Showing papers in "Dalton Transactions in 2010"
TL;DR: The status of platinum anticancer drugs currently approved for use, those undergoing clinical trials and those discontinued during clinical trials are updated, and the results in the context of where the field will develop over the next decade are discussed.
Abstract: Since its approval in 1979 cisplatin has become an important component in chemotherapy regimes for the treatment of ovarian, testicular, lung and bladder cancers, as well as lymphomas, myelomas and melanoma. Unfortunately its continued use is greatly limited by severe dose limiting side effects and intrinsic or acquired drug resistance. Over the last 30 years, 23 other platinum-based drugs have entered clinical trials with only two (carboplatin and oxaliplatin) of these gaining international marketing approval, and another three (nedaplatin, lobaplatin and heptaplatin) gaining approval in individual nations. During this time there have been more failures than successes with the development of 14 drugs being halted during clinical trials. Currently there are four drugs in the various phases of clinical trial (satraplatin, picoplatin, Lipoplatin™ and ProLindac™). No new small molecule platinum drug has entered clinical trials since 1999 which is representative of a shift in focus away from drug design and towards drug delivery in the last decade. In this perspective article we update the status of platinum anticancer drugs currently approved for use, those undergoing clinical trials and those discontinued during clinical trials, and discuss the results in the context of where we believe the field will develop over the next decade.
1,401 citations
TL;DR: Neutral or cationic arene ruthenium complexes providing both hydrophilic as well as hydrophobic properties due to the robustness of the rUThenium-arene unit hold a high potential for the development of metal-based anticancer drugs.
Abstract: Neutral or cationic arene ruthenium complexes providing both hydrophilic as well as hydrophobic properties due to the robustness of the ruthenium–arene unit hold a high potential for the development of metal-based anticancer drugs. Mononuclear arene ruthenium complexes containing P- or N-donor ligands or N,N-, N,O- or O,O-chelating ligands, dinuclear arene ruthenium systems with adjustable organic linkers, trinuclear arene ruthenium clusters containing an oxo cap, tetranuclear arene ruthenium porphyrin derivatives that are photoactive, as well as hexanuclear ruthenium cages that are either empty or filled with other molecules have been shown to be active against a variety of cancer cells.
554 citations
TL;DR: The obviously increased performance of g-C(3)N(4)-TaON is ascribed mainly to enhancement of electron-hole separations both at the interface and in the semiconductors.
Abstract: Organic–inorganic composite photocatalyst g-C3N4–TaON with visible-light response was prepared by a milling-heat treatment method. The photocatalyst was characterized by X-ray diffraction, high-resolution transmission electron microscopy and UV-vis diffuse reflection spectroscopy. The activity of composite photocatalyst g-C3N4–TaON for photodegradation of rhodamine B is higher than that of either single-phase g-C3N4 or TaON. The obviously increased performance of g-C3N4–TaON is ascribed mainly to enhancement of electron–hole separations both at the interface and in the semiconductors.
538 citations
TL;DR: This article focuses on recent developments in important new reactions and new catalysts for homogeneous CO(2) transformations under mild reaction conditions.
Abstract: The use of carbon dioxide as a renewable and environmentally friendly source of carbon is highly attractive. This article focuses on recent developments in important new reactions and new catalysts for homogeneous CO2 transformations under mild reaction conditions. Other than traditional organometallic catalysts, organocatalysts have also been applied in the chemical conversion of CO2 and have demonstrated very promising ability in this field. As the coupling of epoxides with CO2 to form cyclic carbonates or polycarbonates has been well documented, it will be excluded from this article.
511 citations
TL;DR: This Perspective article summarizes efforts paid in this group to develop efficient metal-based catalysts for the immortal ring-opening polymerization (iROP) of cyclic esters in the presence of large amounts of alcohols (ROH) as chain transfer agents.
