Abstract:Existe grande interesse no estudo de heterodímeros constituídos por metaloporfirinas e ftalocianinas de carga oposta, uma vez que estes sistemas são modelos do special pair da fotossíntese e dispositivos moleculares promissores para a transferência de elétrons unidirecional. Neste trabalho foram sintetizadas novas metaloporfirinas catiônicas, e investigada a formação de heteroagregados com metaloftalocianinas aniônicas em DMSO. Estes novos derivados porfirínicos catiônicos apresentam grupos benzílicos ligados … Show more
“…These protons are not present in the 1 H NMR spectrum [Zn(TMtPP)] due to the presence of Zn in the center of porphyrin. The elemental analysis results are in agreement with the fact that porphyrins are isolated as hydrates [23] . Mass spectral data gave expected molecular ion peaks and other fragments.…”
Section: Resultssupporting
confidence: 86%
“…The elemental analysis results are in agreement with the fact that porphyrins are isolated as hydrates. [23] Mass spectral data gave expected molecular ion peaks and other fragments.…”
Section: Characterization Of Free Base Porphyrin and Metal Complexesmentioning
In this work, we present Zn, CoII, and MnIII metalated meso‐tetra‐[4‐(methylthio) phenyl] porphyrin ([Zn(TMtPP)], [CoII(TMtPP], and [MnIII(TMtPP)Cl]) as electrocatalysts and photoelectrocatalysts for electrochemical detection and photoelectrocatalytic degradation of pentachlorophenol (PCP). The complexes were characterized using UV‐visible spectroscopy, mass spectroscopy, and elemental analysis. Proton nuclear magnetic resonance (1H NMR) studies were only conducted for the Zn derivative. The electrochemical detection of PCP was carried out using cyclic voltammetry and chronoamperometry. [CoII(TMtPP)] showed better detection limit. For photoelectrocatalytic (PEC) degradation studies of PCP, linear sweep voltammetry and UV‐visible spectra were employed. [Zn(TMtPP)] showed better removal efficiency. The main species responsible for the PEC degradation were found to be superoxide radicals (⋅O2) and electron holes (h+).
“…These protons are not present in the 1 H NMR spectrum [Zn(TMtPP)] due to the presence of Zn in the center of porphyrin. The elemental analysis results are in agreement with the fact that porphyrins are isolated as hydrates [23] . Mass spectral data gave expected molecular ion peaks and other fragments.…”
Section: Resultssupporting
confidence: 86%
“…The elemental analysis results are in agreement with the fact that porphyrins are isolated as hydrates. [23] Mass spectral data gave expected molecular ion peaks and other fragments.…”
Section: Characterization Of Free Base Porphyrin and Metal Complexesmentioning
In this work, we present Zn, CoII, and MnIII metalated meso‐tetra‐[4‐(methylthio) phenyl] porphyrin ([Zn(TMtPP)], [CoII(TMtPP], and [MnIII(TMtPP)Cl]) as electrocatalysts and photoelectrocatalysts for electrochemical detection and photoelectrocatalytic degradation of pentachlorophenol (PCP). The complexes were characterized using UV‐visible spectroscopy, mass spectroscopy, and elemental analysis. Proton nuclear magnetic resonance (1H NMR) studies were only conducted for the Zn derivative. The electrochemical detection of PCP was carried out using cyclic voltammetry and chronoamperometry. [CoII(TMtPP)] showed better detection limit. For photoelectrocatalytic (PEC) degradation studies of PCP, linear sweep voltammetry and UV‐visible spectra were employed. [Zn(TMtPP)] showed better removal efficiency. The main species responsible for the PEC degradation were found to be superoxide radicals (⋅O2) and electron holes (h+).
“…The K b was then calculated from the ratio of the slope to the intercept. The binding stoichiometries were obtained by using the method of continuous variation, or Job plot [83,84]. Job diagrams were obtained by plotting F(χ) against the molar fraction of the ligand (χ) at each point of the titration, according to the following equation:…”
Since the occurrence of tumours is closely associated with the telomerase function and oncogene expression, the structure of such enzymes and genes are being recognized as targets for new anticancer drugs. The efficacy of several ligands in telomerase inhibition and in the regulation of genes expression, by an effective stabilisation of G-quadruplexes (G4) DNA structures, is being considered as a promising strategy in cancer therapies. When evaluating the potential of a ligand for telomerase inhibition, the selectivity towards quadruplex versus duplex DNA is a fundamental attribute due to the large amount of double-stranded DNA in the cellular nucleus. This study reports the evaluated efficacy of three tetracationic opp-dibenzoporphyrins, a free base, and the corresponding zinc(II) and nickel(II) complexes, to stabilise G4 structures, namely the telomeric DNA sequence (AG3(T2AG3)3). In order to evaluate the selectivity of these ligands towards G4 structures, their interaction towards DNA calf thymus, as a double-strand DNA sequence, were also studied. The data obtained by using different spectroscopic techniques, such as ultraviolet-visible, fluorescence, and circular dichroism, suggested good affinity of the free-base porphyrin and of its zinc(II) complex for the considered DNA structures, both showing a pattern of selectivity for the telomeric G4 structure. A pattern of aggregation in aqueous solution was detected for both Zn(II) and Ni(II) metallo dibenzoporphyrins and the ability of DNA sequences to induce ligand disaggregation was observed.
“…Quando esta tendência natural é realçada por interações eletrostáticas [62,116,117], os sistemas obtidos tendem a ser bastante estáveis, mantendo as propriedades observadas em solução. Desse modo, esses sistemas respondem bem aos dois primeiros requisitos.…”
“…A estequiometria do par iônico foi determinada pelo método de Job [117,202,203]. equivale a absorvância medida após a adição de cada alíquota do titulante em um dado comprimento de onda, C P c e C P correspondem a concentração total da ftalociona e das respectivas supermoléculas, ǫ P c e ǫ P são a absortividade molar da ftalocianina e da respectiva supermolécula no comprimento de onda considerado para A exp.…”
Ao CNPq, pela bolsa de doutorado. Aos membros da banca por terem prestigiado este trabalho participando da defesa e pelas críticas enriquecedoras. Ao Prof. Marcos Eberlin e a Dra. Daniela Tomazela, do Instituto de Química da Unicamp, pela medida dos espectros de massa. À Miriam Uemi, da central analítica do IQ, pela colaboração com os espectros de RMN de platina. Aos amigos Juliano e Sérgio pela grande força que me deram na reta final deste trabalho e pela colaboração com os dados de SPR. Formiga e Marcelo pela colaboração com os dados de modelagem molecular e microscopia. Ronaldo, pelas conversas sempre ricas em informação e pela revisão do texto. Genebaldo pelo incentivo. A todos vocês agradeço principalmente pela grande amizade e companheirismo. À Aninha pelo convívio nestes anos de laboratório e pelo suporte prestado no nosso dia-a-dia de experimentos. Ao Prof. Koiti e a todos os colegas de diferentes gerações do LQSN como Herbert, Ildemar e Fauze, com quem tive o prazer de conviver e muito aprender nesses últimos anos. Aos amigos de sempre Paulo Lima, Adriano Oliveira e tantos outros que eu poderia citar, mas que apenas me limito para não me estender demais, pela amizade e incentivo. Finalmente, a todos aqueles que de alguma forma contribuíram para que esta tese se tornasse realidade, meu profundo agradecimento.
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