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The example of alkylation of commercial zinc and cadmium powders with organic halides in the presence of binary systems comprising an organometallic and a transition metal compounds was used to show that the nature of the transition metal compound in the binary system strongly affects the rate of a steady-state process. Therewith, the significant factors are both the nature of the transition metal and the ligand composition. It was found that the activity of the binary systems correlates with the activity of the transition metal compound in the transmetalation reaction with the organometallic component of the binary system (reduction of the transition metal compound). [ABSTRACT FROM AUTHOR]

The first organometallic BOPHY (BOPHY=bis(difluoroboron)-1,2-bis{(pyrrol-2-yl)methylene}hydrazine) containing two ferrocene substituents was prepared through a Knoevenagel condensation between tetramethyl substituted BOPHY and ferrocene carboxaldehyde. An unprecedentedly strong long-range (≈17.2 Å) metal-metal coupling in this new complex was investigated using electrochemical, spectroelectrochemical, and chemical oxidation methods. Electrochemical data is indicative of a 200 mV separation between the first and the second ferrocene-centered oxidation processes. Formation of the mixed-valence states and appearance and disappearance of two NIR bands were observed during stepwise oxidation of the first organometallic BOPHY. The electronic structure and the nature of the excited states in this new chromophore were studied by DFT and TDDFT calculations. [ABSTRACT FROM AUTHOR]

The author discusses his important scientific accomplishments and exciting findings as a researcher. Topics cited include a collaboration with University College of London's chemistry professor Ronald Nyholm for the study of the synthesis of gold-containing metal-metal-bonded organometallic complexes, research on the centrosymmetrical, rhombus-like structure of the molecular mixed-metal clusters containing palladium and findings on reversible carbon dioxide fixation.

Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H2 + D2, which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by ¹H NMR spectrometry. At low temperatures, this reaction requires a catalyst, but it proceeds without a catalyst at high temperature of a gentle flame. The second deuterium/hydrogen exchange reaction involves CH4 + D2 producing a series of isotopologues, methane-dx, x = 0-4, with product analysis by GC-MS and ¹H NMR spectrometry. This reaction only takes place in the presence of a catalyst at elevated temperatures due to the large energy of activation of the sp³-carbon-to-hydrogen bond. Two outcomes have been observed in the literature regarding D/H exchange and methane. Some catalysts and temperature conditions yield a single-exchange result, methane-d1. Others yield multiple exchange results, such as we observe with our catalyst. The single exchange outcome is associated with lower temperatures. Two mechanisms, one by Kemball (1959) and one by Frennet (1974), have been put forth to explain single and multiple exchange outcomes. We discuss our results in the context of these mechanisms. Interested readers could develop a research experience for undergraduate chemistry students based on the open-ended experiments presented here. [ABSTRACT FROM AUTHOR]

An in-depth study of the metal-organic magnet Ni(TCNQ)2 was conducted where the deuterated form was synthesised both to attempt to alter the magnetic properties of the material and to be advantageous in techniques such as neutron scattering and muon spectroscopy. Deuteration saw a 3 K increase in TC with magnetization and heat capacity measurements demonstrating a spin wave contribution at low temperatures confirming the 3D nature of the ferromagnetic state shown by Ni(TCNQ-D4)2. AC susceptibility results suggest there is a glassy component associated with the magnetically ordered state, though muon spectroscopy measurements did not support the presence of a spin glass state. Instead muon spectroscopy at zero magnetic field indicated the presence of two magnetic transitions, one at 20 K and another below 6 K; the latter is likely due to the system entering a quasistatic regime, similar to what one might expect of a superspin or cluster glass. Neutron diffraction measurements further supported this by revealing very weak magnetic Bragg peaks suggesting that the magnetism may have a short coherence length and be confined to small grains or clusters. The separation of the ferromagnetic and glassy magnetic components of the material's properties suggest that this system may show promise as a metal-organic magnet which is easily modified to change its magnetic properties, providing larger grain sizes can be synthesized. [ABSTRACT FROM AUTHOR]

Five chiral metal-organic coordination compounds (CMOCCs), {[Cu4O(Lvcz)2Br4] ·H2O} n ( 1), {[Cd(HLvcz)2(NO3)2] ·0.25H2O} n ( 2), {[Cu2(HLvcz)2I2] ·H2O} n ( 3), {[Ag(HLvcz)2]CF3SO3} n ( 4), and {[Co2(HLvcz)(bdc)2(dmf)2] ·dmf ·3H2O} n ( 5; HLvcz = voriconazole, bdc = terephthalic acid), have been successfully prepared and structurally characterized. The chiral drug ligand voriconazole exhibits diverse modes of coordination in the five complexes, resulting in the formation of various architectures and properties. Complex 1 is a tetranuclear cluster, complex 2 exhibits a 1D double-strand chain structure in which hydrogen-bonding interactions lead to a 3D supramolecular network, complex 3 is a 1D chain structure with two different types of rings based on the rhombic dimer Cu2I2, complex 4 is a 2D structure with 63 topology that contains four types of C-H ···F hydrogen bonds, and complex 5 affords a 3D framework with sxa topology. Their properties, such as chirality, second-order nonlinear optical (NLO) effects, ferroelectric behavior and dielectric anomalies, have been investigated in the solid state. [ABSTRACT FROM AUTHOR]

