmune responses ,Biology ,medicine.symptom - Abstract
Accumulating evidences have suggested that Treg have an active role in the regulation of immunity to infection. Treg suppress not only autoimmune responses but also other immune responses for instance, during acute infections, against commensal microbes in inflammatory diseases or during chronic illness. Treg have been shown to limit exacerbated inflammation to avoid collateral tissue damage. Treg are also suggested to provide early protective responses in some viral infections as the permitting timely entry of effector cells in infected tissue. Furthermore, Treg have been shown to contribute to form memory pool after resolution of infection. In this review, we survey and analysis our current knowledge and relative dynamics of Treg in a wide range of infection settings and elaborate the examples in which these cells are of critical importance in conferring tolerance, suppressing pathogenesis, inducing protection and optimizing immunity to eliminate infection.
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- 2018
7. Dissecting Emerging Aspects of Regulatory Circuitry in Man and Mice: Regulatory T Cell Biology
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Tania Rahman, Md. Ferdous Seraj, and Annelise Casellato
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Regulatory T cell ,FOXP3 ,chemical and pharmacologic phenomena ,General Medicine ,Biology ,Acquired immune system ,Pathogenesis ,Interleukin 10 ,Immune system ,medicine.anatomical_structure ,Mechanism of action ,Immunity ,Immunology ,medicine ,medicine.symptom - Abstract
Regulatory T cells (Treg), a component of adaptive immunity, are well known for their immunosuppressive roles and their ability to maintain the balance between the immunological and pathological reactions. Treg have been shown to provide protective responses and their depletion has resulted severe pathology in some pathogen infections. The work presented here has unravelled the potential of regulatory cells in the immune system including different repertoir of Treg cell subsets, markers to distinguish them, Treg suppression mechanisms in the pathogenesis of various infections and summarize different mouse models depleting Tregs. These findings would help set up future avenues of research to elucidate a key mechanism of action of these cells and provide new therapeutic insights for pathogenesis and also for broader antibacterial/antiviral/antiproliferative immunity.
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- 2018
8. SÍNTESE, CARACTERIZAÇÃO E ATIVIDADE ELETROCATALÍTICA FRENTE RRO DE UM NOVO COMPLEXO DE NÍQUEL (II) CONTENDO LIGANTE DO TIPO N,O-DOADOR
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Annelise Casellato, Matheus Maia Diniz, Fagner da Silva Moura, Thaís Petizero Dionízio, and Felipe Pereira da Silva
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- 2019
9. COMPLEXOS DE METAIS DE TRANSIÇÃO COMO CATALISADORES PARA A DECOMPOSIÇÃO DE PERÓXIDO DE HIDROGÊNIO (H2O2)
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Fagner da Silva Moura, Felipe Pereira da Silva, Thaís Petizero Dionízio, Annelise Casellato, and Matheus Maia Diniz
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- 2019
10. ATIVIDADE DE CATALASE DE UM NOVO MATERIAL BASEADO EM QUITOSANA E UM COMPLEXO DE COBRE (II)
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Annelise Casellato, Thaís Petizero Dionízio, Felipe Pereira da Silva, Thaís Delazare, Carla Nanci Maia Donola Pereira, and Mariana Bengaly Marques
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- 2019
11. A nickel(II) coordination polymer derived from a tridentate Schiff base ligand with N,O-donor groups: synthesis, crystal structure, spectroscopy, electrochemical behavior and electrocatalytic activity for H2O2 electroreduction in alkaline medium
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Francisco Manoel dos Santos Garrido, Fagner da Silva Moura, Rachel Dias dos Santos, Bruna Teixeira da Fonseca, Paulo José Sousa Maia, Annelise Casellato, Marta Eloisa Medeiros, Sinara de Fatima Freire dos Santos, and Regina Helena de Almeida Santos
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Schiff base ,Coordination sphere ,Coordination polymer ,Ligand ,Imine ,Inorganic chemistry ,Metals and Alloys ,chemistry.chemical_element ,Bridging ligand ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Nickel ,chemistry ,NÍQUEL ,Octahedral molecular geometry ,Polymer chemistry ,Materials Chemistry ,0210 nano-technology - Abstract
A Ni(II) coordination polymer [C42H42K2N4Ni4O27] has been synthesized under open-air mild reaction conditions and characterized by physicochemical and spectroscopic methods. The X-ray crystal structure of the complex has been obtained. The crystallographic data revealed that each metal center is in a distorted octahedral geometry where the ligand coordinates to the metal centers by a nitrogen from the imine group, an oxygen from the carboxylic acid and a phenoxide group as an endogenous bridge to the metal centers. The coordination sphere is completed by an acetate, coordinated as an exogenous bridging ligand to both nickel centers, plus one terminal water ligand on each nickel. The polymeric structure is an infinite chain involving the binuclear nickel structure and K+ ions. Carbon paste electrodes modified with the Ni(II) coordination polymer were prepared, and the electrochemical behavior and electrocatalytic activity toward H2O2 reduction were investigated. The electrochemical results suggest that this Ni(II) coordination polymer has good catalytic activity with respect to H2O2 reduction.
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- 2017
12. THEORETICAL STUDY OF THE BINUCLEAR COMPLEXES OF MANGANESE (II) WITH LIGAND 2-HYDROXYBENZYLGLYCINE, POSSIBLES MIMICS FOR CATECHOL OXIDASE
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Sergio Machado, Annelise Casellato, and Everton Tomaz da Silva
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Chemistry ,Ligand ,Stereochemistry ,Density functional theory ,General Chemistry ,HOMO/LUMO ,Medicinal chemistry ,Catalysis - Abstract
This work applies the Density Functional Theory (DFT) to study binuclear complexes of Mn2+ with the ligand 2-hydroxibenzilglycine and its substituted derivatives. The results showed the isomer 2 with multiplicity 11-ete as the most stable between all the structures and multiplicities obtained. Then, the most stable complex with the -OCH3, -Br, -Cl and -NO2 substituents were analyzed. Finally, the absolute hardness and the percentage of LUMO orbital participation for the substituted complexes were evaluated. Among them, the complexes with -NO2, -H, -Br groups were more likely to play the catalytic activity, respectively.
