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Adsorption of metal‐organic complexes on metallic surfaces to produce well‐defined single site catalysts is a novel approach combining the advantages of homogeneous and heterogeneous catalysis. To avoid the "surface trans‐effect" a dome‐shaped molybdenum(0) tricarbonyl complex supported by an tolylazacalix[3](2,6)pyridine ligand is synthesized. This vacuum‐evaporable complex both activates CO and reacts with molecular oxygen (O2) to form a Mo(VI) trioxo complex which in turn is capable of catalytically mediating oxygen transfer. The molybdenum tricarbonyl‐ and trioxo complexes are investigated in the solid state, in homogeneous solution and on noble metal surfaces (Cu, Au) employing a range of spectroscopic and analytical methods. [ABSTRACT FROM AUTHOR]

From reactions involving sodium molybdate and dianilines [2,2′-(NH2)C6H4]2(CH2)n (n = 0, 1, 2) and amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2, in the presence of Et3N and Me3SiCl, products adopting H-bonded networks have been characterized. In particular, the reaction of 2,2′-diaminobiphenyl, [2,2′-NH2(C6H4)]2, and 2-aminoterephthalic acid, H2NC6H3-1,4-(CO2H)2, led to the isolation of [(MoCl3[2,2′-N(C6H4)]2}{HNC6H3-1-(CO2),4-(CO2H)]·2[2,2′-NH2(C6H4)]2·3.5MeCN (1·3.5MeCN), which contains intra-molecular N–H∙∙∙Cl H-bonds and slipped π∙∙∙π interactions. Similar use of 2,2′-methylenedianiline, [2,2′-(NH2)C6H4]2CH2, in combination with 2-aminoterephthalic acid led to the isolation of [MoCl2(O2CC6H3NHCO2SiMe3)(NC6H4CH2C6H4NH2)]·3MeCN (2·3MeCN). Complex 2 contains extensive H-bonds between pairs of centrosymmetrically-related molecules. In the case of 2,2′ethylenedianiline, [2,2′-(NH2)C6H4]2CH2CH2, and anthranilic acid, 1,2-(NH2)(CO2H)C6H4, reaction with Na2MoO4 in the presence of Et3N and Me3SiCl in refluxing 1,2-dimethoxyethane afforded the complex [MoCl3{1,2-(NH)(CO2)C6H4}{NC6H4CH2CH2C6H4NH3}]·MeCN (3·MeCN). In 3, there are intra-molecular bifurcated H-bonds between NH3 H atoms and chlorides, whilst pairs of molecules H-bond further via the NH3 groups to the non-coordinated carboxylate oxygen, resulting in H-bonded chains. Complexes 1 to 3 have been screened for the ring opening polymerization (ROP) of both ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) using solvent-free conditions under N2 and air. The products were of moderate to high molecular weight, with wide Ð values, and comprised several types of polymer families, including OH-terminated, OBn-terminated (for PCL only), and cyclic polymers. The results of metal-free ROP using the dianilines [2,2′-(NH2)C6H4]2(CH2)n (n = 0, 1, 2) and the amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2 under similar conditions (no BnOH) are also reported. The dianilines were found to be capable of the ROP of δ-VL (but not ε-CL), whilst anthranilic acid outperformed 2-aminoterephthalic acid for both ε-Cl and δ-VL. [ABSTRACT FROM AUTHOR]

The two-dimensional molybdenum carbide (Mo 2 CT x) has a similar electronic structure to platinum, which has the potential to be one of non-precious metals catalysts for hydrogen evolution reaction (HER). However, the preparation of Mo 2 CT x by conventional HF and LiF–HCl etching method inevitably introduces the –F and –Cl terminations on the surface, which adversely affect activity and stability. In this study, the LiCl–KCl–Li 3 N molten salt was used to treat Mo 2 CT x at 600 °C and atmospheric pressure and introduce nitrogen heteroatoms. After treated in LiCl–KCl–Li 3 N molten salt, the HER performance of nitrogen-doped Mo 2 CT x is improved compared with that of un-doped Mo 2 CT x , which should be attributed to the optimization of the electronic structure of N–Mo 2 CT x and lower hydrogen adsorption energy barrier. This simple molten salt method provides a way to modify non-precious metal HER catalyst and introduce nitrogen heteroatoms. The LiCl–KCl–Li 3 N molten salt was used to treat Mo 2 CT x at 600 °C and atmospheric pressure and introduce nitrogen heteroatoms. After treatment in LiCl–KCl–Li 3 N molten salt, the HER performance of nitrogen-doped Mo 2 CT x is improved compared with that of un-doped Mo 2 CT x , which should be attributed to the optimization of the electronic structure of N–Mo 2 CT x and lower hydrogen adsorption energy barrier. [Display omitted] • N-modified Mo 2 CT x MXene was prepared via molten salt modification strategy. • The N doping optimizes the electronic structure of Mo 2 CT x. • The improved catalytic performance and stability for Mo 2 CT x. • The molten salt method is simple, efficient, cost-effective, and environmentally friendly for modification. [ABSTRACT FROM AUTHOR]

In this study, molybdenum (Mo), tungsten (W), and mixed metal oxide and ‐nitride catalysts are synthesized via incipient wetness impregnation on silica support (SBA‐15) with a total target metal loading of 4 wt %. The effect of the Mo : W ratio on the non‐oxidative methane conversion, product selectivity, and coke formation is evaluated. The reduced Mo/SBA‐15 and MoW/SBA‐15 catalysts show higher CH4 conversion activity to benzene (selectivity of ~75.5 %) than for ethylene (selectivity of ~9.5 %) with a rather fast coke formation rate of 19–24 mgCoke gCat−1 h−1 without a clear influence of the Mo : W ratio. In contrast, the metal nitrides have a much smaller coke formation rate. The smallest rate of 0.45 mgCoke gCat−1 h−1 is achieved for the WN/SBA‐15 sample, which increases with the molybdenum content to 4.7 and 8.6 mgCoke gCat−1 h−1 for the MoWN(5 : 1) and MoN/SBA‐15 catalysts, respectively. There seems to be a yet unknown but negative correlation between the coke formation rate and the number of silanamine functional groups formed during the catalyst nitridation (Si−OH→≡Si−NH2→≡Si−NH−Si≡). The C2H4 selectivity is significantly increased with the relative amount of tungsten, with the highest C2H4 selectivity of 63 % for mixed‐metal nitride catalyst containing Mo : W ratio of 1 : 5. While the Mo/SBA‐15 the MoN/SBA‐15 achieve a C2H4 selectivity of less than 10 %. [ABSTRACT FROM AUTHOR]

The hydrodeoxygenation (HDO) of renewable fats or fatty acids into alkanes is a powerful measure to address energy and environmental crises. Molybdenum carbide-based catalysts are promising due to their platinum-like noble metal electronic properties. In this paper, Mo2C catalysts were prepared by one-step carbonization of amine molybdenum oxide (AMO) precursors using diamines with different carbon chain lengths as ligands. The physical and chemical properties and the HDO catalytic activity of the catalysts were investigated. The results indicate that as the carbon chain of diamines in the precursor increases, the carbon content of the catalysts in the surface and bulk phase increases. The Mo2C-12 catalyst exhibited excellent catalytic performance, with a palmitic acid conversion rate of 100% and an alkane selectivity of 96.6%, which are attributed to the smallest particle size, largest pore size, and synergistic effect of carbon. This work provides a simple and safe method for regulating the surface properties of Mo2C catalysts. [ABSTRACT FROM AUTHOR]