Developing new green solvents in designing chemical products and processes or successfully employing the already existing ones is one of the key subjects in green chemistry and is especially important in organometallic chemistry, which is an interdisciplinary field. Can we advantageously also use unconventional reaction media in place of current harsh organic solvents for polar organometallic compounds? This microreview critically analyses the state of the art with regard to this topic and showcases recent developments and breakthroughs that are becoming new research directions in this field. Because metals cover a vast swath of the Periodic Table the content is organised into three sections discussing the reactivity of organometallic compounds of s-, p- and d-block elements in unconventional solvents. [ABSTRACT FROM AUTHOR]

Four new complexes based on 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) and four bis-pyridyl-bis-amide ligands with various spacers (3-bpye = N,N'-bis(3-pyridinecarboxamide)-1,2-ethane; 3-bpfp = bis(3-pyridylformyl)piperazine; 3-bpcd = N,N'-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide; and 3-bpcb = N,N'-bis(3-pyridinecarboxamide)-1,4-benzene), namely [Cu2(1,4-NDC)2(3-bpye)(H2O)] (1), [Cu(1,4-NDC)(3-bpfp)0.5(2), [Cu3(1,4-NDC)3(3-bpcd)3·2H2O (3), and [Cu(1,4-NDC)(3-bpcb) (4), have been hydrothermally synthesized. Complex 1 is a 3D coordination network and represents an 8-connected {420.68} topology. Complex 2 shows a 2-fold interpenetrating 3D architecture with a 6-connected {412.63} topology. Complexes 3 and 4 possess similar 2D sql layers with the {44.62} topology, but the coordination modes of 1,4-NDC ligands and the conformations of the two bis-pyridyl-bis-amide ligands are different. The adjacent layers for 3 and 4 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. The successful assemblies of complexes 1-4 imply that by using the different bis-pyridyl-bis-amide ligands with diverse spacers can produce diverse metal-organic networks. Furthermore, the fluorescence and photocatalytic properties of complexes 1-4 have been investigated. [ABSTRACT FROM AUTHOR]

The article offers world news briefs on chemistry research as of October 2015. A study by the researchers at Virginia Tech University found that organometallic complexes containing iridium can fight against methicillin-resistant staphylococcus aureus infection. Australian researchers have created a metallic glass manual that can predict the combinations of metals that will form metallic glass alloys. A process of three-dimensional printing for microsized robot fish was developed in the U.S.

Tri-methyl-indium (TMI) is used as an indium transport molecule to introduce indium atoms to reactive hot gas flows/combustion environments for spectroscopic diagnostics. A seeding system was constructed to allow the addition of an inert TMI laden carrier gas into an air/fuel mixture burning consequently on a burner. The amount of the seeded TMI in the carrier gas can be readily varied by controlling the vapor pressure through the temperature of the container. The seeding process was calibrated using the fluorescent emission intensity from the indium 6²S1/2 → 52P1/2 and 6²S1/2 → 5²P3/2 transitions as a function of the calculated TMI seeding concentration over a range of 2-45 ppm. The response was found to be linear over the range 3-22.5 ppm; at concentrations above 25 ppm there is a loss of linearity attributable to self-absorption or loss of saturation of TMI vapor pressure in the carrier gas flow. When TMI was introduced into a post-combustion environment via an inert carrier gas, molecular transition from InH and InOH radicals were observed in the flame emission spectrum. Combined laser-induced fluorescence and absorption spectroscopy were applied to detect indium atoms in the TMI seeded flame and the measured atomic indium concentration was found to be at the ppm level. This method of seeding organometallic vapor like TMI to a reactive gas flow demonstrates the feasibility for quantitative spectroscopic investigations that may be applicable in various fields, e.g., chemical vapor deposition applications or temperature measurement in flames with two-line atomic fluorescence. [ABSTRACT FROM AUTHOR]

The best-known application of salen complexes is the use of a chiral ligand loaded with manganese to form the Jacobsen complex. This organometallic catalyst is used in the epoxidation of unfunctionalized olefins and can achieve very high selectivities. Although this application was proposed many years ago, the mechanism of oxygen transfer remains a question until now. In this paper, the epoxidation mechanism is investigated by an ab initio kinetic modeling study. First of all a proper DFT functional is selected that yields the correct ordering of the various spin states. Our results show that the epoxidation proceeds via a radical intermediate. If we start from the radical intermediate, these results can explain the experiments with radical probes. The subtle influences in the transition state using the full Jacobsen catalyst explain the product distribution observed experimentally. [ABSTRACT FROM AUTHOR]

The article discusses a study on the use of fluorinated ligands in changing the properties of metal-organic precursors for material processing. Topics covered the different kinds of metal compounds such as metal alkoxides, carboxylates, and beta-diketonates, its benefits focusing on enhanced thermal and hydrolytic stability, better solubility, and improved mass-transport properties, and further research on heterometallic single source precursors and metal organic frameworks.

