Archive for the ‘Hot Articles’ Category

Linking Porphyrins for Heterogeneous Catalysis

In this recent communication, W. Zhang and co-workers have demonstrated a novel way to form covalent porphyrinic frameworks (CPFs) using squaraine and hydrazine linkers. By using purely organic moieties the researchers have eliminated the need for metal nodes that are present in the more traditional porous coordination polymers.

Using the principles of supramolecular chemistry the authors have used a metallation process to introduce manganese, a well-known and abundant redox active transition metal, into the cavity of the porphyrin component of the framework. Thus, an easily accessible active site for redox catalysis was generated and subsequently demonstrated to be active for the selective oxidation of aliphatic molecules.

Interestingly, it was also shown that the choice of linker can have an effect on the resulting catalytic activity of these new materials. Preliminary characterisation showed a correlation between the extended conjugation of the organic framework, the state of the manganese and the activity/selectivity of the catalytic processes. This phenomenon, often observed in homogeneous porphyrin catalysts, has been elegantly incorporated into these heterogeneous analogues. One can hypothesise that in future, by careful design of the organic linkers joining the porphyrin units, it may be possible to fine-tune the material for different catalytic reactions.

To find out more, why not take a look at the article now?

Bottom-up approach to engineer two covalent porphyrinic frameworks as effective catalysts for selective oxidation

Weijie Zhang, Pingping Jiang, Ying Wang, Jian Zhang and Pingbo Zhang

Catal. Sci. Technol., 2015, DOI: 10.1039/C4CY00969J

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Unfogging metathesis catalyst deactivation

Grubbs catalyst deactivationD. Fogg et al. have discovered a powerful means to observe the behaviour of Grubbs metathesis catalysts.

The University of Ottawa researchers tagged first- and second-generation ruthenium catalysts with a 13C label at the alkylidene site using straightforward synthesis routes. This isotopic enrichment allowed 13C NMR spectroscopy to serve as a sensitive probe for the amine-initiated decomposition pathway.

A surprising preference for nucleophilic attack by phosphine was clearly revealed in the 13C NMR spectrum. This demonstrates the diagnostic utility of 13C-enriched complexes relative to both their unlabelled and deuterium-labelled analogues.

This article is featured amongst many other excellent contributions in the latest Catalysis Science & Technology themed issue, Mechanistic Studies in Catalysis.

Take a look at the original article online now!

Isotopic Probes for Ruthenium-Catalyzed Olefin Metathesis
Justin A. M. Lummiss, Adrian G. G. Botti, and Deryn E. Fogg*
Catal. Sci. Technol. 2014, Advance Article, DOI: 10.1039/C4CY01118J

Jenna Flogeras obtained her B.Sc. and M.Sc. in Chemistry from the University of New Brunswick (Fredericton), Canada. She is currently a Ph.D. student at Memorial University in Newfoundland, where she studies aluminum-based catalysts under the supervision of Dr. Francesca Kerton.

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Promising catalysts for carbon dioxide capture

A team of researchers at the University of Kentucky have developed highly active homogeneous catalysts for the capture of carbon dioxide in post-combustion processes. The complexes, based on zinc and cobalt metal centres, increase mass transfer by up to 34% in concentrated, aqueous solutions of primary amine.

Carbonic anhydrase metalloenzymes are known as the most active catalysts for the hydration of carbon dioxide under mild conditions. The catalysts reported here are inexpensive alternatives that can better tolerate the harsh conditions of industrial gas streams.

Read the full article online now:

K. Liu et al., Catal. Sci. Technol. 2014, Advance Article
DOI: 10.1039/C4CY00766B

Jenna Flogeras obtained her B.Sc. and M.Sc. in Chemistry from the University of New Brunswick (Fredericton), Canada. She is currently a Ph.D. student at Memorial University in Newfoundland, where she studies aluminum-based catalysts under the supervision of Dr. Francesca Kerton.
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HOT articles in Catalysis Science & Technology

Take a look at the selection which are free to read for a short time: Graphical abstract: Cu-MOFs as active, selective and reusable catalysts for oxidative C–O bond coupling reactions by direct C–H activation of formamides, aldehydes and ethers

NaF regulated aqueous phase synthesis of aromatic amides and imines catalyzed by Au/HT
Qianqian Wang, Youquan Deng and Feng Shi
DOI: 10.1039/C4CY00210E, Communication

Cu-MOFs as active, selective and reusable catalysts for oxidative C–O bond coupling reactions by direct C–H activation of formamides, aldehydes and ethers
I. Luz, A. Corma and F. X. Llabrés i Xamena
DOI: 10.1039/C4CY00032C, Paper

Recent developments in liquid-phase selective oxidation using environmentally benign oxidants and mesoporous metal silicates
Oxana A. Kholdeeva
DOI: 10.1039/C4CY00087K, Perspective

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HOT articles in Catalysis Science & Technology