Nanoscience and nanotechnology have been undergoing the most explosive growth. However, well-controlled synthesis for manufacturing nanostructures still remains a challenge. In this work, we report a facile procedure to successively prepare the molybdenum dioxide (MoO2), molybdenum carbide (Mo2C) and molybdenum disulfide (MoS2) nanodots on carbon nanotubes (CNT). The prepared samples all possess super fine size. The electrocatalytic properties towards hydrogen evolution reaction (HER) of the three samples are investigated. The results indicate that the MoO2/CNT sample still exhibits very poor HER property, with 420 mV to drive a current density of 10 mA cm−2, while the Mo2C/CNT and MoS2/CNT samples show highly efficient HER performance, requiring overpotentials of 103 mV and 134 mV to accomplish the same current density, respectively. This work provides a very simple method for preparation of Mo-based nanodot catalysts which can be easily promoted for large-scale production. [ABSTRACT FROM AUTHOR]

Recently, simultaneous hydrotreatment of various petroleum fractions and plant feedstocks has been in demand. NiMo catalysts can be active in these processes. Therefore, supported NiMo oxide catalysts were prepared by impregnating an alumina support with Anderson's molybdenum salt (ammonium salt of nickel heteropolymolybdate (NH4)4NiMo6O24H6) and lithium carbonate. The prepared catalysts were tested in hydrodesulfurization (HDS) of thiophene and parallel HDS/HDO (hydrodeoxygenation) of 1-benzothiophene and octanoic acid. Experimental data showed a positive effect of lithium on the parallel HDS/HDO reactions and a negative effect on the HDS of thiophene. A significant effect of lithium on the acidity and reducibility of the NiMo/Al2O3 catalyst as well as the contribution of an Anderson-type heteropolycompound was demonstrated. [ABSTRACT FROM AUTHOR]

A new strain of Leptospirillum sp. Ksh-L was isolated from a dump-bioleaching system of the Kashen copper-molybdenum mine (South Caucasus). Ksh-L is an obligate chemolithoautotroph, capable of oxidizing ferrous iron (Fe2+). Cells are Gram-negative and vibrio- or spirillum-shaped of a 0.5–3 µm size. The optimal conditions for the growth are 35 °C and pH 1.6–1.8. Cu2+ and Zn2+ have different effects on the oxidizing ability of the Leptospirillum sp. Ksh-L culture depending on the phase of growth and concentration of Fe2+. Under the conditions of gradually increasing the concentration of copper in the medium, during 4–5 successive subculturing experiments, it was possible to obtain an adapted culture of Leptospirillum sp. Ksh-L, capable of growing in the medium in the presence of up to 400 mM Cu2+. A bioleaching experiment indicates that Ksh-L can efficiently oxidize chalcopyrite. However, the bioleaching of copper from chalcopyrite by Leptospirillum ferrodiazotropum Ksh-L increased about 1.8 times in association with At. thiooxidans ATCC 19377. Phylogenetic analysis based on 16S rRNA gene sequences (GenBank ID ON226845) shows that strain Ksh-L forms a single cluster into Group III. The strain possesses 99.59%, 99.52%, and 96.60% sequence similarity with the strains YTW-96-06, YTW-66-06, and Leptospirillum ferrodiazotrophum 5C in Group III, respectively. [ABSTRACT FROM AUTHOR]

A neutral silylyne complex of molybdenum was synthesized by the stepwise dehydrogenation method and its properties were compared with those of the tungsten analog. The complex takes a dimeric form as crystals but afford a monomer‐dimer equilibrium in solution. The replacement of the central metal from W to Mo led to a monomer dominant (~98 %) solution at room temperature. The monomer‐dimer dynamics was investigated based on thermodynamic parameters. The molybdenum silylyne complex underwent [2+2] cycloaddition with alkynes much faster than the tungsten analog. The reactions with organic azides led to the formation of the first example of silaiminoacyl complexes through [2+3] cycloaddition. The structures and bonding aspects of the products were clarified by multiple measurements and DFT calculations. [ABSTRACT FROM AUTHOR]

Two new β‐functionalized oxidomolybdenum(V) corroles, oxido[3‐formyl‐5,10,15‐triphenylcorrolato]molybdenum(V) (Mo‐1) and oxido[3‐dicyanovinyl‐5,10,15‐triphenylcorrolato]molybdenum(V) (Mo‐2) were synthesized and characterized by various spectroscopic techniques and electrochemical studies. Mo‐2 manifests splitted B bands due to x and y polarizations and highly red shifted longest B and Q bands due to the electron‐deficient nature of the dicyanovinyl group. EPR data showed that these complexes exhibit an axial compression with dxy1 configuration. DFT studies revealed that HOMO and LUMO orbitals are stabilized in Mo‐2 relative to Mo‐1. Mo‐1 exhibits two successive reversible reductions and two oxidation potentials in cyclic voltammetry. Surprisingly, Mo‐2 exhibits three successive reversible reductions and two oxidations; the one extra reduction could possibly be due to the reduction of the dicyanovinyl moiety. The catalytic activities of Mo‐1 and Mo‐2 for the oxidative bromination of various phenols using H2O2‐KBr‐HClO4 mixture in water have been explored and exhibited excellent activity at a very low catalyst loading of 0.0030 and 0.0028 mol%, respectively. Both synthesized β‐functionalized Mo(V) corroles manifest much higher conversion and TOF (59801–71174 h−1) for oxidative bromination of phenols relative to earlier reported meso‐functionalized Mo(V) corroles (20781–61646 h−1). Hence, Mo‐1 and Mo‐2 mimic vanadium bromoperoxidase (VBPO) and act as functional models for these catalytic applications. These catalysts were reused upto 3 cycles and showed conversion rate upto 82 % indicating their excellent thermal and chemical stabilities. [ABSTRACT FROM AUTHOR]

Series of linear tridentate PNPhPR‐ligands (R=Me, Et, Pln, Ph, Cyp, iPr, Cy, tBu) and molybdenum tricarbonyl complexes [Mo(CO)3PNPhPR] (R=Ph, Et, Cyp, iPr, Cy,) were synthesized and characterized using NMR‐, IR‐, and Raman spectroscopy as well as X‐ray crystallography. The influence of the different phosphine donor groups of the PNPhPR ligands on the bonding and activation of CO ligands is investigated. Importantly, all complexes are found to adopt a fac geometry, both in solution and in the solid state. This is in contrast to analogous complexes supported by PNHP ligands. DFT calculations reveal that the phenyl ring at the central amine function is the cause of the preferred geometry, hindering isomerization to a mer geometry. [ABSTRACT FROM AUTHOR]