Water-soluble cyclodextrins (CDs) bearing two nitrogen atoms as metal coordinating sites have been synthesized. An appropriate phosphane could be included within their cavity through the primary face to form self-assembled PNN supramolecular edifices. Once the PNN ligands were coordinated to platinum, the resulting complexes proved to be very effective as catalysts in a domino reaction, where a Pt-catalyzed reduction of nitrobenzene was followed by a Paal–Knorr pyrrole reaction. In the nitrobenzene reduction, the modified CDs acted both as first- and second-sphere ligands. Contrary to an acyclic glucopyranose-based NN ligand unable to interact with a phosphane ligand, the CD-based PNN ligands stabilized the catalytic species in water by supramolecular means. Interestingly, the product and the water-soluble Pt-catalyst could be recovered in two different phases once the reaction was complete. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have proved to be very attractive for applications including gas storage, separation, sensing and catalysis. In particular, CO2 separation from flue gas in post-combustion processes is one of the main focuses of research among the scientific community. One of the major issues that are preventing the successful commercialization of these novel materials is their high affinity towards water that not only compromises gas sorption capacity but also the chemical stability. In this paper, we demonstrate a novel post-synthesis modification approach to modify MOFs towards increasing hydrophobic behaviour and chemical stability against moisture without compromising CO2 sorption capacity. Our approach consists of incorporating hydrophobic moieties on the external surface of the MOFs via physical adsorption. The rationale behind this concept is to increase the surface hydrophobicity in the porous materials without the need of introducing bulky functionalities inside the pore which compromises the sorption capacity toward other gases. We herein report preliminary results on routinely studied MOF materials [MIL-101(Cr) and NiDOBDC] demonstrating that the polymer-modified MOFs retain CO2 sorption capacity while reducing the water adsorption up to three times, with respect to the un-modified materials, via an equilibrium effect. Furthermore, the water stability of the polymer-functionalized MOFs is significantly higher than the water stability of the bare material. Molecular dynamic simulations demonstrated that this equilibrium effect implies a fundamental and permanent change in the water sorption capacity of MOFs. This approach can also be employed to render moisture stability and selectivity to MOFs that find applications in gas separations, catalysis and sensing where water plays a critical role in compromising MOF performance and recyclability. [ABSTRACT FROM AUTHOR]

The metal organic framework, MOF-74(Ni), was synthesized in a continuous flow microwave-assisted reactor obtaining a high space-time yield (~90 g h−1 L−1) and 96.5% conversion of reagents. Separation of the nucleation and growth steps was performed by using uniform and rapid microwave heating to induce nucleation, which allowed a substantial increase in conversion for shorter reaction times under mild pressure. High yields were achieved in minutes, as opposed to days for typical batch syntheses, with excellent control over the material's properties due to more uniform nucleation, and the separation of the nucleation and growth steps. Optimization of the microwave reactor parameters led to improvements in MOF-74(Ni) crystallinity, reagent conversion, and production rates. Differences in MOF-74(Ni) crystallinity were observed as smaller grains were formed when higher microwave zone temperatures were used. Crystallinity differences led to different final adsorption properties and surface areas. Herein we show that a continuous high space-time yield synthesis of MOF-74(Ni) allows control over nucleation using microwave heating. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks {[Ln4(pztc)3(H2O)11]·10(H2O)}n (Ln = Gd(1), Tb(2); pztc = pyrazine-2,3,5,6-tetracarboxylate) containing variable coordination spheres and with a complex and unusual three dimensional structure, were synthesized by the reaction of H4pztc with the respective Ln(iii) salt in water under hydrothermal conditions. The compounds were characterized by single crystal X-ray crystallography, elemental and thermal analysis, and FTIR spectroscopy. The asymmetric units in these compounds have four symmetry-independent Ln(iii) ions and these are octa- and nona-coordinate centers, with irregular coordination polyhedra from [Ln(pztc)2(H2O)6], [Ln(pztc)2(H2O)4], [Ln(pztc)3(H2O)3], [Ln(pztc)3(H2O)], and [Ln(pztc)4] cluster units. The fully deprotonated ligand, pztc, coordinates to the Ln3+ ions through seven or through ten of its atoms (i.e., the maximum coordination number for this ligand). The three-dimensional open framework contains irregular channels along the [001] crystallographic direction. The channels are approximately 12 Å wide at their largest dimension and contain strongly hydrogen bonded water molecules of crystallization which further stabilize the structure. The solvent accessible volume is 20% of the total volume. The structures exhibit magnetic behavior that is characteristic of the respective isolated paramagnetic lanthanide ions. [ABSTRACT FROM AUTHOR]