Abstract: This Perspective article summarizes efforts paid in our group to develop efficient metal-based catalysts for the immortal ring-opening polymerization (iROP) of cyclic esters in the presence of large amounts of alcohols (ROH) as chain transfer agents. The catalyst systems reviewed include discrete organometallic complexes based on rare earths, magnesium, calcium and more specifically zinc, as well as simple systems employing metal triflate salts, notably Al(OTf)3, for the (stereo)controlled iROP of lactide (LA), β-butyrolactone (BBL) and trimethylenecarbonate (TMC). Special emphasis is given to systems that allow the use of minute amounts of metal catalysts and large loadings of both monomer and alcohol for the rapid and productive formation of functional polyesters (H–Pol–OR) with controlled molecular features.
430 citations
TL;DR: The theoretical framework for designing molecular nanomagnets for enhanced cooling requires the control and optimization of the quantum properties at the molecular level, in particular: spin ground state, magnetic anisotropy, and presence of low-lying excited spin states.
Abstract: Molecular nanomagnets are considered valid candidates for magnetic refrigeration at low temperatures. Designing these materials for enhanced cooling requires the control and optimization of the quantum properties at the molecular level, in particular: spin ground state, magnetic anisotropy, and presence of low-lying excited spin states. Herein, we present the theoretical framework together with a critical review of recent results, and perspectives for future developments.
399 citations
TL;DR: The areas in which the copper(I) catalyzed azide-alkyne cycloaddition has been applied to the synthesis of novel triazole-containing ligands for transition metals are summarized.
Abstract: The copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) is the premier example of a click reaction. The reaction is modular, reliable and easy to perform, providing easy access to molecular diversity. The majority of reported applications of the reaction employ the 1,2,3-triazole as a stable linkage to connect two chemical/biological components, while the potential for metal coordination of the heterocycle itself has received much less attention. In fact, 1,4-functionalized 1,2,3-triazoles are versatile ligands offering several donor sites for metal coordination, including N3, N2 and C5. In this article, we summarize the areas in which the CuAAC has been applied to the synthesis of novel triazole-containing ligands for transition metals.
339 citations
TL;DR: A recent DFT study by Houk, Buchwald and co-workers shows that the modified Ullmann reaction between aryl iodide and amines or primary alcohols proceeds either via an SET or an IAT mechanism, suggesting a Cu(I)/Cu(III) type mechanism for the amidation (Goldberg) reaction.
Abstract: The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of these modified Ullmann reactions. Most authors agree that Cu(I) is the true catalyst even though Cu(0) and Cu(II) catalysts have also shown to be active. It should be noted however that Cu(I) is capable of reversible disproportionation into Cu(0) and Cu(II). In the first step, the nucleophile displaces the halide in the LnCu(I)X complex forming LnCu(I)ZR (Z = O, NR′, S). Quite a number of mechanisms have been proposed for the actual reaction of this complex with the aryl halide: 1. Oxidative addition of ArX forming a Cu(III) intermediate followed by reductive elimination; 2. Sigma bond metathesis; in this mechanism copper remains in the Cu(II) oxidation state; 3. Single electron transfer (SET) in which a radical anion of the aryl halide is formed (Cu(I)/Cu(II)); 4. Iodine atom transfer (IAT) to give the aryl radical (Cu(I)/Cu(II)); 5. π-complexation of the aryl halide with the Cu(I) complex, which is thought to enable the nucleophilic substitution reaction. Initially, the radical type mechanisms 3 and 4 where discounted based on the fact that radical clock-type experiments with ortho-allyl aryl halides failed to give the cyclised products. However, a recent DFT study by Houk, Buchwald and co-workers shows that the modified Ullmann reaction between aryl iodide and amines or primary alcohols proceeds either via an SET or an IAT mechanism. Van Koten has shown that stalled aminations can be rejuvenated by the addition of Cu(0), which serves to reduce the formed Cu(II) to Cu(I); this also corroborates a Cu(I)/Cu(II) mechanism. Thus the use of radical clock type experiments in these metal catalysed reactions is not reliable. DFT calculations from Hartwig seem to confirm a Cu(I)/Cu(III) type mechanism for the amidation (Goldberg) reaction, although not all possible mechanisms were calculated.
312 citations
TL;DR: The present perspective provides a review of the many studies concerned with the synthesis, crystal structure and thermoelectric properties of clathrates with emphasis on the type I clathrate.
