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A plethora of strategies for immobilizing well-defined metathesis catalysts on solid supports have been developed over the past decades. Whereas most reviews on classical heterogeneous metathesis catalyst designs mainly discuss covalent binding approaches, we here extended this topic with non-covalent surface science methods, a research area that gained interest recently. Within this context, the main focus was set on the immobilization of ruthenium alkylidenes or so-called Grubbs complexes, as these catalysts are known for their high activity, stability and commercial viability. Besides giving an overview of different immobilization strategies, the wide diversity of supported Grubbs catalysts also allows for discussing implications of attaching Grubbs catalysts that go beyond the traditional benefits of heterogeneous catalysis, such as easy catalyst separation. More specifically, this Review will summarize several unique opportunities of immobilized homogeneous catalysts in liquid-phase metathesis transformations in terms of impact on activity, stability, and product selectivity, as to highlight the economic potential, but without ignoring possible shortcomings and limitations.

A Ni catalytic system was developed for the decarboxylative coupling reaction of alkynyl carboxylic acids with organosilanes. Ni(acac)2 and 1,10-phenanthroline showed the best result in the presence of CsF and CuF2 at 120 °C. This system tolerated the presence of alkyl, alkoxy, halogen, nitro, cyano, ketone, and ester functional groups. Moreover, the reaction with but-2-ynedioic acid and organosilane afforded the corresponding symmetrical diarylalkynes.

The method is applied in the construction of compound (VI), a key intermediate in the total synthesis of (.+-.)-triptolide (VII).

In this review, we have portrayed the structure, synthesis and applications of a variety of biomimetic MOFs from an unprecedented angle. Synthetic MOF analogues of five distinct enzymes: phosphotriesterase, hydrogenase, cytochrome P450, chymotrypsin and carbonic anhydrase, have been discussed with their skeletal comparison to actual enzymatic active sites as reference, and an explanation of catalytic pathways from the mechanistic cycle of the corresponding enzymes is depicted. We demonstrated critically each of the five discrete situations by assimilating available benchmark researches in an attempt to provide a concise literature source on the ingenious design strategies and versatile biomimetic applications of this domain of materials.

Valuable information about the local environment of the aluminum nucleus can be obtained through 27 Al Nuclear Magnetic Resonance (NMR) parameters like the isotropic chemical shift, scalar and quadrupolar coupling constants, and relaxation rate. With nearly 250 scientific articles per year dealing with 27 Al NMR spectroscopy, this analytical tool has become popular because of the recent progress that has made the acquisition and interpretation of the NMR data much easier. The application of 27 Al NMR techniques to various classes of compounds, either in solution or solid-state, has been shown to be extremely informative concerning local structure and chemistry of aluminum in its various environments. The development of experimental methodologies combined with theoretical approaches and modeling has contributed to major advances in spectroscopic characterization especially in materials sciences where long-range periodicity and classical local NMR probes are lacking. In this review we will present an overview of results obtained by 27 Al NMR as well as the most relevant methodological developments over the last 25 years, concerning particularly on progress in the application of liquid- and solid-state 27 Al NMR to the study of aluminum-based materials such as aluminum polyoxoanions, zeolites, aluminophosphates, and metal-organic-frameworks.

Six new polyketide derivatives, including pestalpolyol I (1), pestapyrones A (2) and B (3), (R)-periplanetin D (6), pestaxanthone (7), norpestaphthalide A (8), and an isolation artifact pestapyrone C (4), were obtained from extracts of the endophytic fungus Pestalotiopsis clavispora isolated from the Mangrove plant Rhizophora harrisonii. In addition, seven known metabolites, including similanpyrone B (5), (R,S)-5,7-dihydroxy-3-(1-hydroxyethyl)phthalide (9), for which we propose the trivial name norpestaphthalide B, pestaphthalides A (10) and B (11), 2-epi-herbarumin II (12), and pestalotiollides A (13) and B (14) were isolated. The structures of the new compounds were unambiguously elucidated on the basis of one- and two-dimensional NMR spectroscopy, as well as by high-resolution mass spectrometry. All compounds were tested for their cytotoxicity against the mouse lymphoma cell line L5178Y. Compound 1 exhibited strong activity with an IC50 value of 4.10 μM. All other compounds (2–14) proved to be inactive (IC50 >10 μM) in this assay.

Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98% isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products.

A general approach to 2-substituted ethyl 5-aminothiazole-4-carboxylates is reported herein. Both aliphatic and aromatic thioamides undergo 1,2-addition to ethyl glyoxylate to give hemiaminals which, when treated with acetyl chloride, undergo elimination to the corresponding imines. Upon exposure to aqueous sodium cyanide the imines undergo a Strecker addition–cyclization reaction to provide the target heterocycles in modest to good yields over the 3-step process.