The process mineralogy of a skarn-type refractory Cu-Mo ore in Peru was studied systematically by means of optical microscope, chemical mule-element analysis and phase analysis in order to establish reasonable flowsheet and beneficiation med of Cu-Mo ore. The results show that the mam useful elements of the ore are Cu and MO, and the grades are 0. 58% and 0. 019%, respectively. The mineral composition of the ore is complex, the man useful minerals are chalcopyrite, chalcocite, molybdenite, etc. The gangue mnerals are quartz, feldspar, mica, serpentine, template, chlorite, and tee. The copper and molybdenum minerals is fine, and often occurs along the edges, holes and cracks of pyrite or magnetite or gangue mineralize. A small amount of micro-fine chalcopyrite is distributed sparsely in gangue minerals, and the distillation relationship is complex, which affects the dressing recovery of copper and molybdenum [ABSTRACT FROM AUTHOR]

We newly designed and prepared a novel molybdenum complex bearing a 4‐[3,5‐bis(trifluoromethyl)phenyl]pyridine‐based PNP‐type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum‐imide complexes bearing various substituted pyridine‐based PNP‐type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification. [ABSTRACT FROM AUTHOR]

We newly designed and prepared a novel molybdenum complex bearing a 4‐[3,5‐bis(trifluoromethyl)phenyl]pyridine‐based PNP‐type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum‐imide complexes bearing various substituted pyridine‐based PNP‐type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification. [ABSTRACT FROM AUTHOR]

In this study, we report on the room-temperature characteristics of an impedance-type humidity sensor based on porous tin oxide/titanium oxide (SnO2/TiO2) composite ceramics modified with Mo and Zn. The SnO2/TiO2-based composites synthesized in the solid-state processing technique have been structurally characterized using X-ray diffraction, scanning electron microscopy, energy dispersive, and Raman spectroscopy. Structural analysis indicated the desired porous nature of the synthesized ceramics for sensing applications, with an average crystallite size in the nano range and a density of about 80%. The humidity-sensing properties were evaluated within a wide relative humidity range from 15% to 85% at room temperature, and the results showed that a better humidity response had a sample with Mo. This humidity-sensing material exhibits a linear impedance change of about two orders of magnitude at the optimal operating frequency of 10 kHz. Furthermore, fast response (18 s) and recovery (27 s), relatively small hysteresis (2.8%), repeatability, and good long-term stability were also obtained. Finally, the possible humidity-sensing mechanism was discussed in detail using the results of complex impedance analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stoichiometric amorphous MoOS 2 was prepared and tested in hydrogen evolution reaction (HER). • The structure of the oxysulfidic cluster was proposed based on EXAFS, Raman and DFT. • MoOS 2 possesses HER activity higher than MoS 2 , amorphous MoS 3 and a mixture of oxide and sulphide. • Oxygen has minor impact on the hydrogen desorption energy, dispersion and textural properties being more important factors. Amorphous molybdenum oxysulfide MoOS 2 obtained by acidification of aqueous MoO 2 S 2 2− solutions was structurally characterized and tested as a catalyst for hydrogen evolution reaction (HER). Raman, XPS and XAS characterizations show that the solid contains oligomers based on the Mo(V) core Mo 2 O 2 S 4 units, exposing dangling Mo O bonds and connected via Mo-S-Mo bridges. MoOS 2 demonstrated higher HER activity than reference catalysts including nanocrystalline MoS 2 , amorphous MoS 3 and MoS 2 /MoO 2 composite obtained by thermal decomposition of MoOS 2. DFT calculations suggest that introduction of oxygen adjacent to the disulfide bridges in the molybdenum coordination does not change significantly the free energy of hydrogen desorption, as compared with fully sulfided Mo x S y clusters. Higher HER catalytic activity of the MoOS 2 material was explained by abundance of disulfide S 2 2− moieties able to dissociate hydrogen and by fine dispersion of the material. [ABSTRACT FROM AUTHOR]

Reusability and durability of catalysts are main factors in biodiesel production. Fe3O4@SiO2‐APTES‐MoO2L2DHAPh catalyst was prepared in five steps. At first, Fe3O4 was synthesized and coated with silica (Fe3O4@SiO2). After that, the nanoparticles were functionalized by APTES (Fe3O4@SiO2‐APTES). In following, DHAPh ligand was anchored covalently onto the surface of aminated magnetic nanoparticles (Fe3O4@SiO2‐APTES‐LDHAPh), and at the end, DHAPh ligand was metalled by MoO2(acac)2 salt (Fe3O4@SiO2‐APTES‐MoO2L2DHAPh). The catalyst was characterized with analytical techniques such as FT‐IR, SEM, TEM, XRD, XPS, VSM, ICP, EDX, NH3‐TPD, and TGA. This novel catalyst with acidic and basic sites was used in (trans)esterification reaction for biodiesel production of rapeseed and other oils. The biodiesel yield of rapeseed, soybean, sunflower, and used frying oils was attained 97%, 98%, 96%, and 87%, respectively, under optimized reaction conditions, such as 0.1 mol% amount of catalyst, 0.05 mmol KOH as methanol activator, a short reaction time of 2 h, and methanol to oil ratio of 3:1 at room temperature. The conversion of oil to methyl ester biodiesel was confirmed by FT‐IR, 1H NMR, and GC‐MS analysis. The leaching and reusability tests of the prepared catalyst were checked, which displayed the biodiesel production proceeded via a heterogeneous pathway. Also, this catalyst can be reused for 11 cycles without tangible loss in its catalytic activity. The mentioned heterogeneously homogenized nanocatalyst has the main benefits such as easy reusability, high activity, and selectivity with acidic and basic sites that makes it a potential candidate for both esterification and (trans)esterification of low quality feedstock for low cost biodiesel production. [ABSTRACT FROM AUTHOR]

In this study, we present a methodology for synthesizing aza‐heterocyclic compounds using N‐tosylhydrazones as key reagents. Our primary objective was to obtain six or seven‐membered ring heterocycles; however, we unexpectedly observed the formation of bi‐indole compounds in high yields. Furthermore, our synthetic pathway enables modifications at the C3 or C2 position of the indole, leading to the formation of the respective 3′‐phenyl‐2′‐biindole or carbazole derivatives. [ABSTRACT FROM AUTHOR]

The chemistry of transition metal clusters has been intensively developed in the last decades, leading to the preparation of a number of compounds with promising and practically useful properties. In this context, the present work demonstrates the preparation and study of the reactivity, i.e., the possibility of varying the ligand environment, of new square pyramidal molybdenum chalcogenide clusters [{Mo5(μ3-S)i4(μ4-S)i(μ-pz)i4}(pzH)t5]1+/2+ (pzH = pyrazole, i = inner, t = terminal). The one-step synthesis starting from the octahedral Mo6Br12 cluster as well as the substitution of the apical pyrazole ligand or the selective bromination of the inner pyrazolate ligands were demonstrated. All the obtained compounds were characterized in detail using a series of physicochemical methods both in solid state (X-ray diffraction analysis, etc.) and in solution (nuclear magnetic resonance spectroscopy, mass spectrometry, etc.). In this work, redox properties and absorption in the ultraviolet-visible and near-infrared region of the obtained compounds were studied. [ABSTRACT FROM AUTHOR]