Abstract: Thermoelectric clathrates hold significant promise for high temperature applications with zT values exceeding 1.3. The inorganic clathrates have been shown to be both chemically and thermally stable at high temperatures, and high performance can be obtained from both single crystals and processed powders. The clathrates also show excellent compatibility factors in segmented module applications. For a materials chemist it is furthermore of great importance that the clathrates exhibit a very rich chemistry with the ability for substitution of many different elements. This allows delicate tuning of both the crystal structure as well as the physical properties. With all these assets, it is not surprising that clathrates have been intensely investigated in the thermoelectric community during the past decade. The present perspective provides a review of the many studies concerned with the synthesis, crystal structure and thermoelectric properties of clathrates with emphasis on the type I clathrate.
272 citations
TL;DR: In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed and general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic liquid and reaction conditions.
Abstract: In a supported ionic liquid phase (SILP) catalyst system, an ionic liquid (IL) film is immobilized on a high-surface area porous solid and a homogeneous catalyst is dissolved in this supported IL layer, thereby combining the attractive features of homogeneous catalysts with the benefits of heterogeneous catalysts. In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed. In the first part, general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic liquid and reaction conditions. Secondly, organic reactions in which SILP technology is applied to improve the performance of homogeneous transition-metal catalysts are presented: hydroformylation, metathesis reactions, carbonylation, hydrogenation, hydroamination, coupling reactions and asymmetric reactions.
225 citations
TL;DR: The magnetic properties of selected nanosized polyoxometalate clusters featuring spin triangles as their magnetic 'building blocks' or fragments are discussed, which allow the study of the implications of frustrated spin ordering.
Abstract: The structural versatility characterizing polyoxometalate chemistry, in combination with the option to deliberately use well-defined building blocks, serves as the foundation for the generation of a large family of magnetic clusters, frequently comprising highly symmetric spin arrays. If the spin centers are coupled by antiferromagnetic exchange, some of these systems exhibit spin frustration, which can result in novel magnetic properties of purely molecular origins. We discuss here the magnetic properties of selected nanosized polyoxometalate clusters featuring spin triangles as their magnetic ‘building blocks’ or fragments. This includes unique porous Keplerate clusters of the type {(Mo)Mo5}12M30 (M = FeIII, CrIII, VIV) with the spin centers defining a regular icosidodecahedron and the {V15As6}-type cluster sphere containing a single equilateral spin triangle; these species are widely discussed and studied in the literature for their role in materials science as molecular representations of Kagome lattices and in relation to quantum computing, respectively. Exhibiting fascinating and unique structural features, these magnetic molecules allow the study of the implications of frustrated spin ordering. Furthermore, this perspective covers the impact of spin frustration on the degeneracy of the ground state and related problems, namely strong magnetic anisotropy and the interplay of antisymmetric exchange and structural Jahn–Teller effects.
TL;DR: This perspective summarizes the chemistry of boroxines and outlines progress towards incorporating these ring structures into functional materials and macromolecular architectures.
Abstract: This perspective summarizes the chemistry of boroxines and outlines progress towards incorporating these ring structures into functional materials and macromolecular architectures. Special attention is paid to the dynamic covalent chemistry of boroxine ring construction and how these processes lead to novel molecular architectures and functional materials. Also highlighted in this perspective is the rich chemistry surrounding boroxine–ligand interactions and how these interactions flavor many areas of boroxine chemistry.
TL;DR: The metal-organic complexes of Sc, Y, La and lanthanides, which were tested as luminescent materials in organic light emitting diodes (OLEDs), are collected and advantages and drawbacks of organic derivatives of rare earth metals as emissive materials are considered.
Abstract: The metal–organic complexes of Sc, Y, La and lanthanides, which were tested as luminescent materials in organic light emitting diodes (OLEDs), are collected. The performances of the devices are given. Advantages and drawbacks of organic derivatives of rare earth metals as emissive materials are considered.
TL;DR: The experimental data suggest that mefenamic acid acts as deprotonated monodentate ligand coordinated to Co(II) ion through a carboxylato oxygen as well as showing good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.