Recently, a class of dehydrogenative transformations for amide bond formation have been developed. These transformations are atom-economic and environmentally-benign processes with their respective starting materials of alcohols and amines, aldehydes and amines, as well as symmetrical esters and amines, showing a promising prospect for applications. These unique protocols have been reported using various ruthenium-based catalytic systems. However, challenges still exist in this area. For example, existing catalytic systems usually suffer from low efficiency, high catalyst loading, and lack of structural diversity.

Transparent colorless crystals of the title compounds are prepared from of solutions of Na3[C6N9] and RbF or CsF in boiling water by slow evaporation at room temperature.

Self-assembly is a potent synthetic tool that allowed chemists to design numerous complex structures, supramolecules of various shapes from relatively simple starting materials. Metal–organic polyhedra are a rising and promising member of the self-assembled supramolecule family possessing fascinating structures and functionalities directly deriving from the precursor units. During the last two decades, research in this field has been briskly progressed and it is now objective to exemplify various applications such as biomedical, catalysis, molecular sensing, gas adsorption and separation, and synthesis of metal–organic frameworks from polyhedra. This review will be focus on each and every application with various unprecedented examples and highlight few challenges still need to be address.

Colorless, transparent, very fragile, and extremely hygroscopic thin rectangular plates of LiK2[SCN]3 are obtained in adhering drops of 1:2, 1:1, or 2:1 molar mixtures of Li[SCN] and K[SCN] in abs.

The bulky, but symmetrically beautiful, adamantane ring system is now pervasive throughout physical, medicinal and synthetic chemistry, since it was first discovered in 1924 and coined “dekaterpene”. This fascinating name lived up to its natural product roots when adamantane was isolated from crude oil in 1933, but it was not until 1957 in a landmark contribution by Paul von Rague Schleyer that adamantane was made readily accessible through synthesis. Beyond the legacy to physical and medicinal chemistry, the adamantane moiety has been quintessential in the development of some of the most important catalysts to date. Considering adamantane’s impact on catalyst development past, present and future, this subject is for the first time reviewed herein.

This study demonstrates the ability of ammonium uranyl peroxide nanoclusters U32R-NH4 to undergo exchange in between NH4+ and trivalent (Nd3+) or tetravalent (Th4+) cations in the solid state. It paves the way for new promising routes for the synthesis of mixed uranyl peroxides. The exchange ability may also be considered for solution decontamination and synthesis of new mixed actinide-oxide precursors. Both of these applications could be used in the nuclear industry.

Active transition–metal complexes based on relatively inexpensive metals are considered to be a desirable method for sustainable human industrial growth. Considering their cost efficiency, ruthenium complexes are gaining increasing attraction, instead of palladium, rhodium, and iridium. Among the ruthenium complexes, ruthenium pincer complexes (RPCs) have received much attention due to their outstanding performance. Various strategies have been developed for pincer ligand design and RPC synthesis, which indicate that ligand design is a key feature of pincer chemistry. In addition, electronic and steric effects, hemilability, non-innocent behavior, and the flexibility of the pincer ligand have significant effects on the catalytic performance of RPCs in hydrogenation and dehydrogenation reactions.

Discrete metal-carboxylate cage-like materials are an important class of metal-organic polyhedra. The designs of these self-assemblies in terms of their characteristic polygonal shape, surface area, and related properties are functions of metal centers and carboxylate bridging linkers. Thus, several combinations of different metal ions with angular, linear ditopic, or tritopic carboxylic links can be integrated to map these nanoscale materials, as well as the optional functional groups for the ligands. Synthetic protocols based on variations in the solvent, temperature, and pressure can be employed to achieve metal-carboxylate self-organization. These types of discrete polyhedral nanocages with an internal void are materials with a broad spectrum of potential future uses as substrates for extended networks and highly selective gas sorbents in catalysis and biomedical processes.

Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS2 will be discussed. MoS2-based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important.

Single crystals of the title compound are synthesized from mixtures of the corresponding metals and NaN3 in molten Na (Na:Ge:Ga:Ca:Li = 13:1:1:0.5:0.5, 760 °C, 48 h).

