Search

An emissive organic–inorganic hybrid material is obtained by a cationic metathesis between a blue fluorescent tetraphenylethylene‐based salt: [TPEIm2]I2, and a red‐NIR phosphorescent octahedral molybdenum cluster compound: Cs2[Mo6I8(OCOC2F5)6]. As demonstrated by Single Crystal X‐Ray Diffraction, the hybrid [TPEIm2][Mo6I8(OCOC2F5)6] crystallizes as a 2:2 dimer and emits in the red‐NIR area. Its emission properties are studied in the solid state and once embedded in poly(methylmethacrylate) by steady state and time dependent photoluminescence spectroscopy. They are further compared to the case in which the two starting salts are directly integrated in the polymer matrix. Obtained nanocomposites show evanescent UV‐2A optical writing and reading behavior, with color contrasts depending on how emitters have been introduced. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is an essential micronutrient required for plant growth but is prone to leaching from neutral and alkaline soils. The use of slow-release Mo sources could potentially reduce leaching losses from soils and increase crop yields. In this study, we assessed mechanochemistry as a green method to produce slow-release Mo sources. Molybdenum compounds (MoO3 or (NH4)6Mo7O24·4H2O) were mechanochemically (MC) treated with ZnO to synthesize compounds with a Mo content of 1–36%. Reduced Mo solubility after MC treatment, compared to the initial Mo source, was obtained with the MoO3 source and these composites were used for co-compaction with macronutrient fertilizers. Macronutrient pellets with 0.2% Mo were compacted using the 4% Mo and 36% Mo (characterized as ZnMoO4) compounds. A column dissolution test showed that the 4% Mo compound in a macronutrient carrier (DAP and MAP) only released around 40% of the total Mo compared to 80% for a non-MC treated control over 72 h. Column leaching using two soils revealed that the release behavior of Mo was strongly related to the pH of the leachate, which was affected by both the soil pH and the macronutrient carrier. More Mo was released when the MC-treated compound was co-compacted with diammonium phosphate (DAP) compared to monoammonium phosphate (MAP). The MC-treated compound with 4% Mo showed significantly less leaching than the control without ball milling when co-compacted with both MAP and DAP. In a pot trial with simulated leaching, the uptake of Mo was greater for the MC-treated 4% Mo compound co-compacted into DAP than for the other Mo sources. Overall, our results indicate that MC-treated MoO3–ZnO could be used as a slow-release Mo source in high-rainfall areas. [ABSTRACT FROM AUTHOR]

Strong metal‐support interaction (SMSI) between transition metal nanoparticles and carbon matrix offers significant structure advantages due to the ability to modulate the electronic structure of metal nanoparticles, increase the density of active sites, and improve the conductivity of catalysts. Here, ultrafine nanoparticles of metallic molybdenum compounds (MoP, Mo2C, and MoS2) strongly coupled with mesoporous carbon CMK‐5 are synthesized. The confinement growth of nanoparticles in the pores of CMK‐5 produces encapsulated nanoparticles, affording facilitated electron transfer, and enhancing the HER activity induced by the SMSI effect. The hierarchical nanostructure and strong electronic interactions between the carbon substrate and molybdenum‐based nanoparticles allow efficient mass/electron transport between the carbon substrate and molybdenum‐based nanoparticles, improving the catalytic hydrogen evolution reaction (HER) activity. The effective electron exchange between the Mo species and the CMK‐5 support is studied by X‐ray photoelectron spectroscopy (XPS) measurement, confirming the presence of the SMSI effect. The resulting MoP/CMK‐5 catalyst exhibits outstanding HER performance in alkaline (65 mV@10 mA cm−2), acidic (123 mV@10 mA cm−2), and simulated seawater electrolytes (103 mV@10 mA cm−2), making it one of the most promising catalysts reported for HER. This work provides guidance on designing high‐performance electrocatalysts with SMSI for the enhancement of the electrochemical reaction. [ABSTRACT FROM AUTHOR]

