Solid-state structural studies on amorphous platinum–fullerene[60] compounds [PtnC60]

Herbst, Marcelo H.; Pinhal, Nelson M.; Demétrio, Fábio A.T.; Dias, Gilson H. M.; Vugman, N.V.

doi:10.1016/s0022-3093(00)00229-5

Cited by 11 publications

(12 citation statements)

References 8 publications

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“…According to our hypothesis, this suggests that control-melanin has more self-interaction sites as well as interaction sites for associated structures and therefore is more compact. As indicated by Herbst et al [ 29 ], the profile of progressive microwave power saturation curves of amorphous solids is linked to the effectiveness of spin relaxation pathways for the paramagnetic centre that interacts with its surroundings. Hence, the measure of the progressive microwave power saturation curves for similar paramagnetic centres may provide an indirect indication of molecular arrangements.…”

Section: Discussionmentioning

confidence: 99%

Melanin in Fonsecaea pedrosoi: a trap for oxidative radicals

et al. 2010

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BackgroundThe pathogenic fungus Fonsecaea pedrosoi constitutively produces the pigment melanin, an important virulence factor in fungi. Melanin is incorporated in the cell wall structure and provides chemical and physical protection for the fungus.We evaluated the production of nitric oxide (NO) in macrophages, the oxidative burst and the inducible nitric oxide synthase (i-NOS) activity in interactions between activated murine macrophages and F. pedrosoi. Experiments were carried out with or without tricyclazole (TC) treatment, a selective inhibitor of the dihydroxynaphthalene (DHN)-melanin biosynthesis pathway in F. pedrosoi. The paramagnetisms of melanin and the TC-melanin were analysed by electron spin resonance. The fungal growth responses to H2O2 and to S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide donor, were also evaluated.ResultsMelanised F. pedrosoi cells were more resistant to both H2O2 and NO. Nitrite was not detected in the supernatant of macrophages incubated with melanised fungal cells. However, i-NOS expression was unaffected by the presence of either untreated control F. pedrosoi or TC-treated F. pedrosoi. In addition, the inhibition of the DHN-melanin pathway by TC improved the oxidative burst capability of the macrophages.ConclusionThe NO-trapping ability of F. pedrosoi melanin is an important mechanism to escape the oxidative burst of macrophages.

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Section: Discussionmentioning

confidence: 99%

Melanin in Fonsecaea pedrosoi: a trap for oxidative radicals

et al. 2010

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“…These polymers were formed via reaction of fullerene with dibenzylideneacetone (dba) complexes of Pt(0), Pt(dba) 2 , and Pd(0), Pd 2 (dba) 3 CHCl 3 . The poly-Pt n C 60 polymer was also produced via reaction of C 60 with Pt(1,5-cyclooctadiene) 2 . A carbonyl complex Ru 3 (CO) 12 was used to synthesize poly-Ru 3 C 60 .…”

Section: Formation and Structure Of Two-component Polymers With C60 A...mentioning

confidence: 99%

“…The polymer is deposited in the form of large cubic structures that are composed of nanometer-size spherical particles (Figure ). The polymers of C 60 and platinum can be also formed using low-valent Pt(1,5-cyclooctadiene) 2 in the synthesis …”

Section: Formation and Structure Of Two-component Polymers With C60 A...mentioning

confidence: 99%

Two-Component Polymeric Materials of Fullerenes and the Transition Metal Complexes: A Bridge between Metal–Organic Frameworks and Conducting Polymers

2016

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In this review, we examined the interactions of metal complexes and metal surfaces with fullerenes. That information has been related to the formation of redox-active materials produced by electrochemical reduction of solutions of various transition metal complexes and fullerene or fullerene adducts. These redox-active polymers are strongly bound to electrode surfaces and display electrochemical activity in solutions containing only supporting electrolyte. Extensive studies of the electrochemical behavior of these films have been used to characterize their properties and structure. The process that produces these poly-Pd(n)C60 and poly-Pt(n)C60 films can also produce composite materials that consist of metal nanoparticles interspersed with the poly-Pd(n)C60 and poly-Pt(n)C60 materials. The relationship between these redox-active films and conducting metal organic framework materials has been examined. These insoluble, redox-active polymers have potential utility for the adsorption of various gases, for the construction of capacitors, for sensing, for the preparation of metal-containing heterofullerenes, and for catalysis.