The first neutral and cationic Mo imido alkylidene cyclic alkyl amino carbene (CAAC) complexes of the general formulae [Mo(N−Ar)(CHCMe2Ph)(X)2(CAAC)] and [Mo(N−Ar)(CHCMe2Ph)(X)(CAAC)][B(ArF)4] (X=Br, Cl, OTf, OC6F5; CAAC=1‐(2,6‐iPr2‐C6H3)‐3,3,5,5‐tetramethyltetrahydropyrrol‐2‐ylidene) have been synthesized from molybdenum imido bishalide alkylidene DME precursors. Different combinations of the imido and "X" ligands have been employed to understand synthetic peculiarities. Selected complexes have been characterized by single‐crystal X‐ray analysis. Due to the pronounced σ‐donor/π‐acceptor characteristics of CAACs, the corresponding neutral and cationic molybdenum imido alkylidene CAAC complexes do not require the presence of stabilizing donor ligands such as nitriles. Calculations on the PBE0‐D3BJ/def2‐TZVP level for PBE0‐D3BJ/def2‐SVP optimized geometries revealed partial charges at molybdenum similar to the corresponding molybdenum imido alkylidene N‐heterocyclic carbene (NHC) complexes with a slightly higher polarization of the molybdenum alkylidene bond in the CAAC complexes. All cationic complexes have been tested in olefin metathesis reactions and showed improved activity compared to the analogous NHC complexes for hydrocarbon‐based substrates, allowing for turnover numbers (TONs) up to 9500 even at room temperature. Some Mo imido alkylidene CAAC complexes are tolerant towards functional groups like thioethers and sulfonamides. [ABSTRACT FROM AUTHOR]

A new compound, K5[(Mo3.2W1.8)O11](PO4)3[(P0.5Mo0.5)O4], was synthesized via solid-state reaction and its crystal structure was determined by single-crystal X-ray diffraction. This compound crystallizes in the space group Pnma, with a = 9.0360(4) Å, b = 10.1603(4) Å, c = 26.1538(12) Å and V = 2401.14(18) Å3. The structure consists of a corner-sharing MO6–TO4 (M = Mo, W; T = P, Mo) polyhedral connection arranged to form an ordered packing of ∼14.9 Å-thick layers parallel to (001). The stacking of the layers forms trigonal, tetragonal and hexagonal channels. XPS study reveals the presence of W at the hexavalent state only, whereas Mo appears as a mixed-valent species (Mo6+, Mo5+ and Mo4+). Magnetic susceptibility reveals the occurrence of a relevant antiferromagnetic coupling and is consistent with the presence of reduced metal species as indicated by the XPS results. [ABSTRACT FROM AUTHOR]

The low absorption of biological substances and living tissues in the red/near-infrared region (therapeutic window) makes luminophores emitting in the range of ~650–1350 nm favorable for in vitro and in vivo imaging. In contrast to commonly used organic dyes, inorganic red/NIR emitters, including ruthenium complexes, quantum dots, lanthanide compounds, and octahedral cluster complexes of molybdenum and tungsten, not only exhibit excellent emission in the desired region but also possess additional functional properties, such as photosensitization of the singlet oxygen generation process, upconversion luminescence, photoactivated effects, and so on. However, despite their outstanding functional applicability, they share the same drawback—instability in aqueous media under physiological conditions, especially without additional modifications. One of the most effective and thus widely used types of modification is incorporation into silica, which is (1) easy to obtain, (2) biocompatible, and (3) non-toxic. In addition, the variety of morphological characteristics, along with simple surface modification, provides room for creativity in the development of various multifunctional diagnostic/therapeutic platforms. In this review, we have highlighted biomedical applications of silica-based materials containing red/NIR-emitting compounds. [ABSTRACT FROM AUTHOR]

A series of molybdenum(II) compounds [(η5‐Cp')Mo(CO)2(L2)][BF4] (Cp'=C5H4(CH2)2SPh, C9H6(CH2)2OMe, L2=N,N‐chelating ligand) have been synthesized and characterized by spectroscopic and analytical methods including X‐ray crystallography. The in vitro assay on human leukemia cells MOLT‐4 has shown that the substitution in the π‐ligand in combination with suitable N,N‐chelating ligand can lead to species with cytotoxicity considerably higher than reported to cisplatin. Unusually high activity was observed for compounds bearing phenanthroline ligands [{η5‐C9H6(CH2)2OMe}Mo(CO)2(3,4,7,8‐Me4phen)][BF4] (IC50=0.7±0.3 μM) and [{η5‐C9H6(CH2)2OMe}Mo(CO)2(4,7‐Ph2phen)][BF4] (IC50 values 0.8±0.4 μM). [ABSTRACT FROM AUTHOR]

Integrating various active sites into a multi-component system might significantly enhance the oxygen evolution reaction (OER) performance. Herein, the as-prepared iron-molybdenum nitride/molybdenum oxide (Fe-Mo5N6/MoO3-550) composite electrocatalyst under optimum conditions demonstrates excellent electrocatalytic performance toward OER and reaches current densities of 10 and 20 mA cm−2 at overpotentials of 201 and 216 mV, respectively. The OER performance of Fe-Mo5N6/MoO3-550 exceeds that of most previously reported electrocatalytic systems. The significant improvement in the OER performance is ascribed to a combination of mechanisms. The strong electronic interactions among the Fe, Mo5N6 and MoO3 species can accelerate the OER reaction kinetics, which contributes to the OER performance. This work provides new insights into the construction of efficient electrocatalytic materials with inexpensive metals. [ABSTRACT FROM AUTHOR]

The C−C bond formation between C1 molecules plays an important role in chemistry as manifested by the Fischer–Tropsch (FT) process. Serving as models for the FT process, we report here the reactions between a neutral AlI complex (MeNacNac)Al (1, MeNacNac=HC[(CMe)(NDipp)]2, Dipp=2,6‐diisopropylphenyl) and various isocyanides. The step‐by‐step coupling mechanism was studied in detail by low‐temperature NMR monitoring, isotopic labeling, as well as quantum chemical calculations. Three different products were isolated in reaction of 1 with the sterically encumbered 2,6‐bis(benzhydryl)‐4‐Me‐phenyl isocyanide (BhpNC). These products substantiate carbene intermediates. The reaction between 1 and adamantyl isocyanide (AdNC) generated a trimerization product, and a corresponding carbene intermediate could be trapped in the form of a molybdenum(0) complex. Tri‐, tetra‐, and even pentamerization products were isolated with the sterically less congested phenyl and p‐methoxyphenyl isocyanides (PhNC and PMPNC) with concurrent construction of quinoline or indole heterocycles. Overall, this study provides evidence for carbene intermediates in FT‐type chemistry of aluminium(I) and isocyanides. [ABSTRACT FROM AUTHOR]