Monochromatic Cr Kα radiation (5414.8 eV) was used to acquire high-energy photoelectron spectroscopy (HAXPES) data on pure Mo and bulk MoSe2 compound with special attention paid to binding energy scale correction and quantification. The reported spectra include a survey scan and high-resolution Mo 2s, Mo 2p1/2, Mo 2p3/2, Mo 3d, Mo 3p1/2, Mo 3p3/2, Mo 3s, Mo 4s, Mo4p, Se2s, Se 2p1/2, Se 2p3/2, Se 3s, Se 3p1/2, Se 3p3/2, and Se 3d core-levels. The data will be useful as reference core-level spectra for HAXPES studies on molybdenum and its compounds. [ABSTRACT FROM AUTHOR]

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]

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]

[Display omitted] Epoxides are important bulk chemicals, playing irreplaceable role in the chemical industry, but facing serious pollution and low productivity in the production process. Therefore, the development of green and efficient epoxidation of olefins by stable catalysts with low prices is of great significance. In this study, a Mo-MATP catalyst was prepared by modifying Mo(CO)₆ on attapulgite through Si-O bonding. Mo-MATP exhibits excellent performance (99% yield of cyclooctane oxide, CYCO) and stability (80% selectivity of CYCO after 17 cycles), highly tert -butyl hydroperoxide (TBHP) utilization, and extensive substrate scalability. Furthermore, the in-situ Fourier Transform Infrared Spectroscopy (FT-IR), Electron Spin-resonance Spectroscopy (ESR) and High Resolution Mass Spectrometry (HRMS) spectra suggest that TBHP would be activated by Mo-MATP to generate peroxyl radicals, which then oxidize alkenes to their corresponding epoxides. In this study, the stable loading of Mo would largely solve the problem of Mo loss during the catalytic process, thus providing a stable and dispersed Mo active center, enabling the catalyst to possess high catalytic performance and recycling stability. [ABSTRACT FROM AUTHOR]

Hydrogen is a clean and renewable energy source that is often regarded as a powerful alternative to traditional fossil fuels. The hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) are the critical stage in this technique, and an effective catalyst must be used to limit its significant overpotential. This report delves into the evaluation of MoO 3 /rGO-1000 as a cutting-edge electrocatalyst for green hydrogen production. The MoO 3 /rGO-1000 demonstrated exceptional HER stability and activity for 14 h, exhibiting an overpotential of 35 mV at a current density of 10 mAcm−2. Furthermore, the MoO 3 /rGO-1000, showed excellent OER activity having a lower overpotential of 213 mV at 10 mAcm−2. The enhanced results may be due to the synergistic effects, and by its inherent metallic conductivity and capacity to adsorb oxygen-containing molecules with high efficiency, MoO 3 offers an abundance of active sites for water oxidation throughout the OER process. In the interim, rGO functions as a highly effective electron conductor, improving overall electrocatalytic activity by facilitating charge transfer. Thus, this study concludes that the introduction of MoO 3 into graphene oxide significantly enhances the catalytic activities for hydrogen production. [Display omitted] • The fabrication of MoO 3 -rGO-1000 as a progressive material for hydrogen production. • The MoO 3 -rGO-1000 need lower overpotential of 35 mV for HER. • The MoO 3 /rGO-1000 shows superior OER activity with overpotential of 213 mV at 10 mAcm−2. • The MoO 3 -rGO-1000 show varied mechanisms with MoO 3 active sites for HER & OER. [ABSTRACT FROM AUTHOR]