Novel catalytic materials are highly demanded to perform a variety of catalytic organic reactions. MOFs combine the benefits of heterogeneous catalysis like easy post reaction separation, catalyst reusability, high stability and homogeneous catalysis such as high efficiency, selectivity, controllability and mild reaction conditions. The possible organization of active centers like metallic nodes, organic linkers, and their chemical synthetic functionalization on the nanoscale shows potential to build up MOFs particularly modified for catalytic challenges. In this review, we have summarized the recent research progress in heterogeneous catalysis by MOFs and their catalytic behavior in various organic reactions, highlighting the key features of MOFs as catalysts based on the active sites in the framework. Examples of their post functionalization, inclusion of active guest species and metal nanoparticles have been discussed. Finally, the use of MOFs as catalysts for asymmetric heterogeneous catalysis and stability of MOFs has been presented as separate sections.

2,5-Diaryl-substituted furans were synthesized from the copper-catalyzed decarboxylative coupling of aryl-substituted aryl propiolic acids in the presence of H2O. The homocoupling of alkynyl carboxylic acids provided 1,4-diaryldiynes, which then reacted with H2O to give the desired furans through cyclization. Addition of the copper catalyst was critical, and the addition of a ligand increased the yield of products in both the homocoupling and cyclization reactions. In addition, thiophenes could be obtained when the reaction was conducted in the presence of Na2S.

Olefin metathesis is a transition metal-mediated transformation that rearranges the carbon atoms of the carbon–carbon double bond of olefins. This reaction has become one of the most important and powerful reactions. Therefore development of new, well-defined, highly active and selective catalysts is very desirable and a valuable goal. This mini-review mainly introduces the development of ruthenium catalysts in olefin metathesis highlighting oxygen-chelated indenylidene ruthenium catalysts. Applying an alkoxyl group on the indenylidene ligand fragment can generate the RuO chelating bond. Additionally, various modifications of the ligand as well as the catalytic activity for ring-closing metathesis reaction and selectivity of cross metathesis reaction are overviewed. Finally, the perspectives on the development of new catalysts are summarized. Copyright © 2015 John Wiley & Sons, Ltd.

Photoredox catalysis with the use of a stable, reusable silica-bound chromophore was applied to the intramolecular cyclization of a series of 2-benzylidenehydrazinecarbothioamides to give 5-phenyl-1,3,4-thiadiazol-2-amines. The catalyst was readily prepared by carbodiimide-mediated coupling of commercially available amine-functionalized silica beads to a carboxylic acid functionalized ruthenium complex. The immobilized catalyst was readily removed from the reaction product by filtration and was used eight times without loss of catalytic activity. This simple, safe, and practical method is an attractive alternative to conventional procedures.

Given the important agricultural and medicinal application of optically pure heterocycles bearing a trifluoromethyl group at the stereogenic carbon center in the heterocyclic framework, the exploration of efficient and practical synthetic strategies to such types of molecules remains highly desirable. Catalytic enantioselective synthesis has one clear advantage that it is more cost-effective than other synthetic methods, but remains limited by challenges in achieving excellent yield and stereoselectivities with a low catalyst loading. Thus far, numerous models of organo- and organometal-catalyzed asymmetric reactions have been exploited to achieve this elusive goal over the past decade. This review article describes recent progress on this research topic, and focuses on an understanding of the catalytic asymmetric protocols exemplified in the catalytic enantioselective synthesis of a wide range of complex enantioenriched trifluoromethylated heterocycles.

An unexpected cyclotrimerization of aldehydes is observed at low temperature in the presence of water to form 1,3,5-trioxanes (II) in good yields.

Single crystals of KCs[N(CN)2]2 (I) and NaRb2[N(CN)2]3·H2O (II) are obtained by mixing aqueous solutions of Na[N(CN)2] and the respective alkali fluoride followed by slow H2O evaporation.

A series of robust and porous bipyridyl- and phenanthryl-based metal—organic frameworks (MOFs) of UiO topology is prepared and metalated with [Ir(cod)(OMe)]2 to provide Ir—MOF complexes which are highly active catalysts for tandem hydrosilylation of aryl ketones and aldehydes followed by dehydrogenative ortho-silylation as well as C—H boration of arenes.

The catalytic nature of self-assembled metal-organic polyhedra gives an entirely new dimension to the reactivity and properties of molecules within a well-defined confined space. Encapsulation of a range of guests brings about not only host-guest interactions but also gives rise to unusual reactivities with selectivity and stabilization of various reactive intermediates. This review briefly covers the synthesis of self-assembled metal-organic polyhedra and elaborates their influence in different chemical reactions as well as in the stabilization of unstable chemical species.

For benzoylthiourea substrates (I), bearing an electron-donating group at the para-position of the aryl group, the formation of benzamide (II) is favored.

Catalytic amounts of Co(SaltBu,tBu)Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.