Quantum-chemical B3LYP/6-31G(d,p) method was applied to the investigation of the formation of 4,5-dihydro-3 H-azepine and/or 4,5-dihydro-1,3-thiazole structures from (propargylsulfanyl)-substituted 2-aza-1,3,5-triene at treatment with potassium tert-butoxide. According to the calculation the formation of 4,5-dihydro-1,3-thiazole ring prevailed. [ABSTRACT FROM AUTHOR]

Using alkylation of commercial zinc and cadmium powders with organic halides in the presence of the organometallic compound-copper(I) iodide binary systems as an example, it has been demonstrated that the rate of the stationary process can be drastically varied depending on the nature of the organometallic component. Both the nature of the metal and the ligand composition of the organometallic compound were significant factors. Activity of the binary systems in the considered process correlates with the organometallic component reactivity upon its transmetalation with the second compulsory component of the binary system (the transition metal compound). [ABSTRACT FROM AUTHOR]

A bulky, optically active monoanionicscorpionate ligand, tris(4S-isopropyl-5,5-dimethyl-2-oxazolinyl)phenylborate(ToP*), is synthesized from the naturally occurring aminoacid l-valine as its lithium salt, Li[ToP*] (1). That compound is readily converted to the thallium complexTl[ToP*] (2) and to the acid derivative H[ToP*] (3). Group 7 tricarbonyl complexes ToP*M(CO)3(M = Mn (4), Re (5))are synthesized by the reaction of MBr(CO)5and Li[ToP*] and are crystallographically characterized. The νCObands in their infrared spectra indicate that π back-donationin the rhenium compounds is greater with ToP* than withnon-methylated tris(4S-isopropyl-2-oxazolinyl)phenylborate(ToP). The reaction of H[ToP*] and ZnEt2gives ToP*ZnEt (6), while ToP*ZnCl (7) is synthesized from Li[ToP*] and ZnCl2. The reaction of ToP*ZnCl andKOtBu followed by addition of PhSiH3providesthe zinc hydride complex ToP*ZnH (8). Compound 8is the first example of a crystallographically characterizedoptically active zinc hydride. We tested its catalytic reactivityin the cross-dehydrocoupling of silanes and alcohols, which providedSi-chiral silanes with moderate enantioselectivity. [ABSTRACT FROM AUTHOR]

NH2-MIL-125, [Ti8O8(OH)4(bdc-NH2)6] (bdc2-=1,4- benzene dicarboxylate) is a highly porous metal-organic framework (MOF) that has a band gap lying within the ultraviolet region at about 2.6 eV. The band gap may be reduced by a suitable post-synthetic modification of the nanochannels using conventional organic chemistry methods. Here, it is shown that the photocatalytic activity of NH2-MIL-125 in the degradation of methylene blue under visible light is remarkably augmented by post-synthetic modification with acetylacetone followed by CrIII complexation. The latter metal ion extends the absorption from the ultraviolet to the visible light region (band gap 2.21 eV). The photogenerated holes migrate from the MOF's valence band to the CrIII valence band, promoting the separation of holes and electrons and increasing the recombination time. Moreover, it is shown that the MOF's photocatalytic activity is also much improved by doping with Ag nanoparticles, formed in situ by the reduction of Ag+ with the acetylacetonate pendant groups (the resulting MOF band gap is 2.09 eV). Presumably, the Ag nanoparticles are able to accept the MOF's photogenerated electrons, thus avoiding electron-hole recombination. Both, the Cr- and Ag-bearing materials are stable under photocatalytic conditions. These findings open new avenues for improving the photocatalytic activity of MOFs. [ABSTRACT FROM AUTHOR]

Bis( N-ethylbenzimidazol-2-ylmethyl)aniline (Etbba) and its transition metal complexes, [Cu(Etbba)(Cl)2]⋅DMF ( 1), [Mn(Etbba)(Cl)2] ( 2) and [Ni(Etbba)(Cl)2] ( 3), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, UV-visible, infrared and NMR spectroscopies and X-ray crystallography. The coordination environment of complex 1 can be described as distorted square-based pyramidal, while complexes 2 and 3 each have a distorted trigonal bipyramidal geometry. Cyclic voltammograms of complex 1 indicate an electrochemically quasi-reversible Cu2+/Cu+ couple. In addition, the antioxidant activities of the free ligand and its complexes were investigated using the superoxide and hydroxyl radical scavenging methods in vitro. Complexes 1, 2, 3 are found to possess potent hydroxyl radical scavenging activity and to be better than standard antioxidants like vitamin C and mannitol. Furthermore, complexes 1 and 2 exhibit significant superoxide radical activity. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The incorporation of sulfonate into mesoporous SBA-15 as ligands for palladium ions was used. Then SBA-15/PrSO3Pd and SBA-15/PrSO3PdNP were prepared and applied for the Heck reaction of conjugate alkenes with aryl halides, to afford corresponding products under phosphine-free aerobic conditions with good to excellent yields. These supported palladium pre-catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Novel Cu(II), Fe(III) and Mn(III) salen-type metal complexes from (1 R,3 S)- N, N′-bis[salicylidene]-1,3-diamino-1,2,2-trimethylcyclopentane were synthesized and screened for their in vitro cytotoxic activity against three human cancer cell lines: melanoma, colorectal and breast. In vitro experiments carried out with the three metal complexes show that the copper complex exhibits the highest cytotoxic activity towards all cell lines studied, presenting IC50 values of 3.32-6.71 μM. A significant improvement in the anti-proliferative effect, by 20-fold, is observed with this complex when compared with conventional chemotherapy. The relationship between structure, redox characteristics and in human cancer cell lines was evaluated for the most efficient Cu(II) complex and associated with theoretical calculations. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