Several studies have revealed that the glass transition temperature (T g) of polymer nanocomposites (PNCs) may change upon the loading of even a small number of nanoparticles (NPs). However, the exact phenomenon behind such shifting in T g is still not well known. This study uses experimental and MD simulation approaches to explore the physics of the T g of polyaniline (PANI) nanocomposite with molybdenum carbide (Mo 2 C) nanoparticles at different weight percentage loading of NPs. The experimental study shows that, at a lower wt-% loading of NPs, the T g of the resulting PNCs decreases slowly, and above a particular loading wt-%* (30 wt-%), the depression in T g becomes more serious. The SEM images show that for wt-% < wt-%*, NPs remain diffuse in the polymer matrix, and for wt-%t > wt-%* a large number of NPs surround the polymer. The MD simulation reveals a slow increase in the diffusion of polymer and NPs for wt-% < wt-%* and a sudden increase for wt-%t > wt-%*. The measurement of the radius of gyration of the polymer reveals swelling of the polymer for wt-% < wt-%* and contraction of the polymer for wt-%t > wt-%*. Moreover, the variations of the diffusion constants and the radius of gyration of the polymer are consistent with the T g behaviour of PNCs. [ABSTRACT FROM AUTHOR]

The reaction of cyclopentaphosphine cyclo‐(P5Ph5) (1) with ketones (acetone and cyclooctanone) in the presence of [Mo(CO)4(cod)] (cod=cycloocta‐1,5‐diene) led to air‐stable trinuclear complexes in which the bis‐phosphanido ligands (PPh−PPh−PPh−PPh−CMe2O−PPh)2− (complex 2) and (PPh−PPh−PPh−PPh−C(CH2)7O−PPh)2− (complex 3) bridge a Mo(CO)3−Mo(CO)3 unit. This extends the reaction of 1 with transition metal carbonyl complexes to further substrates and represents the first examples of insertion of carbonyl compounds into the P−P bond of cyclic oligophosphorus compounds. Complexes 2 and 3 have been characterized by 31P NMR spectroscopy and single crystal X‐ray diffraction. Furthermore, the thermal properties of the obtained complexes have been studied by differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC). [ABSTRACT FROM AUTHOR]

Single-phase tungsten-doped lanthanum molybdenum oxide (La2MoWO9) ceramic powders were synthesized using the complex polymerization technique. Porous ceramic pellets were obtained by thermally removing graphite, which served as a pore former. The porous pellets were then impregnated with molten eutectic lithium-sodium-potassium carbonates. The energy dispersive X-ray analysis and scanning electron microscopy (FEG-SEM) images of the external and fracture surfaces of the La2MoWO9-(Li,Na,K)2CO3 composite dual-phase membrane revealed the percolation of the carbonate mixture through the pores. Electrochemical impedance spectroscopy measurements conducted at temperatures below and above the melting point of the eutectic carbonate composition demonstrated the contributions of oxygen and carbonate ions to the ionic conductivity of the dual membrane. The electrical conductivity of the carbonate ions within the membrane was continuously monitored for over 1300 h with negligible degradation, implying that the membrane could be used for long-term monitoring of CO2 without aging effects. A comparison of FEG-SEM images taken before and after this endurance test suggested minimal fouling, indicating that the membrane could potentially replace similar zirconia- and ceria-based composite membranes. [ABSTRACT FROM AUTHOR]

Molybdenum(V)-mediated cleavage of C(sp2)–Se bond and C(sp2)–H bond as well as intramolecular oxidative C(sp2)–Se coupling reaction of phenylselenyl-functionalized arenes or heterocycles has been developed. Three kinds of benzoselenophene frameworks were constructed through this reaction with yields up to 94%. This new C(sp2)–Se bond-switching methodology may provide a new strategy for interesting applications of phenylselenyl-substituted aromatic compounds in the synthesis of selenium-containing heterocycles and natural products. [ABSTRACT FROM AUTHOR]

Highly efficient catalysts play an important role in the effective use of biomass oil to produce clean fuel. In this work, pure‐phase Ni−Mo bimetallic nitrides (Ni2Mo3N and Ni3Mo3N) with different stoichiometric ratios are prepared by temperature‐programmed nitridation of the metal oxide precursors in ammonia, which are investigated in the hydrodeoxygenation of methyl palmitate in the fixed‐bed reactor at moderate conditions. The physical and chemical properties of catalysts were evaluated by H2‐TPR, XRD, SEM, TEM, XPS, and CO chemisorption. The Ni2Mo3N catalyst presents the best methyl palmitate hydrogenation activity (con.%=95.4 %) and the maximum hexadecane selectivity (95.0 %), which is obviously higher than those of Ni3Mo3N and Mo2N catalysts. By introducing transition metal Ni into the Mo2N lattice to form nickel‐molybdenum bimetallic nitride, the lattice structure and electronic structure of the Mo active center have been changed, which greatly enhances the hydrodeoxygenation performances for the transformation of biomass oil to clean fuel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Films on electropolished substrates have higher absorbances and are more homogeneous. • By combining absorbance and emittance, passivation results in greater solar selectivity. • SiO 2 deposition on Mo films increased their absorbances. • The SiO 2 layer increased the surface roughness of the coatings. • The SiO 2 layer improved the surface homogenization of the films. The thermal performance of solar collectors depends on the selective coverage over their absorbing plate, known as selective surfaces, which determines the heat gain and loss of the equipment. Different materials and layering arrangements can be used for the production of selective surfaces. This work proposes the production of selective surfaces of molybdenum (Mo) and silica (SiO 2) evaluating the influence of the type of substrate treatment (chemical cleaning, passivation and electropolishing) on this performance. The results obtained in UV–Visible and Near Infrared Spectrophotometry showed that the surface absorptance is higher for Mo and Mo/SiO 2 films on electropolished surfaces compared to treatments with acid and hexane. The highest absorptance reached was 98.10% for a Mo/SiO 2 film (45.023 nm), on electropolished substrate. However, the highest solar selectivity was obtained from the Mo/SiO 2 film on a passivated substrate. X-ray diffraction (XRD) exhibited peaks characteristic of the metallic Mo phase, and the presence of silica in the amorphous and crystalline phases in the form of quartz was also verified. The results obtained in Optical Profilometry and Atomic Force Microscopy (AFM) indicate that the absorptance of the samples is influenced by the roughness of the substrates. [ABSTRACT FROM AUTHOR]

We report a simple method involving optimization of oxygen partial pressure (OPP) in the after-growth annealing process of MoOx nanostructured thin films that results in a better field emitter with a low turn-on field and a high field enhancement factor. A ≈250 nm thick molybdenum oxide thin film has been synthesized on Si(100) substrates by the physical vapor deposition technique. The as-deposited thin films are annealed at 600 °C for 30 min in different OPPs, such as ≈2.1 × 10−9 Pa, ≈2.1 × 10−1 Pa, and ≈2.1 × 104 Pa. The effect of postannealing on the morphology, crystal structure, stoichiometry, elemental concentration, optical and local work function of the samples has been investigated using scanning electron microscopy, atomic force microscopy, resonant Rutherford backscattering spectrometry, and X-ray diffraction methods. As-deposited amorphous thin films transformed to granular MoO2 and layeredlike α-MoO3 nanostructures after annealing at 600 °C for 30 min in the OPP of ≈2.1 × 10−9 Pa and ≈2.1 × 104 Pa, respectively. The optical bandgap and the local work function are increased from 2.60 eV to 3.22 eV and 5.12 eV to 5.76 eV, whereas the field emission turn-on field is decreased from 6.6 V/μm to 4.7 V/μm for 10 μA/cm2 with increasing OPP from ≈2.1 × 10−9 Pa to ≈2.1 × 104 Pa. [ABSTRACT FROM AUTHOR]

