Special Issue "Nano-catalysts and Nano-technologies for Green Organic Synthesis"
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A special issue of Molecules (ISSN 1420-3049).
Deadline for manuscript submissions: closed (30 April 2010)
Special Issue Editors
Guest Editor
Prof. Dr. Angelo Nacci
CNR ICCOM, Department of Chemistry, University of Bari, Via Orabona 4, 70126-Bari, Italy and Università degli Studi di Bari, Dipartimento di Chimica, 4, via Orabona, I-70126 Bari, Italy
E-Mail: nacci@chimica.uniba.it
Interests: organometallic reactions catalysed by metal colloids (mainly Pd and Cu); C-Cl bond activation; phosphine-free conditions; detoxification of chloroarenes; chemical fixation of CO2 and preparation of catalysts for green chemistry
Guest Editor
Dr. Nicola Cioffi
Università degli Studi di Bari, Dipartimento di Chimica, 4 via Orabona, I-70126 Bari, Italy
Website: http://www.chimica.uniba.it/cioffi
E-Mail: cioffi@chimica.uniba.it
Phone: +390805442019
Fax: +390805442026
Interests: sensors (gas-, pollutant- & vapour-sensors); catalysts for green chemistry; bio-analysis; mass spectrometry & proteomics research; antibacterial/bioactive nanomaterials
Special Issue Information
Dear Colleagues,
Transition-metal nanoparticles are attracting a great deal of attention in almost any scientific and technological field. An increasing interest is nowadays devoted to the high activity and selectivity of nanocatalysts which allow to develop greener and waste-minimized processes. In addition, nanoparticles are suitable catalysts for processes carried out in neoteric eco-friendly solvents (viz. ionic liquids, supercritical fluids, fluorous phases, water etc.). For these reasons, green chemistry can play a prominent role in guiding the development of nanotechnology to provide the maximum benefit of these products for society and the environment. This Special Issue of Molecules has the objective to present articles dealing with the use of nanocatalysts and/or nanotechnologies in a wide range of catalytic organic reactions, ranging from the traditional carbon-carbon or carbon-heteroatom bond forming reactions (e.g. Heck, Suzuki, Stille, Sonogashira, Ullmann, Glodberg and so on) to the more innovative synthetic approaches based on the green chemistry principles (atom-economy, dematerialization, energy saving, raw material diversification, green solvents etc.) such as for example detoxification of PCBs, fixation of CO2 and so on. Multidisciplinary studies providing a bird-view of the nanocatalyst features, including its development/synthesis and its analytical chemical & morphological characterization, as well as organic synthesis application and structure-performance level correlations, are strongly encouraged.
Nicola Cioffi, Ph. D.
Prof. Dr. Angelo Nacci
Guest Editors
Submission
All manuscripts should be submitted to
molecules@mdpi.com with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the
Instructions for Authors page.
Molecules is an international peer-reviewed Open Access monthly journal published by
MDPI.
Keywords
- catalysis in eco-friendly solvents
- ionic liquids
- green chemistry
- nanocatalysts
- analytical characterization of catalytic systems
Published Papers (11 papers)
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Received: 9 December 2009; in revised form: 28 January 2010 / Accepted: 29 January 2010 / Published: 2 February 2010
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Abstract: The CeO2 nanorods (CeNR) promote the oxidation of ethylbenzene (PhEt) and cyclohexene with t-BuOOH, at temperatures as low as 55 ºC. For both substrates the saturated C-H bonds are preferentially activated over the unsaturated ones. The catalyst seems fairly stable towards leaching phenomena. The liquid-phase oxidation catalysis may be associated with the Ce3+/Ce4+ inter-conversion in the one-electron redox processes mediating the formation of tert-butyl-(per)oxy radicals. CeNR is very effective in H2O2 disproportionation. Pre-treatment of CeNR with H2O2 or t-BuOOH prior to the catalytic reaction enhances the reaction rate of PhEt with t-BuOOH in comparison to CeNR. Textural characterization and spectroscopic studies suggest that catalytic activation is associated to defect sites.