Thiosulfonates and disulfides are important scaffolds in bioactive molecules and drugs, yet methods for the synthesis of these compounds that start from simple and commercially available feedstocks with sustainable routes are scarce. In this report, we present a green protocol for the synthesis of these valuable S-S motifs through selective oxidation of thiols using H2O2 or air as oxidant and anionic polyoxomolybdate (Mo8O26 4-) as catalyst. Notable features of this method are scalability, operational simplicity, broad functional-group compatibility, and good chemoselectivity. Mechanistic studies, such as radical trapping experiments, kinetic experiments, cyclic voltammetry, ultraviolet-visible spectroscopy, infrared spectroscopy and Raman spectral monitoring of the reaction mixture support formation of a molybdenum(V)-hydroxo-species and a molybdenum (VI)-peroxo-species to drive the two different catalytic cycles, respectively. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogenation of nitrate to ammonia using renewable electricity is a promising route for sustainability but lacks catalysts that can deliver balanced selectivity, activity, and durability. Here, a new family of noble metal‐free and high‐performing Chevrel phase Ni2Mo6T8 (T = S, Se, and Te) catalysts that have similar structural and textural properties and differ presumably only in chalcogenide anion is systematically studied. The side‐by‐side comparisons allow the uncovering of the critical roles of chalcogenide anions in impacting kinetic activities and long‐term durability. The incorporation of anions with larger size and smaller electronegativity from sulfide to selenide and telluride invokes stronger inhibition of the otherwise competing hydrogen evolution reaction (HER) and steers the hydrogenation toward the selective formation of ammonia, thus improving both Faradic selectivity and the turnover frequency to high levels of 99.4% and 21.5 s−1, respectively, on the Ni2Mo6Te8 catalyst. More significantly, the bulkier anion in the Ni2Mo6T8 catalyst kinetically inhibited the intercalation of electrolyte cations, a major degradation mechanism in the catalyst family examined here and delivered several times improved durability. Therefore, this study introduces novel active motifs for selective nitrate reduction and provides insights into the catalyst degradation mechanism and practical ways to improve durability. [ABSTRACT FROM AUTHOR]

A series of Molybdenum-containing dendritic mesoporous silica nanosphere (Mo-DMSN) catalysts were prepared by a one-step synthesis method and used as highly efficient catalysts for the transesterification of propylene glycol monomethyl ether (PM) and methyl acetate (MA) to propylene glycol methyl ether acetate (PMA). The nMo-DMSN catalysts were characterized by XRD, SEM, XPS, FT-IR, N2 adsorption–desorption and NH3-TPD. The results of FT-IR and XPS confirmed that Mo species enter into the framework of DMSN. Compared with those of the DMSN catalyst, the pore diameters and the acid density of the catalysts increased after the introduction of Mo. According to the results of NH3-TPD, the nMo-DMSN had both weak and medium acid sites, and the acid density increased with the increase of Mo content. The catalytic performance of these catalysts increases in the order of 0.075Mo-DMSN≈0.053Mo-DMSN≈0.036Mo-DMSN > 0.017Mo-DMSN > DMSN, which is consistent with the acid density of the catalysts. The 0.036Mo-DMSN catalyst still had excellent catalytic activity after 5 cycles. Therefore, the Mo-DMSN had significant activity and stability in the transesterification of PMA. [ABSTRACT FROM AUTHOR]

The discovery of the 'two birds, one stone' electrochemical nitrate reduction reaction (NO3RR) allows for the removal of harmful NO3− pollutants as well as the production of economically beneficial ammonia (NH3). However, current understanding of the catalytic mechanism of NO3RR is not enough, and this research is still challenging. To determine the mechanism needed to create efficient electrocatalysts, we thoroughly examined the catalytic activity of molybdenum-based diatomic catalysts (DACs) anchored on two-dimensional carbon-rich conjugated frameworks (2D CCFs) for NO3RR. Among the 23 candidate materials, after a four-step screening method and detailed mechanism studies, we discovered that NO3RR can efficiently generate NH3 by following the N-end pathway on the MoTi-Pc, MoMn-Pc, and MoNb-Pc, with limiting potential of −0.33 V, −0.13 V, and −0.38 V, respectively. The activity of NO3RR can be attributed to the synergistic effect of the TM1–TM2 dimer d orbital coupling to the anti-bonding orbital of NO3−. Additionally, high hybridization between the Mo-4d, TM-3d(4d), and NO3−−2p orbitals on the MoTMs-Pc DACs can speed up the flow of electrons from the Mo-TM dual-site to NO3−. The research presented here paves the way for the reasonable design of effective NO3RR catalysts and offers a theoretical basis for experimental research. [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]

The study aims to produce thermosetting resin from synthesized molybdenum‐modified high‐ortho thermoplastic phenolic resin through an addition reaction. Then, molybdenum‐modified high‐ortho thermosetting phenolic resin is blended with polyvinyl butyral and undergoes wet spinning to prepare as‐spun fibers and obtain high‐ortho molybdenum phenolic fibers via solution curing, microwave curing, or heat curing. Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis, scanning electron microscopy, and fiber strength testing were used to investigate the structure and properties of molybdenum‐modified high‐ortho phenolic fibers. Results showed that adding molybdic acid introduced Mo−O bonds into the molecular chain of high‐ortho phenolic resin, thereby improving the degree of cross‐linking and thermal stability. The residual carbon content of the fibers after heat treatment exceeded 60%, and the elongation at break and the breaking strength of the microwave‐cured fibers reached 4.2% and 155 MPa, respectively, and the mechanical properties were relatively good. The study of high‐ortho phenolic fibers aims to improve their properties and expand their applications through resin modifications. It provides a possible fiber preparation strategy for improving heat‐resistant phenolic fibers, thereby guiding the research of modified high‐ortho phenolic fibers. [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]