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- 2016
13. Electronic Structure and Spectro-Structural Correlations of FeIIIZnII Biomimetics for Purple Acid Phosphatases: Relevance to DNA Cleavage and Cytotoxic Activity
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Andrew Dick, Elene C. Pereira-Maia, Hernán Terenzi, Rosely A. Peralta, Flávia C. S. de Paula, Mark J. Riley, Claus Tröger Pich, Graeme R. Hanson, Ricardo Alexandre Alves de Couto, Eduardo E. Castellano, Rafael Jovito, Annelise Casellato, Ademir Neves, Adailton J. Bortoluzzi, Patricia Cardoso Severino, Sergio Machado, Lawrence R. Gahan, Gerhard Schenk, Bernardo de Souza, Fernando R. Xavier, Tiago Bortolotto, and Faruk Nome
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Models, Molecular ,Circular dichroism ,Cell Survival ,Pyridines ,Stereochemistry ,Acid Phosphatase ,Crystal structure ,Crystallography, X-Ray ,Ferric Compounds ,Catalysis ,Inorganic Chemistry ,Biomimetic Materials ,Cell Line, Tumor ,Organometallic Compounds ,Humans ,Moiety ,DNA Cleavage ,Physical and Theoretical Chemistry ,Glycoproteins ,biology ,Ligand ,Chemistry ,Circular Dichroism ,Electron Spin Resonance Spectroscopy ,Active site ,Purple acid phosphatases ,ESPECTROSCOPIA ,Kinetics ,Zinc ,Crystallography ,Octahedron ,biology.protein - Abstract
Purple acid phosphatases (PAPs) are a group of metallohydrolases that contain a dinuclear Fe(III)M(II) center (M(II) = Fe, Mn, Zn) in the active site and are able to catalyze the hydrolysis of a variety of phosphoric acid esters. The dinuclear complex [(H(2)O)Fe(III)(μ-OH)Zn(II)(L-H)](ClO(4))(2) (2) with the ligand 2-[N-bis(2-pyridylmethyl)aminomethyl]-4-methyl-6-[N'-(2-pyridylmethyl)(2-hydroxybenzyl) aminomethyl]phenol (H(2)L-H) has recently been prepared and is found to closely mimic the coordination environment of the Fe(III)Zn(II) active site found in red kidney bean PAP (Neves et al. J. Am. Chem. Soc. 2007, 129, 7486). The biomimetic shows significant catalytic activity in hydrolytic reactions. By using a variety of structural, spectroscopic, and computational techniques the electronic structure of the Fe(III) center of this biomimetic complex was determined. In the solid state the electronic ground state reflects the rhombically distorted Fe(III)N(2)O(4) octahedron with a dominant tetragonal compression aligned along the μ-OH-Fe-O(phenolate) direction. To probe the role of the Fe-O(phenolate) bond, the phenolate moiety was modified to contain electron-donating or -withdrawing groups (-CH(3), -H, -Br, -NO(2)) in the 5-position. The effects of the substituents on the electronic properties of the biomimetic complexes were studied with a range of experimental and computational techniques. This study establishes benchmarks against accurate crystallographic structural information using spectroscopic techniques that are not restricted to single crystals. Kinetic studies on the hydrolysis reaction revealed that the phosphodiesterase activity increases in the order -NO(2) ←Br ←H ←CH(3) when 2,4-bis(dinitrophenyl)phosphate (2,4-bdnpp) was used as substrate, and a linear free energy relationship is found when log(k(cat)/k(0)) is plotted against the Hammett parameter σ. However, nuclease activity measurements in the cleavage of double stranded DNA showed that the complexes containing the electron-withdrawing -NO(2) and electron-donating -CH(3) groups are the most active while the cytotoxic activity of the biomimetics on leukemia and lung tumoral cells is highest for complexes with electron-donating groups.
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- 2010
14. Dinuclear copper(II) complexes of a novel 3-(aminomethyl)naphthoquinone Mannich base: Synthesis, structural, magnetic and electrochemical studies
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Antonio S. Mangrich, Miguel A. Novak, Amanda P. Neves, Kelly C.B. Maia, Annelise Casellato, Lorenzo do Canto Visentin, and Maria D. Vargas
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Chemistry ,Dimer ,Inorganic chemistry ,chemistry.chemical_element ,Mannich base ,Electrochemistry ,Magnetic susceptibility ,Copper ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,Intramolecular force ,X-ray crystallography ,Materials Chemistry ,Physical and Theoretical Chemistry ,Mannich reaction - Abstract
A novel versatile tridentate 3-(aminomethyl)naphthoquinone proligand, 3-[N-(2-pyridylmethyl)aminobenzyl]-2-hydroxy-1,4-naphthoquinone (HL), was obtained from the Mannich reaction of 2-hydroxy-1,4-naphthoquinone (Lawsone) with 2-aminomethylpyridine (amp) and benzaldehyde. The reactions of HL with CuCl2·2H2O yielded two novel dinuclear copper(II) complexes, [Cu(L)(H2O)(μ-Cl)Cu(L)Cl] (1b), [CuCl(L)(μ-Cl)Cu(amp)Cl] (2) and a polymeric compound, [Cu(L)Cl)]n (1a), whose relative yields were sensitive to temperature, reagents concentration and presence of base. The crystalline structures of 1b and 2 were determined by X-ray diffraction studies. The two copper atoms in complex 1b are connected by a single chloro bridge with a Cu⋯Cu separation of 4.1342(8) A and Cu(1)–Cl(1)–Cu(2) angle of 109.31(4)°. In complex 2 the two copper atoms are held together by a chloro and a naphthalen-2-olate bridges [Cu(1)–Cl(2)–Cu(2) and Cu(1)–O(1)–Cu(2) angles being 83.31(3) and 109.70(9)°, respectively, and the Cu⋯Cu separation, 3.3476(9) A]. As expected, variable-temperature magnetic susceptibility measurements of complex 1b showed weak antiferromagnetic intramolecular coupling between the copper(II) centers, with J = −5.7 cm−1, and evidenced for complex 2 strong antiferromagnetic coupling, with J ∼ −120 cm−1. Furthermore, the magnetic behaviour of compound 1a suggested an infinite 1D coordination polymeric structure in which the copper(II) centers are connected by Cl–Cu–Cl bridges. Solution data (UV–Vis spectroscopy and cyclic voltammetry) indicated structural changes of 2 and 1a in CH3CN, and evidenced conversion of polymer 1a into dimer 1b.