The regulation of redox and acid–base properties of MgO-Al2O3 systems has been carried out during the synthesis by introducing bifunctional additives of molybdate and tungstate ions. Doping with Mo and W compounds leads to an increase in the activity of Mg-Al-oxide catalysts and the selectivity of 1-butanol formation in the ethanol condensation process due to an increase in the concentration of the sites of ethanol dehydrogenation and acetaldehyde aldol condensation. [ABSTRACT FROM AUTHOR]

The development of advanced nanomaterials is urgent for electrocatalytic energy conversion applications. Recently, 2D nanomaterial‐derived heterogeneous electrocatalysts have shown great promise for both fundamental research and practical applications owing to their extremely high surface‐to‐volume ratio and tunable geometric and electronic properties. Because of their unique electronic structure and physicochemical properties, molybdenum (Mo)‐based 2D nanomaterials are emerging as one of the most attractive candidates among the nonprecious materials for electrocatalysts. This review provides a comprehensive overview of the recent advances in the synthesis and modulation of 2D Mo compounds for applications in electrocatalytic energy conversion. The categories based on different compositions and corresponding synthetic approaches of 2D Mo compounds are first introduced. Subsequently, various atomic/plane/synergistic engineering strategies, along with catalytic optimization in the electrochemical process that involves the cycles of water, carbon, and nitrogen, are discussed in detail. Finally, the current challenges and future opportunities for the development of 2D Mo‐based electrocatalysts are proposed with the goal of shedding light on these promising 2D nanomaterials for electrocatalytic energy conversion. [ABSTRACT FROM AUTHOR]

Treatment of phosphino(imino)pyridine (PIP) molybdenum cyclooctadiene (COD) complexes [(PIP)Mo(COD)] with dihydrogen in the presence of benzene selectively furnished the molybdenum cyclohexadienyl hydrides [(PIP)MoH(η5‐C6H7)], which are precatalysts for the hydrogenation of benzene to cyclohexane. [(PIP)MoH(η5‐C6H7)] arises from a rarely observed insertion of benzene into a molybdenum‐hydride bond, a key step in the molybdenum‐catalyzed homogeneous hydrogenation of arenes. The reaction with toluene afforded a single isomer of the corresponding molybdenum cyclohexadienyl hydride while para‐xylene predominantly formed the molybdenum η6‐arene complex with the insertion product being a minor component. Addition of carbon monoxide to a cyclohexane‐d12 solution of [(PIP)MoH(η5‐C6H7)] liberated cyclohexadiene, providing experimental support for a higher kinetic barrier for the subsequent steps en route to cycloalkanes. [ABSTRACT FROM AUTHOR]

Treatment of phosphino(imino)pyridine (PIP) molybdenum cyclooctadiene (COD) complexes [(PIP)Mo(COD)] with dihydrogen in the presence of benzene selectively furnished the molybdenum cyclohexadienyl hydrides [(PIP)MoH(η5‐C6H7)], which are precatalysts for the hydrogenation of benzene to cyclohexane. [(PIP)MoH(η5‐C6H7)] arises from a rarely observed insertion of benzene into a molybdenum‐hydride bond, a key step in the molybdenum‐catalyzed homogeneous hydrogenation of arenes. The reaction with toluene afforded a single isomer of the corresponding molybdenum cyclohexadienyl hydride while para‐xylene predominantly formed the molybdenum η6‐arene complex with the insertion product being a minor component. Addition of carbon monoxide to a cyclohexane‐d12 solution of [(PIP)MoH(η5‐C6H7)] liberated cyclohexadiene, providing experimental support for a higher kinetic barrier for the subsequent steps en route to cycloalkanes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of a fluorine-free hydrothermal method for the preparation of MoS 2 /Mo 2 CT x MXene. • Thioacetamide was used as the source of sulfide ions for the sulfidation of MXene. • Microwave-assisted hydrothermal treatment resulted in MoS 2 formation on the MXene surface. • Amorphous MoS 2 on the MXene surface enhanced its chemical stability. • MoS 2 /Mo 2 CT x exhibited superior catalytic activity for the hydrogen evolution reaction in alkaline medium. Synthesizing MXenes from M n+1 AX n (MAX) phases using hazardous hydrogen fluoride is a common and effective method. However, fluorine termination on the basal planes and edges of the resulting MXenes is undesirable for the electrocatalytic hydrogen evolution reaction (HER), while oxygen (O), hydroxyl (OH), and sulfur (S) termination favors this reaction. Herein, we unveil a simple fluorine-free exfoliation and two-step vulcanization method for synthesizing molybdenum sulfide-modified molybdenum carbide (MoS 2 /Mo 2 CT x MXene, T = OH, O, S) for the HER in alkaline medium. Microwave-assisted hydrothermal treatment of the MAX phase (Mo 3 AlC 2) with sodium hydroxide-sodium sulfide as an etching solution and thioacetamide as a source of sulfide ions enabled the selective dissolution of the aluminum (Al) layer and sulfidation of the surface Mo atoms to form amorphous MoS 2. Thus, the vulcanization of Mo 2 CT x MXene resulted in the formation of MoS 2 /Mo 2 CT x MXene. The MoS 2 formed on the surface of Mo 2 CT x provided enhanced stability by preventing oxidation. MoS 2 /Mo 2 CT x exhibited enhanced electrocatalytic activity toward the HER, mainly due to the O, OH, and amorphous MoS 2 functionalities. The MoS 2 sites on the surface exhibited an overpotential of 110 ± 7 mV at a current density of 10 mA cm−2 as a result of enhanced charge transfer and mass transfer. Thus, the sulfidation method demonstrated herein is capable of producing amorphous MoS 2 structures on Mo 2 CT x MXene, which could be applied for the surface modification of other molybdenum-based nanomaterials or electrocatalysts to improve stability and enhance electrocatalytic activity. [ABSTRACT FROM AUTHOR]

In the course of synthesis and studies of properties of nanomaterials based on layered molybdenum disulfide, it becomes necessary to perform rapid elemental analysis and to return the material to customer promptly. In some cases, to improve catalytic or magnetic properties, it is required to modify nanoparticles of molybdenum disulfide by metal compounds. A procedure is proposed for rapid X-ray fluorescence determination of molybdenum and cobalt in the content range of 10–50% in similar compounds by a bulk method without dilution. Analytical signals have been measured at the wavelengths of the MoKα and CoKα lines using a VRA-30 spectrometer (Carl Zeiss, Germany, X-ray tube with Rh anode). The content of the metals has been calculated using the derived equations of interrelations. The error of determination is ±2.7% (abs.) for Mo and ±1.4% (abs.) for Co. Correctness of the procedure has been confirmed for a batch of synthesized compounds by comparison with XRF results with dilution. This rapid method makes it possible to simplify the procedure and to reduce the time of analysis by more than 4 times; here, the sample is retained and can be used for further research. [ABSTRACT FROM AUTHOR]