New 1,3-dialkyltetrahydropyrimidinium salts as NHC precursors have been synthesized and characterized. The in situ prepared three-component 1,3-dialkyltetrahydropyrimidinium salts/[RuCl2( p-cymene)]2 and KOH catalyzes quantitatively the of ketones under mild reaction conditions in 2-propanol. Also, the molecular structure of 1,3-bis(2-methylbenzyl)-3,4,5,6-tetrahydropyrimidinium was determined using single-crystal X-ray diffraction. Ions of the title compound are linked by CH...Cl and OH...Cl hydrogen bonding interactions. The NCN bond angle (124.3(2)°) and CN bond lengths (1.316(3) and 1.314(3) Å) confirm the existence of strong resonance in this part of the molecule. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Cobalt(II), iron(III) or oxovanadium(II) Schiff base metal complexes have been covalently grafted onto graphene oxide ( GO) previously functionalized with 3-aminopropyltriethoxysilane. Potential catalytic behaviors were tested in the of styrene, using air as the oxidant. The catalysts were characterized using infrared (IR) and Raman spectroscopies, thermogravimetric analyses, atomic (ICP-AES), X-ray diffraction, nitrogen adsorption-desorption, scanning (SEM) and transmission (TEM). IR spectroscopy, thermogravimetric analyses and ICP-AES confirmed the successful incorporation of the metal Schiff base complexes onto GO. X-ray diffraction, nitrogen adsorption-desorption, , SEM and TEM showed the intact structure of the GO. Co-GO and Fe-GO showed high styrene conversion (90.8 versus 86.7%) and epoxide selectivity (63.7 versus 51.4%). Nevertheless, VO-GO showed poorer catalytic performance compared with Co-GO and Fe-GO. The recycling results of these heterogeneous catalysts showed good recoverability without significant loss of activity and selectivity within four successive runs. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Fe-Sn-O mixed oxides were synthesized and used as catalysts for of cyclohexanone, which showed both high and selectivity. X-ray and scanning suggested that the Fe-Sn-O catalysts had a tetragonal structure with a grain size of 29.3 nm. An ε-caprolactone yield as high as 98.8% was obtained in a small-scale experiment (5 mmol of cyclohexanone). In a scale-up test (20 mmol of cyclohexanone), the cyclohexanone conversion and ε-caprolactone yield were 96.7 and 96.5%, respectively. In addition, the catalysts can be reused five times without any major decline in . Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

By introducing different surfactants into a reaction system, two previous mixed-phase Ni(ii)–MOFs constructed from an undeveloped pyridyl-tetracarboxylate and Ni(ii) salts were successfully isolated to obtain two pure products. Compound 1 exhibits a 3D H-bonded network with (3,8)-connected {4.52}2{42.56.614.72.84} topology, while 2 features a 3D 2-fold interpenetrating framework with a self-penetrating (3,4,4)-connected {62.103.12}{63}2{64.8.10}2 topological net. [ABSTRACT FROM AUTHOR]

Transition metal organometallic reactions have become increasingly important in the synthesis of organic molecules. A new approach has been developed to introduce organometallic chemistry, along with organic and inorganic chemistry, at the foundational level. This change highlights applications of organometallic chemistry that have dramatically evolved in recent decades. With this development, a larger number of students have been reached than would typically be exposed to organometallic reactions. Modules are described that introduce transition metal organometallic compounds and reactions by analogy with thematically similar topics in general chemistry and organic chemistry. These topics are periodically reinforced by incorporation into organic synthesis problems. [ABSTRACT FROM AUTHOR]

ABSTRACT We have succeeded in the preparation of electrospun fibers of polystyrene incorporating a metallo-organic polymer of [Fe (II) (4-octadecyl-1,2,4-triazole)3(ClO4)2] n. The obtained fibers have diameters in the range 2-4 µm and show the characteristic spin-crossover transition associated with the metallo-organic polymer. The structure of both, polystyrene and the metallo-organic polymer, in the fibers was also studied. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 814-821 [ABSTRACT FROM AUTHOR]