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- 2010
15. Novel 2-(R-phenyl)amino-3-(2-methylpropenyl)-[1,4]-naphthoquinones: synthesis, characterization, electrochemical behavior and antitumor activity
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Letícia V. Costa-Lotufo, Lorenzo do Canto Visentin, Amanda P. Neves, J. Walkimar de M. Carneiro, Annelise Casellato, Manoel Odorico de Moraes, José Delano Barreto Marinho Filho, Alviclér Magalhães, Cláudia Pessoa, Celso A. Câmara, and Maria D. Vargas
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Antitumor activity ,B3LYP ,electrochemistry ,Chemistry ,aminonaphthoquinone ,arylamine ,antitumor activity ,Nor-lapachol ,General Chemistry ,Electrochemistry ,Medicinal chemistry - Abstract
Novel 2-(R-phenyl)amino-3-(2-methyl-propenyl)-[1,4]-naphthoquinones (R = H, 4-OMe, 4-Ferrocenyl, 4-Me, 3-Me, 4-I, 3-I, 4-CN, 3-CN, 4-NO2 and 3-NO2) derived from nor-lapachol [2-hydroxy-3-(2-methylpropenyl)-1,4-naphthoquinone] were obtained in good yields. Their structures were proposed on the basis of a single crystal X-ray diffraction study (R = OMe, 2b), ¹H and 13C NMR studies and calculations using the B3LYP functional and the 6-311+G(2d,p) basis set. The half-wave potentials of the aminonaphthoquinones and ¹H NMR chemical shifts of the 3-propenyl hydrogen in 2a-k show good correlation with the substituent Hammett constants on the phenylamino ring. The antitumor assays showed promising activity for substrate methoxy-nor-lapachol 1 and the 4-ferrocenyl derivative 2c. Novas 2-(R-fenil)amino-3-(2-metilpropenil)-[1,4]-naftoquinonas (R = H, 4-OMe, 4-Ferrocenil, 4-Me, 3-Me, 4-I, 3-I, 4-CN, 3-CN, 4-NO2 e 3-NO2) derivadas do nor-lapachol [2-hidroxi-3-(2-metilpropenil)-1,4-naftoquinona] foram obtidas em bons rendimentos. A estrutura dos compostos foi proposta com base em estudos de difração de raios-X (R = OMe, 2b), dados de RMN de ¹H e 13C e cálculos teóricos utilizando o funcional B3LYP e a base 6-311+G(2d,p). Os potenciais de meia-onda das aminonaftoquinonas e o deslocamento químico do hidrogênio da cadeia 3-propenil dos compostos 2a-k mostraram boa correlação com as constantes de Hammett dos substituintes presentes no anel fenileno. A avaliação da citotoxicidade evidenciou atividade antitumoral promissora para o substrato metóxi-nor-lapachol 1 e o derivado 4-ferrocenil 2c.
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- 2010
16. Theoretical studies of the tautomerism in 3-(2-R-Phenylhydrazono)-naphthalene- 1,2,4-triones: synthesis of copper(II) complexes and studies of antibacterial and antitumor activities
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Letícia V. Costa-Lotufo, Manoel Odorico de Moraes, J. Walkimar de M. Carneiro, José Delano Barreto Marinho Filho, Fernando de C. da Silva, Jussara P. Barbosa, Annelise Casellato, Acácio I. Francisco, Thaís P. Fragoso, Maria D. Vargas, Antonio S. Mangrich, Vitor F. Ferreira, and Cláudia Pessoa
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biology ,Stereochemistry ,Bacillus cereus ,Substituent ,General Chemistry ,Bacillus subtilis ,biology.organism_classification ,Tautomer ,Enterococcus faecalis ,tautomerism ,chemistry.chemical_compound ,naphthoquinones ,antibacterial activity ,chemistry ,Phenylene ,copper(II) complexes ,antitumor activity ,Antibacterial activity ,hydrazone compounds ,Conformational isomerism - Abstract
DFT calculations using the B3LYP and PBE1PBE functionals with the standard 6-31G(d) and 6-311+G(2d,p) basis sets were carried out for the 3-(2-phenylhydrazone)-naphthalene-1,2,4-trione system in solution (dmso) and in the gas phase, and showed the keto-hydrazone forms (rotamers Ia and Ib) to be more stable than the enol-azo forms (rotamers IIa and IIb, by about 14 kcal mol-1) and III (by approximately 6 kcal mol-1), independently of the nature of the substituent in the phenylene ring. These results were confirmed by spectroscopic data on the derivatives HL1-HL13, obtained from 2-hydroxy-1,4-naphthoquinone and arylamines (R = 4-OMe, 4-N2-C6H5, 4-Cl, 4-I, 3-I, 2-I, 4-COOH, 3-COOH, 4-CN, 3-CN, 4-NO2, 3-NO2, 2-NO2). The in vitro antitumor (against SF-295, HCT-8, MDAMB-435 and HL-60 cancer cell lines) and antibacterial activities (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa) of compounds HL1-HL13 and of their respective copper(II) complexes, [Cu(L1-13)2], were tested. In general, these compounds exhibited low antibacterial activity, except for HL5 (R = 3-I), more active than the control; however, the corresponding complex was inactive. In contrast, increased cytotoxicity was observed upon complexation. Complex [Cu(L13)2] (R = 3-NO2) presented moderate cytotoxicity against human leukemia (HL-60). Cálculos teóricos utilizando os funcionais B3LYP e PBE1PBE e as bases 6-31G(d) e 6-311+G(2d,p) para o sistema 3-(2-fenil-hidrazona)-naftaleno-1,2,4-triona, em solução (dmso) e em fase gasosa, evidenciaram, em ambos os casos, a maior estabilidade da forma ceto-hidrazona (rotâmeros Ia e Ib) comparada às formas enol-azo (rotâmeros IIa/IIb, por volta de 14 kcal mol-1) e III (aproximadamente 6 kcal mol-1). A natureza do substituinte no grupo fenil não influenciou a estabilidade relativa dos tautômeros. Estes resultados foram confirmados por dados espectroscópicos dos derivados HL1-HL13, sintetizados a partir da 2-hidroxi-1,4-naftoquinona e arilaminas (R = 4-OMe, 4-N2-C6H5, 4-Cl, 4-I, 3-I, 2-I, 4-COOH, 3-COOH, 4-CN, 3-CN, 4-NO2, 3-NO2, 2-NO2). A avaliação da atividade anticâncer in vitro (contra linhagens de células cancerosas SF-295, HCT-8, MDAMB-435 e HL-60) e bactericida (Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia e Pseudomonas aeruginosa) dos compostos HL1-HL13 e dos seus respectivos complexos de cobre(II), [Cu(L1-13)2], foi avaliada. Em geral a atividade bactericida foi baixa, exceto para o derivado HL5 (R = 3-I), mais ativo do que o controle; entretanto, seu complexo não foi ativo. Por outro lado, a complexação levou, em geral, ao aumento da atividade antitumoral dos pré-ligantes. O complexo [Cu(L13)2] (R = 3-NO2) apresentou moderada citotoxicidade contra leucemia humana (HL-60).
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- 2010
17. New Synthetic Routes for the Preparation of 2-Amino-3-hydroxy-1,4-naphthoquinone
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Maria D. Vargas, Acácio I. Francisco, and Annelise Casellato
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chemistry.chemical_compound ,Nitrogen atom ,Chemistry ,Organic Chemistry ,Organic chemistry ,1,4-Naphthoquinone ,Quinone Compound - Abstract
On the basis of biological and structural properties, 1,2- and 1,4-naphthoquinones are considered privileged structures in medicinal chemistry. 1 The presence of a nitrogen atom in quinone compound...
