Ynara Marina Idemori

Bio: Ynara Marina Idemori is an academic researcher from Universidade Federal de Minas Gerais. The author has contributed to research in topics: Porphyrin & Cyclohexanol. The author has an hindex of 20, co-authored 40 publications receiving 1062 citations.

Multiple magnetic characteristics in pure and Mn porphyrin-doped single-walled carbon nanotubes

Abstract: Magnetism of single-walled carbon nanotubes (SWCNT) is probed and an unexpected multiple magnetic behavior is observed. Paramagnetism, diamagnetism, and ferro(antiferro)magnetism in superparamagnetic form are present in 99.9 % pure samples. A paramagnetic component and a diamagnetic component, both present in the whole magnetic field range, add up to form a net diamagnetism, as expected. Moreover, antiferromagnetism is present. By contrast, a Mn(III)-porphyrin/SWCNT nanocomposite shows a different behavior. The SWCNT net diamagnetism vanishes, and spin-glass (spin-canted) behavior is observed. A de Almeida–Thouless line fit is used to verify the existence of the spin-glass state. Thermogravimetric analysis, along with electron spin resonance and energy dispersive spectrometry indicates that the amount of residual catalyst nanoparticles <1 % wt. left from the synthesis of SWCNT is unable to explain the magnetic behavior observed. Theoretical works are used to explain the phenomena.

Metalloporphyrins immobilized on silica-coated Fe3O4 nanoparticles: Magnetically recoverable catalysts for the oxidation of organic substrates

Abstract: In this paper we report the immobilization of different cationic and neutral metalloporphyrins (MPs) on silica-coated Fe 3 O 4 nanoparticles, obtained by basic hydrolytic sol–gel process. We characterized the MP-immobilized materials by UV–vis spectroscopy (UV–vis), X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). We achieved 100% and 2% immobilization of cationic and neutral MPs, respectively. The strong electrostatic interactions between the hydroxylated surface of the silica and the positive charges of the cationic MPs favored immobilization of the charged MPs; the neutral MP probably established a weak bond with the silica and easily leached from the support. We investigated the catalytic activity of the immobilized MPs in the oxidation of cyclooctene, cyclohexene, and cyclohexane using iodosylbenzene as oxygen donor. We used the immobilized MPs in at least five successive cyclooctene oxidation reactions – the yields did not decrease, confirming that the catalyst can be reused. The synthesized catalysts displayed magnetic properties, which allowed their fast separation from the reaction medium using a simple magnet.

Cationic iroporphyrins as catalyst in comparative oxidation of hydrocarbons: homogeneous and supported on inorganic matrices systems

Abstract: Cationic ironporphyrins in solution and supported on imidazole propyl gel (IPG) and silica gel (SG) as catalyst in cyclohexane hydroxylation using iodosylarene as oxygen donor were studied. FeTM4PyP 5+ , 1 as homogeneous catalyst for cyclohexane hydroxylation, in acetonitrile (CH 3 CN) and ultrasound stirring, gives cyclohexanol (C-ol) yields of 20%. The FeTM2PyP 5+ , 2 as catalyst for cyclohexene oxidation in CH 3 CN and ultrasound stirring is a very efficient system, giving 93% of total yield, with an epoxide:alcohol:ketone selectivity of 77:12:11. The supported systems, 1 -IPG and 1 -SG are particularly efficient in dichloromethane (CH 2 Cl 2 ), giving C-ol yields of 37% and 53%, respectively. These systems consist of polar hemin in isolated sites, which selectively catalyze cyclohexane oxidation in apolar solvent. They represent good cytochrome P-450 model systems. In the same way, the active site of P-450 consists of a polar protohemin in a hydrophobic pocket, promoting selective cyclohexane oxidation. These rigid cationic 1 -IPG, 1 -SG, 2 -IPG, 2 -SG, 3 -IPG and 3 -SG systems can catalyze with very small amounts of ironporphyrins, which correspond to about 30–80 times fewer numbers than the hemin in P-450 catalytic site.

Chemistry of Polyvalent Iodine

Abstract: Starting from the early 1990’s, the chemistry of polyvalent iodine organic compounds has experienced an explosive development. This surging interest in iodine compounds is mainly due to the very useful oxidizing properties of polyvalent organic iodine reagents, combined with their benign environmental character and commercial availability. Iodine(III) and iodine(V) derivatives are now routinely used in organic synthesis as reagents for various selective oxidative transformations of complex organic molecules. Several areas of hypervalent organoiodine chemistry have recently attracted especially active interest and research activity. These areas, in particular, include the synthetic applications of 2-iodoxybenzoic acid (IBX) and similar oxidizing reagents based on the iodine(V) derivatives, the development and synthetic use of polymer-supported and recyclable polyvalent iodine reagents, the catalytic applications of organoiodine compounds, and structural studies of complexes and supramolecular assemblies of polyvalent iodine compounds. The chemistry of polyvalent iodine has previously been covered in four books1–4 and several comprehensive review papers.5–17 Numerous reviews on specific classes of polyvalent iodine compounds and their synthetic applications have recently been published.18–61 Most notable are the specialized reviews on [hydroxy(tosyloxy)iodo]benzene,41 the chemistry and synthetic applications of iodonium salts,29,36,38,42,43,46,47,54,55 the chemistry of iodonium ylides,56–58 the chemistry of iminoiodanes,28 hypervalent iodine fluorides,27 electrophilic perfluoroalkylations,44 perfluoroorgano hypervalent iodine compounds,61 the chemistry of benziodoxoles,24,45 polymer-supported hypervalent iodine reagents,30 hypervalent iodine-mediated ring contraction reactions,21 application of hypervalent iodine in the synthesis of heterocycles,25,40 application of hypervalent iodine in the oxidation of phenolic compounds,32,34,50–53,60 oxidation of carbonyl compounds with organohypervalent iodine reagents,37 application of hypervalent iodine in (hetero)biaryl coupling reactions,31 phosphorolytic reactivity of o-iodosylcarboxylates,33 coordination of hypervalent iodine,19 transition metal catalyzed reactions of hypervalent iodine compounds,18 radical reactions of hypervalent iodine,35,39 stereoselective reactions of hypervalent iodine electrophiles,48 catalytic applications of organoiodine compounds,20,49 and synthetic applications of pentavalent iodine reagents.22,23,26,59 The main purpose of the present review is to summarize the data that appeared in the literature following publication of our previous reviews in 1996 and 2002. In addition, a brief introductory discussion of the most important earlier works is provided in each section. The review is organized according to the classes of organic polyvalent iodine compounds with emphasis on their synthetic application. Literature coverage is through July 2008.

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Abstract: The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...