Knowledge about the interactions between gas molecules and adsorption sites is essential to customize metalorganic frameworks (MOFs) as adsorbents. The dynamic interactions occurring during adsorption/desorption working cycles with several states are especially complicated. Even so, the gas dynamics based upon experimental observations and the distribution of guest molecules under various conditions in MOFs have not been extensively studied yet. In this work, a direct time-resolved diffraction structure envelope (TRDSE) method using sequential measurements by in situ synchrotron powder X-ray diffraction has been developed to monitor several gas dynamic processes taking place in MOFs: infusion, desorption, and gas redistribution upon temperature change. The electron density maps indicate that gas molecules prefer to redistribute over heterogeneous types of sites rather than to exclusively occupy the primary binding sites. We found that the gas molecules are entropically driven from open metal sites to larger neighboring spaces during the gas infusion period, matching the localized-to-mobile mechanism. In addition, the partitioning ratio of molecules adsorbed at each site varies with different temperatures, as opposed to an invariant distribution mode. Equally important, the gas adsorption in MOFs is intensely influenced by the gas--gas interactions, which might induce more molecules to be accommodated in an orderly compact arrangement. This sequential TRDSE method is generally applicable to most crystalline adsorbents, yielding information on distribution ratios of adsorbates at each type of site. [ABSTRACT FROM AUTHOR]

Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4′-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4′-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1–4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {44·62}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV–visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored. [ABSTRACT FROM AUTHOR]

Twelve Ir(iii) triscyclometalated compounds containing up to three azobenzene fragments on their structure have been synthesized based on photochromic 2-phenylpyridyl type ligands 1–4. These complexes are intended to study the possibility of transferring the photochromicity of the azobenzene fragment to the organometallic compound, and the effect of the substitution pattern, relative distance of the azobenzene to the metal centre, and number of azobenzenes on their properties. [ABSTRACT FROM AUTHOR]

Oxidation is one of the fundamental transformations in organic synthesis. The selective oxidation of inert substrates is interesting and important. In this review, the transition metal-catalyzed oxidation of methylarenes is discussed. Benzaldehyde, benzoic acid, benzyl alcohol, etc., were produced as the target products. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study, a Zr metal-organic framework (UIO-66) was synthesized with zirconium tetrachloride and terephthalic acid using the solvent method. Then various masses of 1-methylimidazolium-3-propylsulfonate hydrosulfate (PSMIMHSO4) were supported on the UIO-66 as catalysts, which were used for catalytic oxidative desulfurization. Sulfur removal using 400 mg of 40% PSMIMHSO4 supported on the UIO-66 of greater than 94% was obtained at 313 K for 20 min with an O/S molar ratio of 7:1. The results obtained in this work could provide useful information for the design of water-stable metal-organic frameworks with permanent porosity in applications of catalytic oxidative desulfurization. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

It is demonstrated that thin platinum films may be deposited onto smooth glass substrates using a materials printer and a propriety organometallic ink. Under optimised printing and subsequent thermal curing conditions, excellent film adhesion to the substrates was achieved for thicknesses of about 15 nm. The resistivity of the optimised films is observed to be a factor of less than 3 higher than pure bulk platinum at 300 K and exhibits a slightly smaller associated thermal coefficient of resistance. The resistivity parameters are found to be insensitive to the gaseous measurement environment which suggests that intercalated carbon regions within the films following the curing process have been largely eliminated. An analysis of the resistivity data indicates that electronic conduction is consistent with enhanced boundary scattering at granular structures that are introduced during multi-pass printing. A minimum electron mean free path of ~18 nm is deduced from the measured film topography. The presented work will find application in biosensor and fuel cell technologies. [ABSTRACT FROM AUTHOR]

A series of paramagnetic di(aryl)alkynylphosphine oxides 3a–c[PF6] featuring an open-shell [Fe(κ2-dppe)(η5-C5Me5)]+ endgroup were obtained by oxidation of their neutral Fe(ii) parents 3a–c, themselves obtained in a simple and nearly quantitative fashion from the corresponding Fe(ii) metallophosphines 1a–c. The new organometallic radicals were characterised by NMR and ESR and were shown to be perfectly stable in solution, in contrast to species such as 1a–b[PF6] which readily dimerise. [ABSTRACT FROM AUTHOR]

The synthesis of aliskiren intermediates was accomplished by attaching the 3,4-dialkoxyphenyl unit to precursor C-8 lactone-carboxylic acid derivatives using organometallic reagents. Totally different reactivities of the lactone-carboxylic acid chloride substrate towards organomagnesium and organoboron reagents were observed. [ABSTRACT FROM AUTHOR]