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- 2009
18. Synthesis, Structure, and Physicochemical Properties of Dinuclear NiII Complexes as Highly Efficient Functional Models of Phosphohydrolases
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Rafael Jovito, Bruno Szpoganicz, Annelise Casellato, Ademir Neves, Michal Rams, Zbigniew Tomkowicz, Rosely A. Peralta, Alessandra Greatti, Fernanado R. Xavier, Marciela Scarpellini, Adailton J. Bortoluzzi, Wolfgang Haase, and Marcos A. de Brito
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Models, Molecular ,Magnetic Resonance Spectroscopy ,Molecular Structure ,biology ,Stereochemistry ,Chemistry ,Ligand ,Metal ions in aqueous solution ,Potentiometric titration ,Active site ,Molar conductivity ,Crystallography, X-Ray ,Phosphoric Monoester Hydrolases ,Catalysis ,Inorganic Chemistry ,Metal ,Nickel ,Magnetochemistry ,visual_art ,Polymer chemistry ,biology.protein ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry - Abstract
As metal ions are present in the catalytic sites of several enzymes, attention has been focused on the synthesis and characterization of metal complexes able to act as biomimetic functional and structural models for these systems. In this study, a novel dinuclear NiII complex was synthesized, [Ni2(L2)(OAc)2(CH3CN)]BPh4 (2) (HL2=2-[N-(2-(pyridyl-2-yl)ethyl)(1-methylimidazol-2-yl)amin omethyl]-4-methyl-6-[N-(2-(imidazol-4-yl)ethyl)amino methyl]phenol), employing a new unsymmetrical dinucleating ligand containing N,O-donor groups as a model for hydrolases. Complex 2 was characterized by a variety of techniques including: elemental analysis, infrared and UV-vis spectroscopies, molar conductivity, electrochemistry, potentiometric titration, magnetochemistry, and single-crystal X-ray diffractometry. The structural and magnetochemical data of 2 allow us to consider this complex as a structural model for the active site of the ureases, as previously reported for [Ni2(L1)(OAc)2(H2O)]ClO4.H2O (1) (HL1=2-[N-bis-(2-pyridylmethyl)aminomethyl]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl] phenol). The characterization of complexes 1 and 2 (mainly by X-ray diffraction and potentiometric titration) led us to study their reactivities toward the hydrolysis of the substrate bis(2,4-dinitrophenyl)phosphate (2,4-BDNPP). These studies revealed that complexes 1 and 2 show the best catalytic activity reported so far, with acceleration rates 8.8x10(4) and 9.95x10(5) times faster, respectively, than the uncatalyzed hydrolysis of 2,4-BDNPP. Catalytic activity of 2 on 2,4-DNPP showed that the monoester is hydrolyzed 27 times slower than the 2,4-BDNPP diester under identical experimental conditions. Therefore, 1 and 2 can undoubtedly be considered highly efficient functional models of the phosphohydrolases.
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- 2008
19. The reaction mechanism of the Ga(III)Zn(II) derivative of uteroferrin and corresponding biomimetics
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Sarah J. Smith, Bruno Szpoganicz, Mark J. Riley, Adailton J. Bortoluzzi, Annelise Casellato, Lawrence R. Gahan, Kieran S. Hadler, Ademir Neves, Nataša Mitić, and Gerhard Schenk
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Coordination sphere ,Pyridines ,Swine ,Acid Phosphatase ,Inorganic chemistry ,Crystallography, X-Ray ,Ligands ,Biochemistry ,Catalysis ,Galium ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,Phenols ,Nucleophile ,Biomimetic Materials ,Animals ,Reactivity (chemistry) ,Nuclear Magnetic Resonance, Biomolecular ,Binding Sites ,biology ,Tartrate-Resistant Acid Phosphatase ,Ligand ,Active site ,Purple acid phosphatases ,Isoenzymes ,Zinc ,Crystallography ,chemistry ,visual_art ,biology.protein ,visual_art.visual_art_medium ,Hydroxide - Abstract
Purple acid phosphatase from pig uterine fluid (uteroferrin), a representative of the diverse family of binuclear metallohydrolases, requires a heterovalent Fe(III)Fe(II) center for catalytic activity. The active-site structure and reaction mechanism of this enzyme were probed with a combination of methods including metal ion replacement and biomimetic studies. Specifically, the asymmetric ligand 2-bis{[(2-pyridylmethyl)-aminomethyl]-6-[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl}-4-methylphenol and two symmetric analogues that contain the softer and harder sites of the asymmetric unit were employed to assess the site selectivity of the trivalent and divalent metal ions using (71)Ga NMR, mass spectrometry and X-ray crystallography. An exclusive preference of the harder site of the asymmetric ligand for the trivalent metal ion was observed. Comparison of the reactivities of the biomimetics with Ga(III)Zn(II) and Fe(III)Zn(II) centers indicates a higher turnover for the former, suggesting that the M(III)-bound hydroxide acts as the reaction-initiating nucleophile. Catalytically active Ga(III)Zn(II) and Fe(III)Zn(II) derivatives were also generated in the active site of uteroferrin. As in the case of the biomimetics, the Ga(III) derivative has increased reactivity, and a comparison of the pH dependence of the catalytic parameters of native uteroferrin and its metal ion derivatives supports a flexible mechanistic strategy whereby both the mu-(hydr)oxide and the terminal M(III)-bound hydroxide can act as nucleophiles, depending on the metal ion composition, the geometry of the second coordination sphere and the substrate.
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- 2007
20. EPR and semi-empirical studies as tools to assign the geometric structures of FeIII isomer models for transferrins
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Adailton J. Bortoluzzi, Ivo Vencato, Antonio S. Mangrich, Marciela Scarpellini, Sergio Machado, Annelise Casellato, and Ademir Neves
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Analytical chemistry ,Molar conductivity ,Ethylenediamine ,General Chemistry ,Electrochemistry ,Redox ,law.invention ,chemistry.chemical_compound ,Crystallography ,chemistry ,law ,Cyclic voltammetry ,Electron paramagnetic resonance ,Cis–trans isomerism ,Monoclinic crystal system - Abstract
The reaction of Fe(ClO4)3.nH2O with N,N'-bis[(2-hydroxybenzyl)-N,N' -bis(1-methylimidazole-2-yl-methyl)]ethylenediamine (H2bbimen) affords two geometric isomers, A and B, of the complex cation [Fe(bbimen)]+, which were fully characterized by IR and UV-visible spectroscopies, ESI mass spectrometry, molar conductivity measurements, cyclic voltammetry, spectroelectrochemistry and EPR spectroscopy. The geometry of one of these isomers has been clearly demonstrated through X-ray crystallographic analysis. It crystallizes in the monoclinic system, space group P21/c, a = 14.104 (3), b = 15.626 (3), c = 13.291 (3) A, b = 98.07 (3)o, Z = 4, R1 = 6.35% and wR2 = 20.57%. The electrochemical properties of [Fe(bbimen)]+ (-0.58 V versus NHE) are quite similar to those of transferrins (-0.52 V versus NHE) and indicate that it is a good model for the redox potential of these metalloenzymes. EPR spectroscopy was the only spectroscopic technique able to differentiate the isolated isomers A and B. EPR studies revealed that isomer A is better described as a rhombically distorted (E/D @ 0.33) high-spin FeIII complex (g1 @ 4.1 with a shoulder at g2 @ 9.0), while the spectrum of B has a set of lines at g1 @ 3.0, g2 @ 3.6 and g3 @ 5.1, in addition to the line at g1 @ 4.2 and a shoulder at g2 @ 9.0, which have been ascribed to FeIII complexes in axial symmetry (E/D @ 0.22). Semi-empirical theoretical studies, combined with EPR data, were essential to the proposition of the geometric structures of A and B.