Platinum (Pt) inclusion on fibrous silica molybdenum (FSMO) and MoO 3 /KCC-1 catalysts has been prepared and utilized for the lower temperature (200–350 °C) catalytic isomerization of n-heptane. The impact of Pt inclusion towards the structure, morphology, and acid distribution of catalysts was characterized by XRD, FTIR, N 2 -physisorption, Py-IR, and H 2 -IR. Compared with MoO 3 /KCC-1, FSMO demonstrated superior MoO 3 dispersion and amount of Lewis acid site associated with the in-situ synthesis technique. Although Pt inclusion slightly lessened acid sites due to inevitable partial coverage by the Pt cluster, the considerably higher amount of Lewis acid sites compared to Brønsted and conjugated sufficiently for generating protonic acid sites for enriching the isomerization activity. In contrast to Pt/MoO 3 /KCC-1 and undoped catalysts, Pt/FSMO achieved a superior conversion of 70.9% with 63.6% isomer yield at a low temperature of 250 °C. The 28-h stability tests demonstrated that Pt/FSMO recorded stable isomerization activity, with a superior isomer yield (∼48–52%) and inferior cracking yield (<3.0%) than Pt/MoO 3 /KCC-1. [Display omitted] • FSMO, MoO 3 /KCC-1, Pt/FSMO, and Pt/MoO 3 /KCC-1 was synthesized for C 7 isomerization. • Mo insertion in Si-matrix induced Si-O-Mo formation, intensifying Lewis acid sites. • Pt inclusion promoted H 2 dissociation and enriched the amount of Lewis acid sites. • The highest i -C 7 yield of about 63.6% was attained for Pt/FSMO at 250 °C. • Excellent stability with low cracking revealed by Pt/FSMO compared to Pt/MoO 3 /KCC-1. [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 series of molybdenum(VI) complexes with aryl-functionalized alkyl dihydrazones was prepared by the reaction of [MoO2(acac)2] and the appropriate dihydrazone in methanol. Their solid-state structures were elucidated via single-crystal X-ray diffraction (SC-XRD) and Fourier-transform infra-red (FTIR) spectroscopy, while the thermal stability of compounds was inspected by combined thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments. The behaviour of complexes in DMSO-d6 solution was explored by nuclear magnetic resonance (NMR). The relevant data show that all complexes are dinuclear, with dihydrazones acting as ditopic hexadentate ligands. The in vitro cytotoxic activity of the prepared molybdenum(VI) complexes was evaluated on THP-1 and HepG2 cell lines, while their antibacterial activity was tested against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Moraxella catarrhalis bacteria. The majority of compounds proved to be non-cytotoxic, while some exhibited superior antibacterial activity in comparison to dihydrazone ligands. [ABSTRACT FROM AUTHOR]

The selective oxidation of saturated C–H bonds to carbonyl compounds under mild conditions can be of high economic value. Therefore, it is of great significance to develop an efficient catalyst for activating C–H bonds. Here, a new [P4MoV6O31]12−-based manganese complex (Hbiz)10{[Mn1.5(μ2-O)2(H2O)2][Mn(H2O)3]{Mn[Mo6O12(OH)3(H2PO4)(HPO4)3]2}}2·4H2O (biz = benzimidazole) was designed and synthesized under solvothermal conditions. Single crystal X-ray diffraction studies show that complex 1 is a three-dimensional supramolecular structure constructed from [Mn1.5(μ2-O)2(H2O)2][Mn(H2O)3]{Mn[Mo6O12(OH)3(H2PO4)(HPO4)3]2} double chains with trinuclear manganese clusters and protonated Hbiz. As a heterogeneous catalyst, it can efficiently catalyze the selective oxidation of diphenylmethane, the conversion rate can reach 95.1% within 24 hours, and the selectivity >99%, which is higher than those of most catalysts. The mechanism study shows that the oxidation reaction involves the interaction between the molybdenum center and the manganese center in complex 1 as well as the metal–metal charge transfer (MMCT) between the trinuclear manganese clusters. [ABSTRACT FROM AUTHOR]