The postsynthetic modification of metal-organic frameworks is a promising new route for engineering optical centres and tuning the light emission properties of materials. Here, the postsynthetic modification of isoreticular metal-organic framework-3 (IRMOF-3) with ethyl oxalyl monochloride and ethyl acetoacetate followed by the chelation of trivalent lanthanide ions afforded efficient near-infrared (Nd3+) and visible (Eu3+ and Tb3+) light emitters. IRMOF-3 was used as an example owing to its highly porous crystalline structure and the presence of non-coordinating amino groups on the benzenedicarboxylate (bdc) linker, which are amenable to modification. The conversion of the amino groups was 100 and 65 % for ethyl oxalyl monochloride and ethyl acetoacetate, respectively. The materials were characterised by elemental analysis, powder X-ray diffraction, optical and scanning electron microscopy, Fourier transform infrared spectroscopy, and solution (1H) and (13C) solid-state nuclear magnetic resonance spectroscopy. The solid-state luminescence properties of Ln-modified IRMOF-3 were investigated at room temperature. The presence of the bdc aromatic ring, β-diketonates and oxamate enhanced the Ln3+ sensitization through ligand-to-metal energy transfer. The magnetic behaviour of all compounds was further analysed. The spin-orbit coupling and zero-field splitting parameters were evaluated by fitting the experimental magnetic susceptibility to the analytical expressions for the free Ln3+ ions. [ABSTRACT FROM AUTHOR]

Two novel cyclodiphosphazane cluster frameworks with Cu4X4 clusters as tetrahedral nodes and ferrocenyl cyclodiphosphazanes [Fe(η5-C5H4)2(PNtBu)2] as ditopic linkers have been synthesized. These frameworks having sodalite topology display a unique integration of porosity and redox activity and offer new opportunities for the synthesis of zeotype frameworks with soft phosphorus-based ligands. [ABSTRACT FROM AUTHOR]

An overview of the organometallic synthetic approaches to low-band-gap polymers for organic solar cells from 2008 to the present is reported. The key role of the synthetic methods in development of materials with increasing performances is outlined, with consideration not only of research laboratory criteria, but also of parameters relevant to mass production: synthetic complexity, amount and toxicity of reactants and by-products, and purification steps. The review is organized into sections covering the different organometallic polymerization reactions, also including olefin metathesis and the most recent results on direct arylation processes that appear particularly promising in terms of reduced synthetic complexity, costs, and byproducts. In the last section of the review, the discussed synthetic methods are reconsidered from the perspective of industrial scalability, which is one of the most critical issues for making OPV technology an effective route to solar energy exploitation. Interesting considerations are drawn on these basis, and directions for future developments in terms of requirements of the synthetic protocols are outlined. [ABSTRACT FROM AUTHOR]

An amine-functionalized metal-organic framework (MOF) has been employed as an effective fluorescent sensing platform for DNA detection and is capable of distinguishing complementary and mismatched target sequences with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Although reversible covalent activation of molecular hydrogen (H2) by transition-metal complexes is a common reaction, H2-mediated sophisticated reversible arrangements of organometallic frameworks have not yet been described. Herein, we report unusual organometallic transformations in solution that can be accomplished by uptake or release of H2. An efficient route for synthesizing air- and moisture-stable 16-electron M H2L H2-type metallacycles under very mild conditions has been developed. The new organometallic metallacycles favor the binding of small ligands such as MeCN, Cl- , CO, and pyridine. The reaction of a coordinatively unsaturated 16-electron M H2L2 H2-type macrocyclic complex featuring thione ligands with 1 atm of H2 leads to the isolation of a 18-electron M H2L H3-type cylinder, along with hydride species. Remarkably, the obtained mixture underwent loss of H2 in a facile manner upon heating to re-form the starting M H2L H2-type complex. A possible mechanism is proposed for the reversible transformations. [ABSTRACT FROM AUTHOR]

A Ni-catalyzed asymmetric reductive cross-coupling between vinyl bromides and benzyl chlorides has been developed. This method provides direct access to enantioenriched products bearing aryl-substituted tertiary allylic stereogenic centers from simple, stable starting materials. A broad substrate scope is achieved under mild reaction conditions that preclude the pregeneration of organometallic reagents and the regioselectivity issues commonly associated with asymmetric allylic arylation. [ABSTRACT FROM AUTHOR]

Organometallic iridium complexes bearing oxidatively stable chelate ligands are precursors for efficient homogeneous water-oxidation catalysts (WOCs), but their activity in oxygen evolution has so far been studied almost exclusively with sacrificial chemical oxidants. In this report, we study the electrochemical activation of Cp*Ir complexes and demonstrate true electrode-driven water oxidation catalyzed by a homogeneous iridium species in solution. Whereas the Cp* precursors exhibit no measurable O2-evolution activity, the molecular species formed after their oxidative activation are highly active homogeneous WOCs, capable of electrode-driven O2 evolution with high Faradaic efficiency. We have ruled out the formation of heterogeneous iridium oxides, either as colloids in solution or as deposits on the surface of the electrode, and found indication that the conversion of the precursor to the active molecular species occurs by a similar process whether carried out by chemical or electrochemical methods. This work makes these WOCs more practical for application in photoelectrochemical dyads for light-driven water splitting. [ABSTRACT FROM AUTHOR]