Pincer-based catalysts possess an exceptional balance of stability versus reactivity, aspects of fundamental interest in catalyst design. This balance has been well-controlled by systematic ligand modifications along with the variation of the metal center. Ruthenium pincer complexes (RPCs), exhibit a versatile chemistry, serve as excellent precursors and find potential applications in many organic transformations. A large number of novel and valuable reactions has been developed using both stoichiometric and catalytic amounts of RPCs. Compared to the traditional ruthenium catalysts, pincer complexes often present high efficiency, selectivity and functional group tolerance. This review highlights different methodologies for the synthesis of RPCs and their catalytic applications for different reactions reported in the last decade. Additionally, the factors affecting the catalytic reactivity of the RPCs and the reaction mechanisms are discussed.

An efficient one-pot synthesis of isoindolin-1-ones is described starting from 2-iodobenzoic acid and arylalkynylcarboxylic acid or 2-propinoic acid in the presence of ammonium acetate [cf.

Carbohydrate–protein binding is a supramolecular recognition process that underpins myriad biological events. However, the precise conformational and configurational requirements for biomolecular recognition are often poorly understood, since such phenomena often occur in a strongly spatiotemporal manner. Photoswitchable glycoconjugates have emerged as promising investigational tools for probing carbohydrate–protein recognition and for controlling bacterial adhesion. Reversible photoisomerisation, in particular that of azobenzene glycoconjugates, has also been exploited as a promising strategy for controlling supramolecular self-assembly and macroscopic properties, thereby facilitating the development of light responsive carbohydrate-based materials. The following review will highlight the recent advances in the design and applications of photoswitchable glycoconjugates, paying particular attention to the application of light as a stimulus for modulating protein and cellular adhesion, amphiphilicity and supramolecular assembly of carbohydrate-based materials.

New well-designed materials are highly demanded with the prospect of versatile properties, offering successful applications as alternates to conventional materials. Major new insights into metal–organic self-assembled structures assisting biochemical purposes have recently emerged. Metal–organic polyhedral cages are highlighted as new research materials to be used for therapeutic, sensing and imaging, purposes etc. This tutorial review covers achievements in the biochemical applications of these multinuclear complexes. Examples of their ability to aid the ionic transport, biomolecular sensing, imaging, and drug delivery are presented.

Review: design of photoelectrochemical cells that combine water oxidation and CO2 reduction; 50 refs.

Metastable CuNbN2 is synthesized by a solid state ion-exchange reaction between polycrystalline NaNbN2 (obtained by solid state reaction of Na metal and NbN under ammonia flow at 500 °C for 24 h) and a 5-fold excess of CuI (N2 atmosphere, 300 °C, 48 h).

Direct preparation of tertiary amines in which two substituents are aromatic is described. In the presence of either the inorganic base sodium tert -butoxide or the sterically hindered organic base diisopropylethylamine, the alkylation of secondary diarylamines is achieved smoothly. In contrast to methods previously reported in the literature, this procedure is high-yielding and does not require the use of transition-metal catalysts or functional-group-intolerant hydride reductants.

The Dawson-type arsenato-phosphato tungstates of title are investigated by 183W and 31P NMR spectroscopy.

Mechanistic experiments suggest that the sequestration of free tris(pentafluorophenyl)borane by the hemilabile carboxylate contributes to the selectivity observed and prevents over reduction to methane.

The Fischer-Tropsch (FT) process, in which synthesis gas (syngas) derived from coal, natural gas, and biomass is converted into synthetic liquid fuels and chemicals, is a strongly exothermic reaction, and thus, a large amount of heat is generated during the reaction that could severely modify the overall selectivity of the process. In this Review, we report the advantages that can be offered by different thermally conductive supports, that is, carbon nanomaterials and silicon carbide, pure or doped with different promoters, for the development of more active and selective FT catalysts. This Review follows a discussion regarding the clear trend in the advantages and drawbacks of these systems in terms of energy efficiency and catalytic performance for this most-demanded catalytic process. It is demonstrated that the use of a support with an appropriate pore size and thermal conductivity is an effective strategy to tune and improve the activity of the catalyst and to improve product selectivity in the FT process. The active phase and the recovery of the support, which also represents a main concern in terms of the large amount of FT catalyst used and the cost of the active cobalt phase, is also discussed within the framework of this Review. It is expected that a thermally conductive support such as β-SiC will not only improve the development of the FT process, but that it will also be part of a new support for different catalytic processes for which high catalytic performance and selectivity are strongly needed.

Transparent, colorless crystals of the title compound are prepared by reaction of Yb2O3 and B powder in a KCl flux (Nb ampule, 1000 °C, 24 h).

YB2C2 and GdB2C2 are prepared from the elements by arc melting and subsequent annealing at 900 °C (3 d) and characterized by single crystal XRD.