Take a look at the selection which are free to read for a short time: Graphical abstract: Homogeneous catalysis for the conversion of biomass and biomass-derived platform chemicals

Homogeneous catalysis for the conversion of biomass and biomass-derived platform chemicals
Peter J. Deuss, Katalin Barta and Johannes G. de Vries
DOI: 10.1039/C3CY01058A, Perspective

Highly active Cr(III) catalysts for the reaction of CO2 with epoxides
Sait Elmas, Muhammad A. Subhani, Marcus Harrer, Walter Leitner, Jörg Sundermeyer and Thomas E. Müller
DOI: 10.1039/C3CY01087B, Paper

Regioselective transformation of alkynes catalyzed by a copper hydride or boryl copper species
Tetsuaki Fujihara, Kazuhiko Semba, Jun Terao and Yasushi Tsuji
DOI: 10.1039/C4CY00070F, Perspective

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Styrene carbonate synthesis by unsymmetrical aluminium catalyst

Reactions that utilize carbon dioxide are widely studied for their potential role in climate change mitigation. Symmetrical aluminium salen complexes are well known for their ability to catalyze reactions of carbon dioxide with epoxides, producing commercially valuable cyclic carbonates or polycarbonates. Aluminium complexes based on an unsymmetrical coordination environment, however, have not yet been explored for the cycloaddition reaction. This research represents the first catalyst study incorporating a hybrid salen-acetylacetonate ligand, using styrene oxide as a substrate.

The University of Sheffield researchers discovered that the catalyst achieves 70% conversion to styrene carbonate at atmospheric pressure and elevated temperatures. When used in conjunction with tetrabutylammonium bromide (TBAB) in dichloromethane, this value reaches 90%. Moreover, TBAB alone catalyzes the reaction in yields comparable to the aluminium catalyst.

The full paper can be read here:

A single centre aluminium(III) catalyst and TBAB as an ionic organo-catalyst for the homogeneous catalytic synthesis of styrene carbonate
Somsak Supasitmongkol and Peter Styring
Catal. Sci. Technol. 2014, Advance Article, DOI: 10.1039/C3CY01015E 

Jenna Flogeras obtained her B.Sc. and M.Sc. in Chemistry from the University of New Brunswick (Fredericton), Canada. She is currently working towards her Ph.D. at Memorial University of Newfoundland, under the supervision of Dr. Francesca Kerton. Her research is focused on the synthesis of biodegradable polymers using main-group metal complexes as catalysts.

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HOT articles for March

Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: a review
Sina Sartipi, Michiel Makkee, Freek Kapteijn and Jorge Gascon
Catal. Sci. Technol., 2014,4, 893-907
DOI: 10.1039/C3CY01021J

Graphical abstract

Free to access until 11th April 2014


Combining wet impregnation and dry sputtering to prepare highly-active CoPd/H-ZSM5 ternary catalysts applied for tandem catalytic synthesis of isoparaffins
Jian Sun, Wenqi Niu, Akira Taguchi, Takayuki Abe, Yoshiharu Yoneyama and Noritatsu Tsubaki  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY01091K

Graphical abstract

Free to access until 11th April 2014


Cooperation between the surface hydroxyl groups of Ru–SiO2@mSiO2 and water for good catalytic performance for hydrogenation of quinoline
Lei Zhang, Xiaoyan Wang, Ying Xue, Xiaojun Zeng, Hua Chen, Ruixiang Li and Shanling Wang  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY01071F

Graphical abstract

Free to access until 4th April 2014


Easily accessible bifunctional Zn(salpyr) catalysts for the formation of organic carbonates
C. Martín, C. J. Whiteoak, E. Martin, M. Martínez Belmonte, E. C. Escudero-Adán and A. W. Kleij
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY01043K

Graphical abstract

 

Free to access until 4th April 2014

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HOT articles for February

Alkali- and nitrate-free synthesis of highly active Mg–Al hydrotalcite-coated alumina for FAME production
Julia J. Creasey, Alessandro Chieregato, Jinesh C. Manayil, Christopher M. A. Parlett, Karen Wilson and Adam F. Lee  
Catal. Sci. Technol., 2014,4, 861-870
DOI: 10.1039/C3CY00902E

Graphical abstract

Free to access until 20th March 2014


Rearrangement of aldoximes to amides in water under air atmosphere catalyzed by water-soluble iridium complex [Cp*Ir(H2O)3][OTf]2
Chunlou Sun, Panpan Qu and Feng Li  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00934C

Graphical abstract

Free to access until 20th March 2014


Dimerization of ethene in a fluidized bed reactor using Ni-based Supported Ionic Liquid Phase (SILP) catalysts

Florian T. U. Kohler, Konstantin Gärtner, Veit Hager, Marco Haumann, Michelle Sternberg, Xinjiao Wang, Normen Szesni, Karsten Meyer and Peter Wasserscheid  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00905J