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- 2006
21. Synthesis and Characterization of Modified Chitosan Through Immobilization of Complexing Agents
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Annelise Casellato, Mauro C. M. Laranjeira, Valfredo T. Fávere, Karin Cristiane Justi, and Ademir Neves
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Polymers and Plastics ,Tertiary amine ,Metal ions in aqueous solution ,Organic Chemistry ,Chemical modification ,engineering.material ,Condensed Matter Physics ,Chitosan ,chemistry.chemical_compound ,chemistry ,Sequestrant ,Materials Chemistry ,engineering ,Organic chemistry ,Chelation ,Biopolymer ,Selectivity ,Nuclear chemistry - Abstract
The complexation agents 2[-bis-(pyridylmethyl)aminomethyl]-4-methyl-6-formyl-phenol (BPMAMFF) and 2-[2-(hydroxybenzyl)-2-(pyridylmethyl)aminomethyl]-4-methyl-6-formyl-phenol (HBPAMFF) were immobilized on chitosan biopolymer in order to obtain new adsorbent materials for metal ions. The chitosan derivatives were characterized by IR spectroscopy, DSC, TGA, and CHN analysis. The characterization study proved that the chitosan surface was chemically modified with both complexing agents and however, it is expected that these modifications improve the selectivity for metal ions specific in relation to the chitosan.
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- 2005
22. Spectroscopic studies of composite obtained from solid state reaction between a mononuclear vanadium(IV) complex and kaolinite
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Tatiana Lopez Fernandez, Marciela Scarpellini, Antonio S. Mangrich, Annelise Casellato, Ana P. Mangoni, and Edivaltris I. P. De Rezende
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Stereochemistry ,Chemistry ,Solid-state ,General Chemistry ,Solid material ,law.invention ,lcsh:Chemistry ,Paramagnetism ,lcsh:QD1-999 ,law ,DRUV-VIS ,Physical chemistry ,Amine gas treating ,composite ,Electron paramagnetic resonance ,Spectroscopy ,Second derivative ,EPR spectroscopy - Abstract
p. 257-261 Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2014-08-12T15:41:53Z No. of bitstreams: 1 Edivaltris I. P. De Rezende.pdf: 341853 bytes, checksum: 451bfcd6b86617e1880b27e0dbad8c26 (MD5) Made available in DSpace on 2014-08-12T15:41:53Z (GMT). No. of bitstreams: 1 Edivaltris I. P. De Rezende.pdf: 341853 bytes, checksum: 451bfcd6b86617e1880b27e0dbad8c26 (MD5) Previous issue date: 2012 The use of probes, such as paramagnetic species diluted in diamagnetic materials in EPR spectroscopy, and mathematical tools such, as the Kubelka-Munk function in DRUV-VIS spectroscopy are strategies in the analysis of complex mixtures of solid materials. The results obtained here show that the solid state reaction between the complex, [VO(acac)(BMIMAPY)] [ClO4], BMIMAPY = [(bis(1-methylimidazole-2-yl)methyl)(2-(pyridyl-2-yl)ethyl) amine] and acac = acetilacetonate, with kaolinite turns possible to obtain anisotropic EPR spectrum of the complex with a reasonable level of resolution. The study by DRUV-VIS using the method of second derivative mode of the Kubelka-Munk function revealed new complex structural arrangements, a solid hitherto unknown.
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- 2012
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23. Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen
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Tatiana Lopez Fernandez, Roberto B. Faria, Annelise Casellato, Marciela Scarpellini, Carlos B. Pinheiro, Antonio S. Mangrich, Sergio Machado, Elizabeth T. Souza, Luciana R. Martins, Bernardo de Souza, and Silvio Rachinski
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Steric effects ,Reaction mechanism ,Ligand ,Cyclohexanol ,Cyclohexanone ,molecular structure ,General Chemistry ,Photochemistry ,Medicinal chemistry ,Active center ,chemistry.chemical_compound ,catechol oxidase ,chemistry ,Pyridine ,binuclear copper complexes ,hydrocarbon oxidation ,HOMO/LUMO - Abstract
The tridentate ligands HL1, [(2-hydroxybenzyl)(2-(imidazol-2-yl)ethyl)]amine, and HL2, [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]amine, were used to synthesize binuclear CuII complexes, [Cu2(L1)2]Cl2•2H2O, complex 1, and [Cu2(L2)2](ClO4)2•1.5H2O, complex 2, in order to obtain catalysts for oxidative processes. Both complexes were characterized by elemental analysis, IR, UV-Vis and EPR spectroscopies. In addition, they were studied by cyclic voltammetry and potentiometric titration in order to investigate their behavior in solution. The crystal structure of complex 1 revealed a binuclear cation where the metal centers are bridged by two phenoxo groups. This arrangement provides a Cu...Cu distance of 3.043(10) Å, which is similar to the observed for catechol oxidase (2.90 Å). The catalytic reactivities of both complexes were investigated for hydrocarbon and catechol oxidations. Complexes 1 and 2 led to low overall hydrocarbon oxidation conversion values of 6.34 % and 7.15 %, respectively. However, for complex 1, only cyclohexanol (Cy-OH) and cyclohexanone (Cy=O) were isolated as reaction products, with selectivities of 68.1% for Cy-OH. This low overall conversion is tentatively attributed to steric hindrance effects produced by the non-coplanar aromatic rings of the ligand scaffolds, which suggest that the access of the hydrocarbon molecule to the binuclear active center is a determinant step in the reaction mechanism. Investigation of catecholase activities has shown high efficiencies, with complex 2 being more active than complex 1. It indicates that the pyridine-containing ligand is able to stabilize the intermediate CuI CuI center which is proposed to be formed in this process. This is corroborated by the strong participation of pyridine in the LUMO (lowest unoccupied molecular orbital) of complex 2, which can help to accommodate the additional negative charge when the complex is reduced from CuII CuII to CuI CuI. Dois ligantes tridentados, HL1, [(2-hidroxibenzil)(2-(imidazol-2-il)etil)]amina, e HL2, [(2-hidroxibenzil)(2-(piridil-2-il)etil]amina, foram usados na síntese dos complexos binucleares [Cu2(L1)2]Cl2•2H2O, complexo 1, e [Cu2(L2)2](ClO4)2•1.5H2O, complexo 2,para serem empregados como catalisadores em processos de oxidação. Os complexos foram caracterizados por análise elementar e espectroscopias na região do infravermelho, ultravioleta-visível e ressonância paramagnética eletrônica. Foram também estudados por voltametria cíclica e titulação potenciométrica, a fim de caracterizar seus comportamentos em solução. A resolução da estrutura cristalina do complexo 1 mostrou um cátion binuclear contendo dois grupos fenóxido em ponte. Este arranjo possui uma distância Cu...Cu de 3.043(10) Å, similar à observada na catecol oxidase (2.90 Å). Os comportamentos catalíticos destes complexos foram investigados nas oxidações de cicloexano e de catecol. Na oxidação de cicloexano observou-se baixa atividade para ambos os complexos, que pode ser atribuída ao estereoimpedimento produzido pela falta de coplanaridade entre os anéis aromáticos do arcabouço dos ligantes, sugerindo que a aproximação entre o substrato e o centro ativo binuclear é uma etapa determinante no mecanismo da reação. Com relação à atividade de catecolase, foram observadas altas eficiências, com o complexo 2 sendo mais ativo que o complexo 1. Isto indica que o ligante piridina é capaz de estabilizar melhor o intermediário proposto para esse processo, que contém o centro CuI CuI. Isto é corroborado pela grande participação da piridina no LUMO (lowest unoccupied molecular orbital) do complexo 2, que pode ajudar a acomodar a carga negativa adicional quando o complexo é reduzido da forma CuII CuII para CuI CuI.