Abstract: Cobalt(II) complexes with the non-steroidal anti-inflammatory drug mefenamic acid in the presence or absence of nitrogen donor heterocyclic ligands (2,2′-bipyridine, 1,10-phenanthroline or pyridine) have been synthesized and characterized with physicochemical and spectroscopic techniques. The experimental data suggest that mefenamic acid acts as deprotonated monodentate ligand coordinated to Co(II) ion through a carboxylato oxygen. The crystal structures of tetrakis(methanol)bis(mefenamato)cobalt(II), 1 and (2,2′-bipyridine)bis(methanol)bis(mefenamato)cobalt(II), 2 have been determined by X-ray crystallography. The EPR spectra of complexes 1 and 2 in frozen solution reveal that they retain their structures. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA and bis(methanol)bis(pyridine)bis(mefenamato)cobalt(II) exhibits the highest binding constant. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The cyclic voltammograms of the complexes recorded in dmso solution and in the presence of CT DNA in 1 : 2 dmso : buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that they can bind to CT DNA by the intercalative binding mode. Mefenamic acid and its cobalt(II) complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values. The antioxidant activity of the compounds has been evaluated indicating their high scavenging activity against hydroxyl free radicals and superoxide radicals.
TL;DR: This Perspective compares and contrasts the binding modes, reduction levels, and electronic influences on the nature of the bound O( 2) or N(2) group in these complexes.
Abstract: Transition-metal complexes of O2 and N2 play an important role in the environment, chemical industry, and metalloenzymes. This Perspective compares and contrasts the binding modes, reduction levels, and electronic influences on the nature of the bound O2 or N2 group in these complexes. The charge distribution between the metal and the diatomic ligand is variable, and different models for describing the adducts have evolved. In some cases, single resonance structures (e.g. M–superoxide = M–O2−) are accurate descriptions of the adducts. Recent studies have shown that the magnetic coupling in certain N22− complexes differs between resonance forms, and can be used to distinguish experimentally between resonance structures. On the other hand, many O2 and N2 complexes cannot be described well with a simple valence-bond model. Defining the situations where ambiguities occur is a fertile area for continued study.
TL;DR: The cellular accumulation of metal complexes is reviewed, including their uptake, localization, and efflux, as well as methods used to examine cellular accumulation, to identify the mechanism(s) of uptake, and to monitor possible efflux.
Abstract: Transition metal complexes offer great potential as diagnostic and therapeutic agents, and a growing number of biological applications have been explored. To be effective, these complexes must reach their intended target inside the cell. Here we review the cellular accumulation of metal complexes, including their uptake, localization, and efflux. Metal complexes are taken up inside cells through various mechanisms, including passive diffusion and entry through organic and metal transporters. Emphasis is placed on the methods used to examine cellular accumulation, to identify the mechanism(s) of uptake, and to monitor possible efflux. Conjugation strategies that have been employed to improve the cellular uptake characteristics of metal complexes are also described.
TL;DR: Particular attention is focused on the recent developments in this area, such as the synthesis of the bis(imido) analogues of the uranyl ion, and the isolation of the first mu-nitrido complexes of this element.
Abstract: There is a growing interest in uranium coordination chemistry, particularly as it relates to metal–ligand multiple bonding, and in the last decade significant progress has been made in synthesizing oxo, imido, μ-nitrido, and carbene-containing complexes of uranium. This review summarizes the synthesis, structure and reactivity of these complexes, starting from the inception of the field in 1981. Particular attention is focused on the recent developments in this area, such as the synthesis of the bis(imido) analogues of the uranyl ion, and the isolation of the first μ-nitrido complexes of this element.
TL;DR: The molar ratios of NH(4)F to TiO(2) (R) exhibit a significant influence on the morphology and photocatalytic activity of the TiO (2) samples and a possible formation mechanism by localized Ostwald ripening or chemically induced self-transformation is proposed based on the experimental observations.