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Received: 12 January 2010; in revised form: 2 March 2010 / Accepted: 23 March 2010 / Published: 25 March 2010
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Abstract: Since metal nanoparticles have a high surface-to-volume ratio and very active surface atoms, they are very attractive catalysts for a wide variety of organic and inorganic reactions, compared to bulk catalysts. Metal nanoparticles suspended in colloidal solutions and those adsorbed onto bulk supports have been used as catalysts for a wide variety of carbon-carbon bond formation reactions such as the Suzuki and Heck cross-coupling reactions. This review article highlights some of the latest advances in the application of noble metal nanoparticles as catalysts for these two industrially important classes of cross-coupling reactions. We will discuss several important advances in using metal nanocatalysts in Suzuki and Heck cross-coupling reactions such as investigations on the nanoparticle shape dependence on the catalytic activity, novel types of supported metal nanoparticles as nanocatalysts, and the use of bi-metallic, tri-metallic and multi-metallic nanoparticles as catalysts for the Suzuki and Heck cross-coupling reactions.
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Received: 31 March 2010; in revised form: 27 April 2010 / Accepted: 29 April 2010 / Published: 5 May 2010
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Abstract: Catalytic hydrogenation under mild conditions of olefins, unsaturated aldeydes and ketones, nitriles and nitroarenes was investigated, using a supported rhodium complex obtained by copolymerization of Rh(cod)(aaema) [cod: 1,5-cyclooctadiene, aaema–: deprotonated form of 2-(acetoacetoxy)ethyl methacrylate] with acrylamides. In particular, the hydrogenation reaction of halonitroarenes was carried out under 20 bar hydrogen pressure with ethanol as solvent at room temperature, in order to minimize hydro-dehalogenation. The yields in haloanilines ranged from 85% (bromoaniline) to 98% (chloroaniline).
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Received: 16 April 2010; in revised form: 6 May 2010 / Accepted: 11 May 2010 / Published: 12 May 2010
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Abstract: A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs) in ionic liquids (ILs) is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media and the use of palladium nanoparticles as reservoir for the catalytically active palladium species.
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Received: 13 April 2010; in revised form: 24 May 2010 / Accepted: 26 May 2010 / Published: 28 May 2010
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Abstract: The one-pot acid-catalysed conversion of mono/di/polysaccharides (inulin, xylan, cellobiose, sucrose, glucose, fructose, xylose) into 2-furfuraldehyde (FUR) or 5-hydroxymethylfurfural (HMF) in the presence of aluminium-containing mesoporous TUD-1 (denoted as Al-TUD-1, Si/Al = 21), at 170 ºC was investigated. Xylose gave 60% FUR yield after 6 h reaction; hexose-based mono/disaccharides gave less than 20% HMF yield; polysaccharides gave less than 20 wt % FUR or HMF yields after 6 h. For four consecutive 6 h batches of the xylose reaction in the presence of Al-TUD-1, the FUR yields achieved were similar, without significant changes in Si/Al ratio.
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Received: 10 May 2010; in revised form: 16 June 2010 / Accepted: 21 June 2010 / Published: 24 June 2010
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Abstract: Palladium nanoparticles have been electrochemically supported on zirconium oxide nanostructured powders and all the nanomaterials have been characterized by several analytical techniques. The Pd/ZrO2 nanocatalyst is demonstrated to be a very efficient catalyst in Heck, Ullmann, and Suzuki reactions of aryl halides in water. The catalyst efficiency is attributed to the stabilization of Pd nanophases provided by tetra(alkyl)- ammonium hydroxide, which behaves both as base and PTC (phase transfer catalyst) agent.
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Received: 30 May 2010; in revised form: 11 June 2010 / Accepted: 2 July 2010 / Published: 2 July 2010
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Abstract: The preparation of carbon nanotube (CNT)/PdO nanoparticles and graphene oxide (GO)/PdO nanoparticle hybrids via a general aqueous solution strategy is reported. The PdO nanoparticles are generated in situ on the CNTs and GO by a one-step “green” synthetic approach in aqueous Pd(NO3)2 solution under ambient conditions without adding any additional chemicals. The production of PdO is confirmed by energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. The morphologies of the resulting CNT/PdO and GO/PdO nanohybrids are characterized by transmission and/or scanning transmission electron microscopy. PdO nanoparticles with an average size of 2–3 nm in diameter are decorated evenly along the surfaces of CNTs and GO. This synthesis strategy is demonstrated to be compatible for 1) CNTs with different modifications, including pristine, oxidized, and polymer-functionalized CNTs; 2) different types of CNTs, including single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multiwalled carbon nanotubes (MWCNTs); and 3) different shapes of carbon materials, including tubular CNTs and planar GO. The as-prepared CNT/PdO and GO/PdO nanohybrids can be transformed into CNT/Pd and GO/Pd nanohybrids by reduction with NaBH4, and can then be used as a heterogeneous catalyst in the catalytic reduction of 4-nitrophenol.