ABSTRACT The frontal ring opening metathesis polymerization of dicyclopentadiene using first and second generation Grubbs' catalysts is reported. To have sufficiently long pot lives, dimethylaminopyridine is added as an inhibitor. By choosing the proper compositions, it is possible to determine the ranges in which pure frontal polymerization occurs. A thorough study on the effect of the above components on the maximum temperatures reached by the front and on its velocities is performed. Namely, temperatures range from 164 to 205 °C depending on the type of catalyst and the above component ratios. Besides, front velocities range from 1.0 to 15.0 cm/min, which are one of the lowest and one of the highest values reported so far in any frontal polymerization experiment reported in literature. This finding allows the complete control of the frontal ring opening polymerization of dicyclopentadiene also in practical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2776-2780 [ABSTRACT FROM AUTHOR]

The synthesis of two pyridine-stabilised ansa-titanocene oxido complexes is described. Oxidation of the titanocene sources Cpb2Ti(η2-Me3SiC2SiMe3) (Cpb2 = bridged η5-cyclopentadienyl, 1a and 1b) with nitrous oxide yields corresponding oxido compounds 2a and 2b, respectively, in high yields. These can be hydrolysed to give dihydroxido complexes 3a and 3b, respectively, without the formation of by-products. The hydrolysis reaction was monitored by means of in situ IR spectroscopy. Hitherto unknown complexes 2a and 2b were fully characterised, and their molecular structures are reported in this paper. [ABSTRACT FROM AUTHOR]

A series of organic-metal chelate complexes of symmetric tetradentate Schiff base ligands derived from salicylaldehyde and 2-hydroxy-1-naphthaldehyde were designed and investigated. The combination of five nonconjugated flexible spacers and five conjugated rigid spacers with four salicylaldehyde derivatives provided a series of forty complexes. The series of blue to red photoluminescent complexes was investigated by UV/Vis absorption and luminescence spectroscopy in solution and in the solid state as well as cyclic voltammetry. The nature of the bridge in the ligand scaffold was determined to be the main parameter that influences the absorption and the emission color of the investigated zinc(II) complexes. [ABSTRACT FROM AUTHOR]

High-irradiance laser ionization time-of-flightmass spectrometry (LI-TOFMS), an established technique for elemental determination, has been applied for the analysis of metalloporphyrins. Many porphyrins and their metal complexes, being organometallic compounds, are hard to dissolve in general organic solvents, hampering the wider application of traditional mass spectrometric techniques. With LI-TOFMS, an environmentally friendly analytical strategy has been demonstrated, which is capable of matrix- and solvent-free analysis of metalloporphyrins, with advantages including direct solid sampling, ease of implementation, and avoidance of sample pre-treatment. Moreover, information about elemental composition, fragments, and intact molecules can be obtained simultaneously using LI-TOFMS, hence expediting the identification of metalloporphyrins. A comparative study of LI-, laser desorption ionization (LDI-), matrix-assisted laser desorption ionization (MALDI-) and electrospray ionization (ESI-) mass spectrometry (MS) has also been conducted. [ABSTRACT FROM AUTHOR]

In this paper, we study structural and morphological properties of metal-organic chemical vapour deposition-grown InGaN/GaN light emitting diode (LED) structures with different indium (In) content by means of high-resolution X-ray diffraction, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and current-voltage characteristic (I-V). We have found out that the tilt and twist angles, lateral and vertical coherence lengths of mosaic blocks, grain size, screw and edge dislocation densities of GaN and InGaN layers, and surface roughness monotonically vary with In content. Mosaic defects obtained due to temperature using reciprocal lattice space map has revealed optimized growth temperature for active InGaN layer of MQW LED. It has been observed in this growth temperature that according to AFM result, LED structure has high crystal dimension, and is rough whereas according to PL and FTIR results, bandgap energy shifted to blue, and energy peak half-width decreased at high values. According to I-V measurements, it was observed that LED reacted against light at optimized temperature. In conclusion, we have seen that InGaN MQW structure's structural, optical and electrical results supported one another. [ABSTRACT FROM AUTHOR]

This review summarizes the use of metal-organic frameworks (MOFs) as a versatile supramolecular platform to develop heterogeneous catalysts for a variety of organic reactions, especially for liquid-phase reactions. Following a background introduction about catalytic relevance to various metal-organic materials, crystal engineering of MOFs, characterization and evaluation methods of MOF catalysis, we categorize catalytic MOFs based on the types of active sites, including coordinatively unsaturated metal sites (CUMs), metalloligands, functional organic sites (FOS), as well as metal nanoparticles (MNPs) embedded in the cavities. Throughout the review, we emphasize the incidental or deliberate formation of active sites, the stability, heterogeneity and shape/size selectivity for MOF catalysis. Finally, we briefly introduce their relevance into photo- and biomimetic catalysis, and compare MOFs with other typical porous solids such as zeolites and mesoporous silica with regard to their different attributes, and provide our view on future trends and developments in MOF-based catalysis. [ABSTRACT FROM AUTHOR]