Abstract: Mesporous anatase-phase TiO2 hollow spheres with high photocatalytic activity were prepared by hydrothermal treatment and self-transformation of amorphous TiO2 solid spheres in an NH4F aqueous solution. The prepared samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms and UV-vis absorption spectroscopy. The photocatalytic activity was evaluated by photocatalytic oxidation decomposition of acetone in air under UV irradiation. It is found that F− plays an essential role in the formation of TiO2 hollow spheres. F− not only induces the hollowing of TiO2 solid spheres, but also promotes the crystallization of anatase TiO2 nanocrystals. A possible formation mechanism for the TiO2 hollow spheres by localized Ostwald ripening or chemically induced self-transformation is proposed based on the experimental observations. Furthermore, the molar ratios of NH4F to TiO2 (R) exhibit a significant influence on the morphology and photocatalytic activity of the TiO2 samples. The photocatalytic activity of the samples prepared in the presence of NH4F is higher than that of TiO2 sample prepared in pure water and commercial Degussa P25 (P25) powders. Especially, the TiO2 hollow spheres prepared at R = 1 show the highest photocatalytic activity and the specific rate constant Sk exceeds that of P25 by a factor of more than two.
TL;DR: This Perspective reviews recent advances in f-element hydroelementation for highly selective hydroalkoxylation and hydrothiolation processes and compares/contrasts analogous C-N and C-P bond-forming transformations.
Abstract: Lanthanide and actinide catalysts have made significant contributions to many areas of homogeneous catalysis with hydroelementation of C–C unsaturation being a notable area of success. In this Perspective, we review recent advances in f-element hydroelementation for highly selective hydroalkoxylation and hydrothiolation processes. As will be discussed, f-element hydroalkoxylation and hydrothiolation catalysts exhibit selectivities unobtainable by many late transition metal complexes. First, we review lanthanide-mediated hydroalkoxylation processes with mechanistic, thermodynamic, and kinetic considerations discussed, and then compare/contrast them with analogous C–N and C–P bond-forming transformations. In addition, computational studies are discussed which provide further insight into this transformation and the observed selectivities. Next, actinide-mediated alkyne hydrothiolation is reviewed with a similar discussion of reactivity, mechanism, and thermodynamics.
TL;DR: The screening of well-defined systems in the hydrosilylation reaction allowed for the identification of a pre-catalyst previously overlooked since, originally, catalytic species were in situ generated, highlighting one of the most important advantages of employing well- defined complexes in catalysis.
Abstract: The preparation of three series of [(NHC)CuX] complexes (NHC = N-heterocyclic carbene, X = Cl, Br, or I) is reported. These syntheses are high yielding and only use readily available starting materials. The prepared complexes were spectroscopically and structurally characterized. Notably, two of them present a bridging NHC ligand between two copper centers in the solid state, an extremely rare coordination mode for these ligands. These complexes were then applied to two distinct organic reactions: the hydrosilylation of ketones and the 1,3-dipolar cycloaddition of azides and alkynes. In both transformations, outstanding catalytic systems were found for preparing the corresponding products in excellent yields and short reaction times. Most remarkably, the screening of well-defined systems in the hydrosilylation reaction allowed for the identification of a pre-catalyst previously overlooked since, originally, catalytic species were in situ generated. Under such conditions, major formation of [(NHC)2Cu]+ species, inactive in this reduction reaction, occurred instead of the expected copper hydride. These results highlight one of the most important advantages of employing well-defined complexes in catalysis: gaining an improved control of the nature of the catalytically relevant species in the reaction media.
TL;DR: This Perspective provides an overview of transition metal-catalyzed cross coupling reactions of polyfluoroarenes and stoichiometric C-F activation and subsequent reaction are briefly covered.
Abstract: This Perspective provides an overview of transition metal-catalyzed cross coupling reactions of polyfluoroarenes. When appropriate, stoichiometric C–F activation and subsequent reaction are briefly covered.
TL;DR: Herein, the efficient three-step synthesis of a novel highly hindered, but flexible, N-heterocyclic carbene and its coordination chemistry to Ag(i) and Rh(i).
Abstract: Herein, we wish to describe the efficient three-step synthesis of a novel highly hindered, but flexible, N-heterocyclic carbene and its coordination chemistry to Ag(I) and Rh(I).
TL;DR: High temperature transport measurements have previously been conducted for all known compositions except for SrZn(2)Sb(2); here this class is characterized to 723 K and the transport behavior of the other compounds in thisclass is reviewed.