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- 2010
24. ChemInform Abstract: New Synthetic Routes for the Preparation of 2-Amino-3-hydroxy-1,4-naphthoquinone
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Acácio I. Francisco, Annelise Casellato, and Maria D. Vargas
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chemistry.chemical_compound ,chemistry ,Nitrogen atom ,Organic chemistry ,General Medicine ,1,4-Naphthoquinone ,Quinone Compound - Abstract
On the basis of biological and structural properties, 1,2- and 1,4-naphthoquinones are considered privileged structures in medicinal chemistry. 1 The presence of a nitrogen atom in quinone compound...
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- 2009
25. Unsymmetrical Fe(III)Co(II) and Ga(III)Co(II) complexes as chemical hydrolases: biomimetic models for purple acid phosphatases (PAPs)
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Gerhard Schenk, Adailton J. Bortoluzzi, Zbigniew Tomkowicz, Hernán Terenzi, Lawrence R. Gahan, Andrew Ozarowski, J. Krzystek, Sergei Ostrovsky, Annelise Casellato, Bruno Szpoganicz, Patricia Cardoso Severino, Joshua Telser, Ademir Neves, Fernando R. Xavier, Wolfgang Haase, and Rosely A. Peralta
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Stereochemistry ,Acid Phosphatase ,Gallium ,Ferric Compounds ,Catalysis ,Absorption ,Inorganic Chemistry ,chemistry.chemical_compound ,Magnetics ,Nucleophile ,Biomimetics ,Electrochemistry ,Animals ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Isostructural ,Glycoproteins ,Ligand ,Circular Dichroism ,Hydrolysis ,Electron Spin Resonance Spectroscopy ,Titrimetry ,Bioinorganic chemistry ,Cobalt ,DNA ,Purple acid phosphatases ,Crystallography ,Kinetics ,chemistry ,Biocatalysis ,Potentiometry ,Hydroxide ,Cattle - Abstract
The design and development of suitable biomimetic catalytic systems capable of mimicking the functional properties of enzymes continues to be a challenge for bioinorganic chemists. In this study, we report on the synthesis, X-ray structures, and physicochemical characterization of the novel isostructural [Fe(III)Co(II)(BPBPMP)(mu-OAc)(2)]ClO(4) (1) and [Ga(III)Co(II)(BPBPMP)(mu-OAc)(2)]ClO(4) (2) complexes with the unsymmetrical dinucleating ligand H(2)BPBPMP (2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol). The previously reported complex [Fe(III)Zn(II)(BPBPMP)(mu-OAc)(2)]ClO(4) (3) was investigated here by electron paramagnetic resonance for comparison with such studies on 1 and 2. A magneto-structural correlation between the exchange parameter J (cm(-1)) and the average bond lengh d (A) of the [Fe(III)-O-M(II)] structural unit for 1 and for related isostructural Fe(III)M(II) complexes using the correlation J = -10(7) exp(-6.8d) reveals that this parameter is the major factor that determines the degree of antiferromagnetic coupling in the series [(BPBPMP)Fe(III)(mu-OAc)(2)M(II)](+) (M(II) = Mn, Fe, Co, Ni) of complexes. Potentiometric and spectrophotometric titrations along with electronic absorption studies show that, in aqueous solution, complexes 1 and 2 generate the [(HO)M(III)(mu-OH)Co(II)(H(2)O)] complex as the catalytically active species in diester hydrolysis reactions. Kinetic studies on the hydrolysis of the model substrate bis(2,4-dinitrophenyl)phosphate by 1 and 2 show Michaelis-Menten behavior, with 2 being 35% more active than 1. In combination with k(H)/k(D) isotope effects, the kinetic studies suggest a mechanism in which a terminal M(III)-bound hydroxide is the hydrolysis-initiating nucleophilic catalyst. In addition, the complexes show maximum catalytic activity in DNA hydrolysis near physiological pH. The modest reactivity difference between 1 and 2 is consistent with the slightly increased nucleophilic character of the Ga(III)-OH terminal group in comparison to Fe(III)-OH in the dinuclear M(III)Co(II) species.