Molecular molybdenum complexes with sulfur donor ligands are generally studied as soluble model compounds for molybdenum enzymes essential for life. The dioxidomolybdenum(VI) complex with tetradentate aminobisphenolate ligand undergoes a reaction with thionation reagent P2S5 or its organic derivative, Lawesson's reagent, to yield stable Mo(IV) aminobisphenolate complexes, where pristine oxido ligands have been replaced by bidentate sulfur donors tetrasulfide, S42− or (4-methoxyphenyl)phosphonotrithioate residue derived from Lawesson's reagent. This is in contrast to the behaviour of analogous dioxidotungsten(VI) complex, which, under similar conditions, yields W(VI) S2 systems. The overall cis,trans,cis geometry of the parent dioxidomolybdenum(VI) aminobisphenolate is retained, namely, the neutral nitrogen donors are in cis positions, phenolate oxygens are trans to each other and sulfur donors are cis. Although formally Mo(IV), thus d2 system, the studied complexes have diamagnetic singlet electron configurations as a result of the axially compressed octahedral structures. [ABSTRACT FROM AUTHOR]

Molybdenum carbide is a noble-metal-like material, which shows great potential in many applications. The conventional Temperature-Programmed-Reduction (TPRe) method uses carbonaceous gases to carburize with molybdenum precursors, which has made a significant progress but still hard to scale up. In this work, molybdenum carbides were prepared by carburization of ammonium molybdenum molybdate on cellulose, g-C 3 N 4 , MWCNTs and sodium lignosulfonate without using any gaseous carbon source. Moreover, the formation of molybdenum carbide was subjected to in-depth investigation by using an in situ Simultaneous Thermal Analyzer – Quadrupole Mass Spectrometry coupling System. The technique revealed that the solid carbon carriers do have a great effect on the formation of molybdenum carbides. Furthermore, various characterization methods such as XRD, SEM, CO-TPD, FTIR and organic element analysis (OEA) were also applied to investigate the property of prepared molybdenum carbides. The results suggested that the prepared molybdenum carbides with CEL, MWCNTs and SLF as carbon supports could retain the skeleton and porous structure of a solid carbon carrier, and the prepared molybdenum carbides with g-C 3 N 4 as a carbon support could generate a new three-dimensional (3D) structure support, and the composition of carriers would also have an impact on the adsorption and physicochemical properties of molybdenum carbides. Synthesis and Characterization of Molybdenum Carbide Catalysts on Different Carbon Supports [Display omitted] • Abundant and cheap organic solid carbon was used as carrier and carbon source. • Molybdenum carbides were prepared without using any gaseous carbon source and hydrogen. • The formation of molybdenum carbide on the carbon supports was systematically investigated. [ABSTRACT FROM AUTHOR]

Tetrakis(dithiocarboxylato)molybdenum(IV) complexes of the type Mo(S2CR)4 (R = Me, Et, iPr, Ph) were synthesized, characterized, and prescreened as precursors for aerosol assisted chemical vapor deposition (AACVD) of MoS2 thin films. The thermal behavior of the complexes as determined by TGA and GC-MS was appropriate for AACVD, although the complexes were not sufficiently volatile for conventional CVD bubbler systems. Thin films of MoS2 were grown by AACVD at 500 °C from solutions of Mo(S2CMe)4 in toluene. The films were characterized by GIXRD diffraction patterns which correspond to a 2H-MoS2 structure in the deposited film. Mo–S bonding in 2H-MoS2 was further confirmed by XPS and EDS. The film morphology, vertically oriented structure, and thickness (2.54 μm) were evaluated by FE-SEM. The Raman E12g and A1g vibrational modes of crystalline 2H-MoS2 were observed. These results demonstrate the use of dithiocarboxylato ligands for the chemical vapor deposition of metal sulfides. [ABSTRACT FROM AUTHOR]

Among the schemes to improve the efficiency of electrochemical hydrogen evolution reaction (HER), molybdenum carbides are seen as suitable candidates to replace noble metal electrocatalysts because of their Pt-like d-band center and proper adsorption of intermediate hydrogen species (Hads). Iodine is identified to form I−Hads bond when used as a single-atom electrocatalyst of HER, thereby improving the performance. However, there is no report of combining iodine atoms with molybdenum carbides. We successfully designed a polyoxomolybdate-based precursor molecule which included octamolybdate anions and iodonium cations. After pyrolysis treatment, iodine-doped molybdenum carbide nanocomposite was obtained and exhibited enhanced HER property. This work can verify that iodine atoms can synergistically improve the electrochemical performance of transitional metal nanocomposites, and provide a new insight for the design of advanced HER electrocatalysts. [ABSTRACT FROM AUTHOR]

A composite of Mo2C nanoparticles dispersed onto a nitrogen and sulfur co-doped carbon scaffold (Mo2C/N,S-C) was prepared by a simple and environmentally friendly method of one-pot annealing of MoCl5, urea, and lignosulfonate under a N2 atmosphere at 700 °C. Lignosulfonate, a by-product of the sulfite pulping process, was employed as a feedstock to fabricate the S-doped carbon scaffold and carbide simultaneously, and urea acted as a nitrogen source for N-doping to carbon. The as-prepared Mo2C/N,S-C catalyst showed high performance for the hydrogen evolution reaction (HER), with a small overpotential of 105 mV at 10 mAcm−2, and good stability for 3000 cycles. The improved HER performance of the Mo2C/N,S-C originated from the interplay between the highly active Mo2C nanoparticles and the N,S co-doped carbon scaffold with its high electrical conductivity and large surface area. Furthermore, N,S co-doping to carbon improved the hydrophilicity of the catalyst surface, thus further enhancing the HER activity. [ABSTRACT FROM AUTHOR]