Abstract: The AZn2Sb2 (Pm1, A = Ca, Sr, Eu, Yb) class of Zintl compounds has shown high thermoelectric efficiency (zT∼ 1) and is an appealing system for the development of Zintl structure–property relationships. High temperature transport measurements have previously been conducted for all known compositions except for SrZn2Sb2; here we characterize polycrystalline SrZn2Sb2 to 723 K and review the transport behavior of the other compounds in this class. Consistent with the known AZn2Sb2 compounds, SrZn2Sb2 is found to be a hole-doped semiconductor with a thermal band gap ∼ 0.27 eV. The Seebeck coefficients of the AZn2Sb2 compounds are found to be described by similar effective mass (m* ∼ 0.6 me). Electronic structure calculations reveal similar m* is due to antimony p states at the valence band edge which are largely unaffected by the choice of A-site species. However, the choice of A-site element has a dramatic effect on the hole mobility, with the room temperature mobility of the rare earth-based compositions approximately double that found for Ca and Sr on the A site. This difference in mobility is examined in the context of electronic structure calculations.
TL;DR: High quality MOF-177 crystals in the size range of 5-20 microm were successfully synthesized via a sonochemical route in a substantially reduced synthesis time in the presence of low-cost NMP (1-methyl-2-pyrrolidone) as a solvent.
Abstract: High quality MOF-177 crystals in the size range of 5–20 μm were successfully synthesized via a sonochemical route in a substantially reduced synthesis time (40 min) in the presence of low-cost NMP (1-methyl-2-pyrrolidone) as a solvent. Microwave heating in NMP also produced MOF-177 under similar conditions (35 min, 5–50 μm) but exhibited inferior crystallinity. In comparison, a conventional solvothermal route in DEF (diethylformamide) took 48 h to produce MOF-177 crystals 0.5–1.5 mm in size. The BET surface areas of the MOF-177 samples decreased in the order of sonochemical (4898 m2 g−1) > conventional (4833 m2 g−1) > microwave route (4197 m2 g−1). In line with this trend, MOF-177 prepared via the sonochemical route resulted in the highest CO2 adsorption capacity, 1315 mg g−1 at 30 bar and 298 K. The product yield of MOF-177 synthesized via the sonochemical route was 95.6%, and was significantly higher than the product yields of other methods.
TL;DR: This perspective provides a concise overview of known silylium ions, followed by examples of their uses as catalysts in C-F bond activation and C-C bond formation, namely challenging Diels-Alder reactions.
Abstract: The controversy over “how free the trivalent silicon cation is” placed the emphasis on their spectroscopic and crystallographic characterisation. Those investigations contributed substantially to the understanding of the role of σ or π Lewis basic molecules in the chemistry of extremely potent Lewis acids, culminating in the discovery of innocent, that is non-coordinating, anions and an X-ray molecular structure. Synthetic uses of such reactive intermediates are however underrepresented yet a few recent contributions offer a glimpse of their true potential. This perspective provides a concise overview of known silylium ions, followed by examples of their uses as catalysts in C–F bond activation and C–C bond formation, namely challenging Diels–Alder reactions.
TL;DR: The in vogue N-heterocyclic carbenes have attracted attention largely for its new found popularity in chemical catalysis and also for displaying promising traits in biomedical applications, and the current perspective provides an account of the efforts in exploring the utility of N/O-functionalized N- heterocyclo-carbenes in these two areas.
Abstract: The in vogue N-heterocyclic carbenes (NHCs) have attracted attention largely for its new found popularity in chemical catalysis and also for displaying promising traits in biomedical applications. The current perspective provides an account of our efforts in exploring the utility of N/O-functionalized N-heterocyclic carbenes in these two areas. On the catalysis front, we have employed the N/O-functionalized N-heterocyclic carbene based precatalysts for the C–C and C–N bond forming reactions like the Suzuki–Miyaura, Sonogashira and Hiyama cross-couplings, the base-free Michael addition, the alkene and alkyne hydroamination reactions and the ring-opening polymerization (ROP) of L-lactides that produce biodegradable polylactide polymers while on the biomedical application front, the anticancer and antimicrobial properties of these N/O-functionalized N-heterocyclic carbene complexes were evaluated. Towards this objective, the N-heterocyclic carbene chemistry of a variety of transition metals like Ag, Au, Ni and Pd has been investigated.