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“…Presumably, there is an interaction between platinum ions, which is also proved by the downfield shift of the line at 77 K. The line narrowing at 77 K is attributable to an increase in the spin3lattice relaxation time. We believe that Pt/FS comb contains platinum fullerides Pt n C 60 and Pt n C 70 in an amorphous state typical of them [19].…”

Section: äääääääääääämentioning

confidence: 89%

Platinized Fullerene Soots in the Synthesis of Fullerene-Containing Platinum Complexes

et al. 2005

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Thermal reaction of platinized fullerene soot and platinum(II) acetylacetonate occurs in the combustion mode. As shown by ESR, the combustion products contain compounds of platinum with fullerene.Water-soluble fullerene-containing platinum complexes with the parameters g eff = 2 and DH = 84 mT were synthesized by the hydroxylation of combustion products with a nitric acid solution.Carbon clusters, fullerenes and their compounds, have extremely wide spectrum of biological activity: antiviral, antimicrobial, and antitumor; they are active against HIV infection [13 4]. However, both fullerenes and overwhelming majority of their derivatives are insoluble in water, which makes them incompatible with physiological media and is one of the main obstacles in their use for biomedical purposes.Polyhydroxylated fullerenes C 60 (OH) x and C 70 (OH) x (fullerenols) are water-soluble [4 37] and biologically active [8] compounds. As a rule, fullerenes are isolated with a large number of hydroxy groups as a mixture of isomers. The number of hydroxy groups in C 60 (OH) x can reach 36. Recently the diols C 60 (OH) 2 and C 70 (OH) 2 were synthesized in the individual form [9]. Water-soluble metal-containing fullerenols were synthesized by the hydroxylation of endohedral fullerides C 82 of f metals (Gd, Ho, Pr) [10, 11], but they are poorly accessible for wide-scale studies because of the lack of efficient procedures for the synthesis of higher fullerenes and their endohedral complexes. The formation of exohedrally bound compounds with metals is characteristic for more readily accessible fullerenes, C 60 and C 70 . They are described in numerous papers, but no water-soluble compounds of this type were reported. Anions C 60 n3 were hydroxylated in lithium fullerides [12] to give fullerenol C 60 H 2 (OH) 24 readily soluble in water. It was interesting to carry out the hydroxylation of fullerides of d metals as a possible route to water-soluble fullerenecontaining complexes of metals.The aim of this work was to synthesize and study fullerene-containing platinum complexes. EXPERIMENTALPlatinized fullerene-containing soot (Pt/FS) [13] was the starting reagent. It was prepared in a plasmochemical reactor. Its operation is based on the vaporization of graphite under atmospheric pressure in an long plasma jet with a longitudinal (~1 m) temperature gradient from 5000 to 2000 K [14]. A metallic platinum powder was placed in the orifice of one of graphite electrodes between which the carbon plasma jet is formed. The reactor was cooled to room temperature. The resulting condensate (Pt/FS) contained approximately 8% of a mixture of fullerenes with the ratio C 60 /C 70 = 4/1 (the content of higher fullerenes in the fullerene mixture was less than 1%), approximately 5% of platinum in the form of finely dispersed metal particles, more than 80% of ultradispersed carbon not bound in fullerenes, and residual graphite [13].Pt/FS with an addition (about 33 4%) of platinum acetylacetonate Pt(acac) 2 1 was heated to initiate the combustion of the reagents....

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Solid-state structural studies on amorphous platinum–fullerene[60] compounds [PtnC60]

Cited by 11 publications

References 8 publications

Melanin in Fonsecaea pedrosoi: a trap for oxidative radicals

Melanin in Fonsecaea pedrosoi: a trap for oxidative radicals

Two-Component Polymeric Materials of Fullerenes and the Transition Metal Complexes: A Bridge between Metal–Organic Frameworks and Conducting Polymers

Platinized Fullerene Soots in the Synthesis of Fullerene-Containing Platinum Complexes

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