Graphical abstract

Free to access until 7th March 2014


Kinetic Monte Carlo simulations of heterogeneously catalyzed oxidation reactions
Franziska Hess and Herbert Over  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00833A

Graphical abstract

 

Free to access until 7th March 2014

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Nature leads the way: A Biomimetic Tricopper complex as a catalyst for selective oxidation of smaller alkanes

2014 has arrived and with it a new batches of Hot Articles, one of which from January deserves special attention. Professor Sunny Chan‘s group at Academia Sinica,  Taiwan have achieved the distinction of being the first group to devise a molecular catalyst for the selective oxidation of methane to methanol. This reaction faces a formidable challenge in the form of inertness of the methane C–H bond which makes O-atom insertion into the molecule almost impossible in ambient conditions.  Even if this problem is solved, the product, methanol, is highly susceptible to over-oxidation leading to formation of other undesired products. For of these reasons, most of the researchers have failed to scale this gargantuan mountain of difficulties.

Time and again when scientists have found it difficult to get answers to tough and challenging problems they have turned to nature for inspiration. In this case, the solution lay in a particular class of enzymes called methane monoxygenases (MMO) found in the methanotrophic bacteria. These MMOs have metallic clusters at their centres, which catalyse this difficult reaction with ease. In order to emulate these catalytic centres, the researchers developed some biomimetic models containing tricopper clusters, one of which, [CuICuICuI(7-N-Etppz)][ClO4], successfully mediated the selective oxidation of methane without any over-oxidation. This tricopper complex, when activated by dioxygen (O2), harnesses a “singlet oxene”, the strongest oxidant that could be used for a facile O-atom insertion across the C-H bond.

Biomimetic Tricopper complex as a catalyst for selective oxidation of methane to methanol

The catalyst also gave selectivity in the cases of ethane and propane, but not with higher alkanes. The reason being is the design of the tricopper catalyst, which has a small hydrophobic binding pocket at the base and forms a transient complex with the alkane and carries out the oxene transfer to oxidize the substrate. This pocket is not big enough to accommodate the product methanol (as well as the other small alcohols), so it releases the product as soon as it is formed. This removes over-oxidation from the equation, giving profound selectivity in cases of smaller alkanes. The authors have further studied the catalytic cycles and analysed the factors affecting the catalytic turnovers and efficiency.

This work presents a move towards a more efficient flow system which, in the future, would help in increasing the yields of the products. One issue with the current system is the solubility of the catalyst in solvents which can dissolve CH4 gas which may be put to rest by some modification in the design of the catalyst, leaving brighter prospects for the future.

To find out more about this nature-inspired discovery, read the full article now for more details.

Developing an efficient catalyst for controlled oxidation of small alkanes under ambient conditions
Penumaka Nagababu, Steve S.-F. Yu, Suman Maji, Ravirala Ramu and Sunney I. Chan
Catal. Sci. Technol., 2014, DOI: 10.1039/C3CY00884C


Shreesha Bhat, Web Writer Shreesha Bhat is a M.S.(Pharm.) in Medicinal Chemistry from National Institute  of  Pharmaceutical Education and Research,  India. He has recently joined the research group of  Dr. Pallavi Sharma as a PhD student at the  University of Lincoln, UK. His project involves  the design and synthesis of Helicase-primase inhibitors for Herpes Simplex virus and development of useful synthetic methodologies.

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HOT articles for January

Homogeneous catalytic reduction of CO2 with hydrosilanes
Francisco J. Fernández-Alvarez, Abdullah M. Aitani and Luis A. Oro  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00948C       

Graphical abstract

Free to access until 28th February 2014


CO2 photoreduction with H2O vapor by porous MgO–TiO2 microspheres: effects of surface MgO dispersion and CO2 adsorption–desorption dynamics
Lianjun Liu, Cunyu Zhao, Daniel Pitts, Huilei Zhao and Ying Li  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00807J     

Graphical abstract   

Free to access until 28th February 2014


Chromium(III) amine-bis(phenolate) complexes as catalysts for copolymerization of cyclohexene oxide and CO2
Hua Chen, Louise N. Dawe and Christopher M. Kozak  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/c3cy01002c

Graphical abstract

Free to access until 21st February 2014


Self-regeneration of three-way catalyst rhodium supported on La-containing ZrO2 in an oxidative atmosphere
Hisaya Kawabata, Yuki Koda, Hirosuke Sumida, Masahiko Shigetsu, Akihide Takami and Kei Inumaru  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00838J

Graphical abstract

Free to access until 17th February 2014


Developing an efficient catalyst for controlled oxidation of small alkanes under ambient conditions
Penumaka Nagababu, Steve S.-F. Yu, Suman Maji, Ravirala Ramu and Sunney I. Chan  
Catal. Sci. Technol., 2014, Advance Article
DOI: 10.1039/C3CY00884C

Graphical abstract

Free to access until 17th February 2014

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