TL;DR: Barrios-Landeros et al. as mentioned in this paper used dispersion-corrected DFT (DFT-D) together with solvation to examine possible mechanisms for reaction of PhX (X = Cl, Br, I) with Pd(PtBu3)2 and compare their results to recently published kinetic data.
Abstract: We have used dispersion-corrected DFT (DFT-D) together with solvation to examine possible mechanisms for reaction of PhX (X = Cl, Br, I) with Pd(PtBu3)2 and compare our results to recently published kinetic data (F. Barrios-Landeros, B. P. Carrow and J. F. Hartwig, J. Am. Chem. Soc., 2009, 131, 8141–8154).1 The calculated activation free energies agree near-quantitatively with experimentally observed rate constants.
TL;DR: It is found, using HR-ESMS, (1)H NMR, and X-ray crystallography, that both discrete and polymeric metallosupramolecular architectures can be formed.
Abstract: A one pot, multicomponent CuAAC reaction has been exploited for the safe generation of alkyl, benzyl or aryl linked polydentate pyridyl-1,2,3-triazole ligands from their corresponding halides, sodium azide and alkynes in excellent yields. The ligands have been fully characterised by elemental analysis, HR-ESMS, IR, 1H and 13C NMR and in two cases the structures were confirmed by X-ray crystallography. Additionally, we have examined the Ag(I) coordination chemistry of these ligands and found, using HR-ESMS, 1H NMR, and X-ray crystallography, that both discrete and polymeric metallosupramolecular architectures can be formed.
TL;DR: Three-dimensional (3D) flower-like BiOI hierarchical structures have been successfully synthesized by a solution route at room temperature by proposing that primary nanoflakes of Bi-EtOH complexes were initially formed in the solution, and then anisotropic growth led to the development of 3D flowerlike structures.
Abstract: Three-dimensional (3D) flower-like BiOI hierarchical structures have been successfully synthesized by a solution route at room temperature. The obtained sample was systematically studied by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It is noteworthy that no surfactant or assisted reagent was needed during the formation of this uniform flower-like structure. It was proposed that primary nanoflakes of Bi-EtOH complexes were initially formed in the solution, and then anisotropic growth led to the development of 3D flowerlike structures. In addition, the photocatalytic property of the sample under visible-light was investigated with three types of dye: heteropolyaromatic (Methylene Blue (MB)), azoic (Methyl Orange (MO)) and phenol (rhodamine B (RhB)). High photocatalytic activity was observed for the phenol dye RhB. The electrochemical hydrogen storage properties were also investigated.
TL;DR: A facile hydrothermal route for controllable synthesis of novel Bi(2)WO(6) hierarchical hollow spheres with an ultrahigh specific surface area with superior photocatalytic activity in the photodegradation of rhodamine B (RhB) under visible light irradiation over other morphological products is demonstrated.
Abstract: Bismuth tungstate has attracted great attention as a new photocatalyst working under visible irradiation. In this paper, we demonstrate a facile hydrothermal route for controllable synthesis of novel Bi(2)WO(6) hierarchical hollow spheres with an ultrahigh specific surface area in the presence of poly(vinyl pyrrolidone) at a proper C(2)H(5)OH/CH(3)COOH/H(2)O volume ratio. The obtained products are systematically studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) and UV-vis absorption spectroscopy. It is shown that the Bi(2)WO(6) hollow spheres are constructed of numerous nanoplates while the nanoplates consist of a great deal of nanoparticles. UV-vis spectrum is used to estimate the band gap energy (about 2.90 eV) of the Bi(2)WO(6) hollow spheres. The ultrahigh BET specific surface area of ca. 45.0 m(2) g(-1) is displayed for the Bi(2)WO(6) hierarchical hollow spheres, which is much higher than that for all the previously reported Bi(2)WO(6) products. The Bi(2)WO(6) hierarchical hollow spheres are displayed to possess superior photocatalytic activity in the photodegradation of rhodamine B (RhB) under visible light irradiation over other morphological products.