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Received: 25 May 2010; in revised form: 30 June 2010 / Accepted: 5 July 2010 / Published: 8 July 2010
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Abstract: Modern chemical synthesis makes heavy use of different types of catalytic systems: homogeneous, heterogeneous and nano-sized. The latter – nano-sized catalysts – have given rise in the 21st century to a rapidly developing area of research encompassing several prospects and opportunities for new technologies. Catalytic reactions ensure high regio- and stereoselectivity of chemical transformations, as well as better yields and milder reaction conditions. In recent years several novel catalytic systems were developed for selective formation of carbon-heteroatom and carbon-carbon bonds. This review presents the achievements of our team in our studies on various types of catalysts containing metal nanoparticles: palladium-containing diblock copolymer micelles; soluble palladium-containing polymers; metallides on a support; polymeric metal salts and oxides; and, in addition, metal-free organic catalysts based on soluble polymers acting as nanoreactors. Representative examples are given and discussed in light of possible applications to solve important problems in modern organic synthesis.
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Received: 24 June 2010; in revised form: 8 July 2010 / Accepted: 12 July 2010 / Published: 20 July 2010
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Abstract: This article is an account of the work carried out in the authors’ laboratory illustrating the usefulness of dendrimer design for nanoparticle palladium catalysis. The “click” synthesis of dendrimers constructed generation by generation by 1à3 C connectivity, introduces 1,2,3-triazolyl ligands insides the dendrimers at each generation. Complexation of the ligands by PdII followed by reduction to Pd0 forms dendrimer-stabilized Pd nanoparticles (PdNPs) that are extremely reactive in the catalysis of olefin hydrogenation and C-C bond coupling reactions. The stabilization can be outer-dendritic for the small zeroth-generation dendrimer or intra-dendritic for the larger first- and second-generation dendrimers. The example of the Miyaura-Suzuki reaction that can be catalyzed by down to 1 ppm of PdNPs with a “homeopathic” mechanism (the less, the better) is illustrated here, including catalysis in aqueous solvents.
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Received: 25 December 2010; in revised form: 6 January 2011 / Accepted: 7 January 2011 / Published: 7 January 2011
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Abstract: In the present work, a microchannel reactor for autothermal reforming of methanol using a synthesized catalyst porous alumina support-CuO/ZnO mixed with ZrO2 sol washcoat has been developed and its fine structure and inner surface characterized. Experimentally, CuO/ZnO and alumina support with ZrO2 sol washcoat catalyst (catalyst slurries) nanoparticles is the catalytically active component of the microreactor. Catalyst slurries have been dried at 298 K for 5 h and then calcined at 623 K for 2 h to increase the surface area and specific pore structures of the washcoat catalyst. The surface area of BET N2 adsorption isotherms for the as-synthesized catalyst and catalyst/ZrO2 sol washcoat samples are 62 and 108 ± 2 m2g−1, respectively. The intensities of Cu content from XRD and XPS data indicate that Al2O3 with Cu species to form CuAl2O4. The EXAFS data reveals that the Cu species in washcoat samples have Cu-O bonding with a bond distance of 1.88 ± 0.02 Å and the coordination number is 3.46 ± 0.05, respectively. Moreover, a hydrogen production rate of 2.16 L h−1 is obtained and the corresponding methanol conversion is 98% at 543 K using the CuO/ZnO with ZrO2 sol washcoat catalyst.
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Received: 8 April 2013; in revised form: 14 May 2013 / Accepted: 15 May 2013 / Published: 21 May 2013
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Abstract: The synthesis of nanoparticles has become a matter of great interest in recent times due to their various advantageous properties and applications in a variety of fields. The exploitation of different plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. In this study, iron oxide nanoparticles (Fe3O4-NPs) were synthesized using a rapid, single step and completely green biosynthetic method by reduction of ferric chloride solution with brown seaweed (BS, Sargassum muticum) water extract containing sulphated polysaccharides as a main factor which acts as reducing agent and efficient stabilizer. The structural and properties of the Fe3O4-NPs were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), vibrating sample magnetometry (VSM) and transmission electron microscopy. The average particle diameter as determined by TEM was found to be 18 ± 4 nm. X-ray diffraction showed that the nanoparticles are crystalline in nature, with a cubic shape. The nanoparticles synthesized through this biosynthesis method can potentially useful in various applications.
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Last update: 20 July 2010