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- 2009
26. Catalase vs peroxidase activity of a manganese(II) compound: identification of a Mn(III)-(mu-O)(2)-Mn(IV) reaction intermediate by electrospray ionization mass spectrometry and electron paramagnetic resonance spectroscopy
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Érika S. Bull, Giselle C. Silva, Graeme R. Hanson, Christiane Fernandes, Christopher J. Noble, Michelle R. Rocha, Marcos N. Eberlin, O. A. C. Antunes, Josane A. Lessa, Mario Benassi, Rodrigo Ramos Catharino, Annelise Casellato, Gerhard Schenk, and Adolfo Horn
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inorganic chemicals ,Manganese ,Spectrometry, Mass, Electrospray Ionization ,Aqueous solution ,Absorption spectroscopy ,Electrospray ionization ,Inorganic chemistry ,Electron Spin Resonance Spectroscopy ,chemistry.chemical_element ,Disproportionation ,Reaction intermediate ,Catalase ,Catalysis ,law.invention ,Inorganic Chemistry ,Oxygen ,chemistry ,law ,Biomimetic Materials ,Organometallic Compounds ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance ,Peroxidase - Abstract
Herein, we report reactivity studies of the mononuclear water-soluble complex [Mn(II)(HPClNOL)(eta(1)-NO(3))(eta(2)-NO(3))] 1, where HPClNOL = 1-(bis-pyridin-2-ylmethyl-amino)-3-chloropropan-2-ol, toward peroxides (H(2)O(2) and tert-butylhydroperoxide). Both the catalase (in aqueous solution) and peroxidase (in CH(3)CN) activities of 1 were evaluated using a range of techniques including electronic absorption spectroscopy, volumetry (kinetic studies), pH monitoring during H(2)O(2) disproportionation, electron paramagnetic resonance (EPR), electrospray ionization mass spectrometry in the positive ion mode [ESI(+)-MS], and gas chromatography (GC). Electrochemical studies showed that 1 can be oxidized to Mn(III) and Mn(IV). The catalase-like activity of 1 was evaluated with and without pH control. The results show that the pH decreases when the reaction is performed in unbuffered media. Furthermore, the activity of 1 is greater in buffered than in unbuffered media, demonstrating that pH influences the activity of 1 toward H(2)O(2). For the reaction of 1 with H(2)O(2), EPR and ESI(+)-MS have led to the identification of the intermediate [Mn(III)Mn(IV)(mu-O)(2)(PClNOL)(2)](+). The peroxidase activity of 1 was also evaluated by monitoring cyclohexane oxidation, using H(2)O(2) or tert-butylhydroperoxide as the terminal oxidants. Low yields (7%) were obtained for H(2)O(2), probably because it competes with 1 for the catalase-like activity. In contrast, using tert-butylhydroperoxide, up to 29% of cyclohexane conversion was obtained. A mechanistic model for the catalase activity of 1 that incorporates the observed lag phase in O(2) production, the pH variation, and the formation of a Mn(III)-(mu-O)(2)-Mn(IV) intermediate is proposed.
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- 2009
27. An unprecedented Fe(III)(mu-OH)Zn(II) complex that mimics the structural and functional properties of purple acid phosphatases
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Annelise Casellato, Rosely A. Peralta, Adailton J. Bortoluzzi, Gerhard Schenk, Eduardo Ernesto Castellano, Ademir Neves, Mauricio Lanznaster, Mark J. Riley, and Paul Herrald
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Models, Molecular ,Molecular Structure ,Stereochemistry ,Chemistry ,Acid Phosphatase ,General Chemistry ,Crystal structure ,Purple acid phosphatases ,Phosphate ,Biochemistry ,Ferric Compounds ,Catalysis ,Hydrolysis ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Nucleophile ,Zinc Compounds ,Hydroxide ,Structural unit ,Glycoproteins - Abstract
This communication reports the synthesis and X-ray structure of the first mixed-valence FeIIIZnII complex containing the FeIII(μ-OH)ZnII structural unit. Based on the structure, physicochemical solution studies, and the catalytic properties toward the hydrolysis of the diester 2,4-bis(dinitrophenyl)phosphate (BDNPP), it is proposed that complex 1 employs a hydrolytic mechanism similar to that proposed for red kidney bean purple acid phosphatase, including a nucleophilic attack by the terminal, FeIII-bound hydroxide and the concomitant release of 2,4-dinitrophenolate. Furthermore, it is demonstrated that the μ-hydroxo group in the {FeIII(μ-OH)(μ-ROPO3)ZnII} intermediate is unable to hydrolyze the monoester 2,4-dinitrophenylphosphate (DNPP), which suggests that the μ-hydroxo group is a significantly poorer nucleophile than the terminally FeIII-bound OH- group.
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- 2007
28. First-transition-metal complexes containing the ligands 6-amino-6-methylperhydro-1,4-diazepine (AAZ) and a new functionalized derivative: can AAZ act as a mimetic ligand for 1,4,7-triazacyclononane?
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Bruno Szpoganicz, Annelise Casellato, Alessandra Greatti, Fernando R. Xavier, Ademir Neves, Ademir dos Anjos, Rosely A. Peralta, and Adailton J. Bortoluzzi
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Models, Molecular ,Molecular Structure ,Ligand ,Stereochemistry ,Molecular Mimicry ,Azepines ,Crystallography, X-Ray ,Ligands ,Inorganic Chemistry ,chemistry.chemical_compound ,Diazepine ,chemistry ,Transition metal ,Heterocyclic Compounds ,Nickel ,Organometallic Compounds ,Chelation ,Physical and Theoretical Chemistry ,Derivative (chemistry) - Abstract
The structure and physicochemistry of the [Ni(II)(AAZ)(2)](ClO(4))(2) (1) complex (AAZ = 6-amino-6-methylperhydro-1,4-diazepine), as a system that is able to mimic some important chelate properties of 1,4,7-triazacyclononane, are reported. The syntheses of a new unsymmetric AAZ-functionalized ligand and the structure of its first heterodinuclear Fe(III)Zn(II) complex are also presented.