This work is based on a comparative study of the weldments fabricated by Activated Flux Tungsten Inert Gas (A-TIG) welding and autogenous Tungsten Inert Gas (TIG) welding of 10 mm thick Inconel 617 plates. Flux powders used for A-TIG welding were Titanium dioxide (TiO2) and Silicon dioxide (SiO2). Macrostructure and microstructure analyses and characterization of mechanical properties of both A-TIG and TIG weldments were investigated. The microstructure of Inconel 617 was made up of several secondary phases and fine austenitic grains. Mechanical testing carried out in this study included Bend Test, Tensile Test, Vicker's Micro-Hardness Test and Charpy Impact Test at room temperature (RT) and a sub-zero temperature (SZT) of −50 ∘ C. The Bend test was found satisfactory for both A-TIG and TIG weldments. TIG weldments' tensile strength and microhardness were determined to be 782 MPa and 265.44 HV, respectively. However, it was determined that the base metal had a tensile strength of 756 MPa and that the tensile strength and microhardness of the A-TIG weldment were 707 MPa and 252.73 HV, respectively. The TIG weldment was proved to have the highest tensile strength and microhardness due to the availability of strengthening elements like Molybdenum (Mo) and Chromium (Cr), as carbides in the fusion zone. Impact toughness of the A-TIG weldment was higher than that of the TIG weldment both at room and sub-zero temperatures due to the application of TiO2 as flux and the high heat input during A-TIG welding. The ductile mode of fracture was observed in all weldments. [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]

Molybdenum coordination compounds, [MoO2L1(CH3OH)] (1) and [MoO2L2(CH3OH)]0.5(CH3OH) (2), were obtained by the reaction of molybdenum trioxide with ONO-donor ligands [H2L1 = (E)-4-amino-N'-(5-bromo-2-hydroxybenzylidene)benzohydrazide and H2L2 = (E)-4-amino-N'-(2-hydroxynaphthalen-1-yl)methylene)benzohydrazide]. The structures of 1 and 2 were determined by single crystal X-ray analysis and they further characterized by elemental analysis (carbon, hydrogen and nitrogen) and spectroscopic methods such as FT-IR, UV–Vis and NMR analyses. According to the structural analyses, a free amine functionality (Ph-NH2) was present in the structure of compounds 1 and 2. Therefore, compounds 1 and 2 were supported on the surface of functionalized silica gel by amidification reaction. The obtained supported catalysts (Si-Mo-1 and Si-Mo-2) were characterized by XPS, XRD, EDX, DRS, TGA and FT-IR analyses. The obtained supported catalysts (Si-Mo-1 and Si-Mo-2) were tested in the epoxidation of olefins using aqueous TBHP oxidant. Some effective parameters on the selectivity and activity of Si-Mo-1 and Si-Mo-2 like the effect of the concentration of catalyst and oxidant, temperature and solvent were studied. The supported catalysts were easily recovered from the mixture of the reaction by filtration and the recovered catalysts were also characterized by various analyses. The results indicated that the supported catalysts (Si-Mo-1 and Si-Mo-2) are selective and effective catalysts for epoxidation of olefins. [ABSTRACT FROM AUTHOR]