This work was motivated by the promising physiochemical properties and catalytic activity of molybdenum carbide. Thin films of molybdenum carbide were deposited on the mono-crystalline cubic Si (400) substrate by utilizing a 3.6 kJ dense plasma focus device (Mather-type) with multiple shots. The structure of the films was examined by X-ray diffraction (XRD). XRD results indicated the absence of crystalline film for 5 focus shots, while for increased numbers of focus shots, the emergence of Mo-C peaks in the orientations (120), (014) and (232) confirmed the formation of orthorhombic β-Mo2C polycrystalline films. Moreover, a small variation in the crystallite size was observed by increasing the number of focus shots. The presence of molybdenum and carbon was confirmed by energy-dispersive X-ray (EDX) analysis. Surface morphology was studied under scanning electron microscope (SEM). SEM micrographs revealed non-uniform films with some surface defects such as cracks and craters of micron size, and rough surface. Revealed by the ellipsometry technique, the film thickness increased by increasing the number of focus shots. The electric conductivity, measured by the four-point probe technique, was the highest for 10 focus shots. However, the films have some structural defects, low conductivity and impurities like silicon and silicon carbide, but it was the first ever successful attempt to deposit molybdenum-carbide (Mo2C) thin films using the dense plasma focus device. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple and cost-effective synthesis of MoS 2 @MWCNTs by wet chemical method. • The MoS 2 @MWCNTs has improved surface area attributed in its surface imperfections and defects. • The MoS 2 @MWCNTs selectively detects picric acid (PA) in the presence of common water and structurally analogues interferants. • The synthesized electrocatalyst shows lower LoD with wide linear range. • The recyclability, reproducibility, repeatability experiments prove efficacy of electrocatalyst and applied for real samples. Nitrophenols are industrially versatile yet environmentally detrimental compounds. Herein, we have synthesised molybdenum sulphide based dichalcogenide supported multiwalled carbon nanotubes i.e. MoS 2 @MWCNTs electrocatalyst by simple wet chemical method for PA determination. The successful decoration of MoS 2 over MWCNTs were confirmed by various characterizations techniques including scanning electron microscopy (SEM) shows MoS 2 layers grown on MWCNTs and having average size is –80 nm. Energy dispersive X-ray analysis (EDAX) reveals elements are homogenously distributed in nanocomposite. High resolution-transmission electron microscopy (HR-TEM) shows increase in average diameter after decoration of MoS 2 over MWCNTs from 30 nm to 70 nm. The Fourier transform infrared (FT-IR) analysis suggests the presence of Mo-S stretching frequency at 605 cm−1 in addition to hydroxyl, carbonyl, C–C, C–O stretching frequencies are also observed. In Raman spectrum from apart D and G bands, the characteristic intense bands E 2g 1 and A 1g of MoS 2 were pointed towards presence of molybdenum and sulphur. The X-ray diffraction (XRD) confirms synthesised electrocatalyst is in hexagonal crystal structure with P63/mmc space group. The X-ray photoelectron spectroscopy (XPS) reveals that for Mo 3d is found to be two characteristics peaks at 231.2 eV and 233.2 eV corresponds to Mo4+ 3d 3/2 and 3d 5/2 respectively. The peak at 229 eV corresponds to S 2s. Whereas, the signal appears at 162.7 eV, 165 eV, 169 eV and 170 eV shows sulphur is in 2S 3/2 and 2S5 /2 states. Electrochemical performance was examined by cyclic voltammetry (CV) tests. The Electrocatalyst is highly selective, having appreciable anti-interference property, lower limit of detection (LoD), i.e., 0.5 μM with wide linear range. The low R ct and high k⁰ pointed that MoS 2 @MWCNTs performed better towards electrochemical detection of PA. [ABSTRACT FROM AUTHOR]

Molybdenum( 0)- Tricarbonyl Complex Supported by anAzacalix- pyridine Ligand: Synthesis, Characterization, Surface Deposition and Conversion to a Molybdenum( VI)- Trioxo Complex with O2 [Extracted from the article]

• A new glycine-bisphenol molybdenum(VI) complex, SBA@AP-GDC-Mo, immobilized on ordered mesoporous silica was synthesized and fully characterized. • SBA@AP-GDC-Mo is an efficient and selective heterogenous catalyst for chemoselective oxidation of thioethers to sulfoxides and sulfones. • The advantages of SBA@AP-GDC-Mo include high activity under eco-friendly, mild conditions (e.g., room temperature, organic solvent-free or in ethanol) and reusability for at least four cycles. Herein we introduce a new glycine-bisphenol molybdenum(VI) complex, SBA@AP-GDC-Mo, immobilized on ordered mesoporous silica SBA-15 (Santa Barbara Amorphous) as an efficient and selective heterogenous catalyst. SBA@AP-GDC-Mo was fully characterized by Fourier transform-infra red (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), field emission-transmission electron microscopy (FE-TEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and Barrett–Joyner–Halenda (BJH) and Brunauer–Emmett–Teller (BET) adsorption isotherms. The catalytic performance of SBA@AP-GDC-Mo was evaluated in the chemoselective oxidation of sulfides to sulfoxides and sulfones and found to be superior to our previously reported diamine–bisphenol molybdenum(VI) catalyst. The advantages of SBA@AP-GDC-Mo include high activity and better chemoselectivity under mild and eco-friendly conditions (e.g., ambient temperature using aqueous or aqueous–ethanolic solutions), recyclable for at least four cycles and easier overall synthesis in good yields including tethering of the ligand to the support. [Display omitted] [ABSTRACT FROM AUTHOR]

The tungsten dinitrogen complex [W(N2)(PMe2PPPh2)] (2) (PMe2PPPh2 = [2-({bis[3-(diphenylphosphino)propyl]-phosphino}methyl)-2-methylpropane-1,3-diyl]bis(dimethylphosphine)) is synthesized and characterized by X-ray diffraction as well as IR and NMR spectroscopies, showing strong analogies to its molybdenum analogue [Mo(N2)(PMe2PPPh2)] (1). Whereas cyclic voltammetry studies indicate very similar redox potentials, detailed electrochemical and IR-spectroelectrochemical investigations reveal characteristic differences between 1 and 2 upon electrochemical oxidation in THF. Protonation of 2 with HBArF (BArF = tetrakis(3,5-bis(trifluoromethyl)-phenyl)borate) leads to the hydrazido(2-) derivative 3 which is spectroscopically characterized as well. In the presence of SmI2/H2O slightly overstoichiometric conversion of N2 to ammonia (2.75 equiv.) is observed. Although this is far below the activity of the Mo-complex 1, it renders 2 the first W complex to produce more than 2 equivalents of NH3 from N2 upon addition of protons and reductant. [ABSTRACT FROM AUTHOR]

The cyclopropanation of alkenes through the transition-metal-catalyzed decomposition of diazo compounds is a powerful and straightforward strategy to produce cyclopropanes. Nevertheless, the appeal of further application of this strategy is tempered by the potentially explosive nature of the diazo substrates. Therefore, it is highly desirable to develop sustainable and operationally safe surrogates for diazo compounds. In this Synpacts article, we discuss recent advances on the cyclopropane syntheses through the catalytic cyclopropanation of alkenes and metal carbenes generated in situ from nondiazo precursors as well as highlight our recent progress on the unprecedented molybdenum-catalyzed deoxygenative cyclopropanation reaction of 1,2-dicarbonyl or monocarbonyl compounds. [ABSTRACT FROM AUTHOR]

Tailored molybdenum(VI)‐oxo complexes of the form MoOCl2(OR)2(OEt2) catalyse olefin metathesis upon reaction with an organosilicon reducing agent at 70 °C, in the presence of olefins. While this reactivity parallels what has recently been observed for the corresponding classical heterogeneous catalysts based on supported metal oxide under similar conditions, the well‐defined nature of our starting molecular systems allows us to understand the influence of structural, spectroscopic and electronic characteristics of the catalytic precursor on the initiation and catalytic proficiency of the final species. The catalytic performances of the pre‐catalysts are determined by the highly electron withdrawing (σ‐donation) character of alkoxide ligands, OtBuF9 being the best. This activity correlates with both the 95Mo chemical shift and the reduction potential that follows the same trend: OtBuF9>OtBuF6>OtBuF3. [ABSTRACT FROM AUTHOR]