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- 2005
29. Synthesis and Characterization of Modified Chitosan Through Immobilization of Complexing Agents.
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Karin Cristiane Justi, Valfredo T. Fávere, Mauro C. M. Laranjeira, Ademir Neves, and Annelise Casellato
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- 2005
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30. SÍNTESE E CARACTERIZAÇÃO DE COMPLEXOS DE COBRE (II) E ZINCO (II) COM DIPEPTÍDEOS DE INTERESSE BIOLÓGICO
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ALINE CRUZ DE MORAES REIS, JUDITH FELCMAN, BARBARA LUCIA DE ALMEIDA, NICOLAS ADRIAN REY, and ANNELISE CASELLATO
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO Este trabalho descreve a síntese e caracterização de quatro complexos de cobre (II) e quatro complexos de zinco (II), com dipeptídeos, no estado sólido. Os dipeptídeos envolvidos foram: glicil-glicina, glicil-valina, metionil-metionina, metionil-glicina e cisteinil-glicina, cujos aminoácidos fazem parte de algumas proteínas envolvidas em processos de neurodegeneração, mais especificamente na doença de Alzheimer. Embora os mecanismos que desencadeiam esta patologia não estejam ainda totalmente esclarecidos, sabe-se que os íons metálicos, como o cobre (II) e o zinco (II), interagem com o peptídeo beta-amilóide. Acredita-se que tais interações favoreçam a formação de agregados protéicos sólidos deste peptídeo, observados nos cérebros de pacientes com essa doença. Dessa forma, a obtenção e o estudo de modelos simples no estado sólido, sintetizados em condições próximas ao meio biológico, podem permitir uma melhor compreensão de possíveis interações de tais metais neste sítio protéico. Os compostos obtidos foram caracterizados utilizando as seguintes técnicas: análise elementar, absorção atômica, espectroscopia de infravermelho, espectroscopia Raman, espectroscopia de ultravioleta-visível, termogravimetria, RPE (para os complexos de cobre) e condutivimetria. Para os complexos de zinco, foram realizados cálculos teóricos mecânico-quânticos para obtenção de parâmetros geométricos e espectros de infravermelho. A análise dos compostos obtidos mostrou que os complexos de cobre e zinco com os dipeptídeos estão coordenados por átomos de oxigênio e nitrogênio. Nos complexos de peptídeos contendo enxofre, a coordenação também ocorre pelo átomo de enxofre (cobre com metionil-metionina e metionil-glicina e zinco com cisteinil-glicina). Os compostos obtidos para ambos os metais na proporção metal-ligante (1:1) mostram comportamento diferente dos estudos em solução e aqueles obtidos na proporção metal-ligante (1:2) mostram comportamento similar a complexos de metais com aminoácidos. This work describes the synthesis and characterization of copper (II) and zinc (II) complexes, with dipeptides in solid state. The dipeptides involved were: glycyl-glycine, glycyl-valine, methionyl-methionine, methionyl-glycine and cysteinyl-glycine, whose aminoacids take part in some proteins involved in neurodegeneration processes, more specifically in Alzheimer’s disease. Although the mechanisms that trigger this pathology are still not totally clear, it is known that metallic ions, such as copper (II) and zinc (II) interact with the beta-amyloid peptide. It seems that such interactions favor the formation of solid proteic aggregates of this peptide, observed in the brains of patients with Alzheimer’s disease. Thus, the obtaining and study of simple models in the solid state, synthesized in similar conditions to the biological medium, may allow a better understanding of the possible interactions of such metals in this proteic site. The compounds obtained were characterized using the following techniques: elemental analysis, atomic absorption, infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, thermogravimetry, EPR (for the copper complexes) and conductivimetry. For the zinc complexes, quantum-mechanical theoretical calculations were performed to obtain geometrical parameters and infrared spectra. The analysis of the compounds showed that the copper and zinc complexes with dipeptides are coordinated through oxygen and nitrogen atoms. In complexes of dipeptides containing sulfur, coordination trough the sulfur atom occurs too (copper with methionyl-methionine and methionyl-glycine and zinc with cysteinyl-glycine). The compounds obtained for both metals at the metal-ligand ratio (1:1) behave differently from those studied in solution e those obtained in the metal-ligand ratio (1:2) show similar behavior of metal complexes with aminoacids.
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- 2010
31. STUDY OF BINARY COMPLEXES OF ALUMINUM(III) WITH SULFUR AMINO ACIDS AND PHOSPHATE LIGANDS
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THAIS VALERIA BARREIROS ALVES, JUDITH FELCMAN, NICOLAS ADRIAN REY, ANNELISE CASELLATO, and ANDREA DE MORAES SILVA
- Abstract
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO O estudo de complexos binários de Al(III) com aminoácidos sulfurados (metionina, cisteína, homocisteína e penicilamina) e ligantes fosfatados (adenosina 5’-trifosfato e fosfocreatina) foi feito em solução aquosa por meio de titulações potenciométricas, de RMN de (13)C e (27)Al, de espectroscopia Raman, de modelagem molecular e de cálculos teóricos do espectro vibracional através do procedimento de cálculo DFT: B3LYP/6-311G. As titulações potenciométricas e o RMN de (13)C e (27)Al foram obtidos apenas para os complexos contendo aminoácidos. Através da potenciometria determinaram-se as constantes de estabilidade dos complexos binários de Al(III) com os aminoácidos e suas curvas de distribuição de espécies. Ao se analisar os valores de constantes obtidos percebe-se que o complexo Al-Penicilamina apresenta um valor maior que os demais complexos formados, indicando um comportamento distinto. Propôs-se que a penicilamina atuaria como tridentada através dos átomos de oxigênio do carboxilato, de nitrogênio da amina e de enxofre da sulfidrila, enquanto os outros atuariam como bidentados coordenando-se através dos átomos de oxigênio do carboxilato e de nitrogênio da amina. As distribuições de espécies em função do pH mostraram que no pH fisiológico há a predominância das espécies hidrolisadas do metal e do complexo. Os espetros de RMN de (13)C e de Raman e os cálculos teóricos confirmaram a possibilidade dos sítios coordenativos propostos para os aminoácidos. O RMN de (27)Al e a modelagem molecular mostraram que a geometria adotada pelo centro metálico é a octaédrica distorcida. Para os ligantes fosfatados, a espectroscopia Raman, a modelagem molecular e os cálculos teóricos indicaram que no complexo com a adenosina 5’-trifosfato a geometria deve ser octaédrica distorcida, com o ligante comportando-se como bidentado através dos átomos de oxigênio dos fosfatos terminais beta e gamma. Já no complexo com a fosfocreatina, a geometria deve ser tetraédrica distorcida, com o ligante comportando-se como tridentado coordenando-se pelos átomos de oxigênio do grupamento fosfato, de oxigênio do grupamento carboxilato e de nitrogênio do grupamento guanidino. Estes resultados mostram a variedade do comportamento dos ligantes na complexação com o Al(III). The study of binary complexes of Al(III) with sulfur amino acids (methionine, cysteine, homocysteine and penicillamine) and phosphate ligands (adenosine 5 - triphosphate and phosphocreatine) was done in aqueous solution applying potentiometric titrations, (13)C and (27)Al NMR, Raman spectroscopy, molecular modeling and DFT: B3LYP/6-311G theoretical calculations of the vibrational spectra. The potentiometric titrations and (13)C and (27)Al NMR were performed only for the complexes with amino acids. The potentiometry was used to determine the stability constants of the Al(III)-amino acid binary complexes and the distribution graphs of their species. The comparison between the values obtained for the constants revealed a distinct behavior for the Al-Penicillamine complex, with higher stability constants than the other complexes. It is suggested that penicillamine might act as a tridentate ligand through the oxygen of the carboxylate, the nitrogen of the amine and the sulfur of the sulfhydryl, while others act as bidentate ligands coordinating through the oxygen of the carboxylate and the nitrogen of the amine. The graphs of the species distribution in function of pH showed that in biological pH there is a predominance of hydrolyzed species of the metal and the complex. Raman and (13)C NMR spectroscopy associated with theoretical calculations confirmed the coordination sites proposed for the amino acids. (27)Al NMR and molecular modeling showed that the geometry adopted by the metal center is distorted octahedral. For phosphate ligands, Raman spectroscopy, molecular modeling and theoretical calculations indicated that the geometry of adenosine 5 - triphosphate complex can be distorted octahedral with the ligand behaving as bidentate through one oxygen atom of each terminal (beta) and (gamma) phosphates. Nevertheless, for the phosphocreatine complex the geometry seems to be a distorted tetrahedron with the ligand behaving as a tridentate, one coordinating through one of the oxygens in the phosphate, the oxygen in the carboxylate and the nitrogen in the guanidine group. These results bring to light the multiplicity of ligand behaviors in the complexation with Al(III).
- Published
- 2010
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