Guanidinium-containing oligomers, a poorly studied class of organic compounds, have attracted attention due to their bactericidal properties. A guanidinium-containing oligomer based on an aliphatic oligoepoxide is a newly synthesized substance with bactericidal activity, which gives it the prospects for use as a microbial corrosion inhibitor. Aim. The goal of the study was to synthesize oligomeric alkyl substituted guanidinium bromide and study of its anticorrosive properties in the presence of steel under the influence of corrosive active sulfate-reducing bacteria. Methods. The guanidine-containing alkyl substituted oligomer was obtained by the reaction of the aliphatic oligoepoxide DEG-1 with guanidine, followed by interaction with alkyl bromide. The anticorrosive properties of the guanidine-containing oligomer were studied using collection strains of sulfate-reducing bacteria: UCM B-11503 Desulfovibrio sp.10, UCM B-11501 Desulfovibrio desulfuricans DSM642, and UCM B-11502 Desulfovibrio vulgaris DSM644. The sulfate-reducing bacteria were grown on Postgate B medium for 14 days at a temperature of 28 ± 2 °C. The number of bacteria was determined by the method of tenfold dilution. The corrosion rate was determined by the gravimetric method. The physicochemical parameters of pH and redox potential of the bacterial culture liquid were studied by the potentiometric method. The accumulation of hydrogen sulfide in the culture liquid was determined by the iodometric method. Lipolytic activity was studied spectrophotometrically using a KFK-3 device by reaction with p-nitrophenyl palmitate, catalase activity -- using 0.03% hydrogen peroxide, which formed a stable colored complex with a 4% molybdenum diphosphate solution. The specific activity of the studied enzymes was expressed as unit ⋅ mg-1 protein. Protein was determined in the supernatant by the conventional Lowry method. Results. It was shown that the oligomer based on aliphatic oligoepoxide has biocidal properties. A significant inhibition of the development of sulfate-reducing bacteria (SRB) was observed after the oligomer was added; only dozens of bacterial cells were detected in the medium after the exposure period. The corrosion rate of steel in the presence of SBR without addition of inhibitors was 0.15-0.35 mg/cm² ⋅ h. The addition of DPC (a quaternary ammonium compound based on N-decylpyridinium chloride) (Kyiv Polytechnic Institute (KPI), Ukraine) to the culture medium led to a decrease in the steel corrosion rate to 0.032-0.047 mg ⋅ cm-2 h-1 (by 6.5-10.6 times). In the presence of Armohib CI-28 inhibitor (based on Diamine Ethoxylate) (Akzonobel. Holland), the corrosion rate was reduced to 0.02-0.039 mg ⋅ cm-2 h-1 (by 4.2-12.7 times). The addition of guanidinium-containing oligomer to the medium with bacteria reduced the corrosion rate to 0.075-0.079 mg/cm² ⋅ h (by 2.5-2.7 times). According to the mass loss of steel samples, the degree of metal protection against microbial corrosion in the presence of guanidinium-containing oligomer was 60.15-63.17%. Conclusions. The obtained data indicate that the guanidinium-containing oligomer based on aliphatic oligoepoxy has biocidal and anticorrosive properties and is promising for use as a means of combating microbially induced corrosion. [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]

This study reports the synthesis and characterization of new molybdenum compounds bearing benz[e]indenyl and benz[f]indenyl ligands. The capability of the ligands to undergo η5-to-η3 haptotropic rearrangement was evidenced on reactions with tris(pyrazolyl)methane. Appearance of the η3-coordination mode was determined by NMR spectroscopy and X-ray structure analysis on a single crystal. [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]

The subject of the research is features of synthesis of alumina cements on the basis of compositions of system CaO – CoO – Al2O3 – MoO3 with use of cobalt‐molybdenum‐containing waste for reception of refractory materials with a complex of the set properties. The processes of phase formation in raw mixtures have been investigated. X‐ray phase studies of clinkers fired at different temperatures and holding times proved that as a result of the interaction of the raw materials of the mixture in the material synthesizes a mixture of hydraulically active calcium mono‐ and di‐aluminate and refractory cobalt spinel, which provides the resulting complex high strength, accelerated curing time, fire resistance. The absence of phases corresponding to molybdenum compounds is explained by the fact that they are part of hydraulically active aluminates as limited solid solutions, deforming the crystal lattice and increasing hydraulic activity. Thus, it was found that the high strength of cement is due to the presence of calcium hydroaluminates such as C2AH8, aluminum hydroxide, as well as unhydrated grains of calcium aluminates, which will contribute to further long‐term strength. It is this coexistence of phases in both the crystalline and colloidal states provide high strength cement stone. [ABSTRACT FROM AUTHOR]

Molybdenum tailings powder (MTs) has potential pozzolanic activity and can be used as a mineral admixture. In order to comprehend the influence of MTs powder on the cement hydration process, the hydration heat and kinetics of composite cementitious materials (CCMs) were investigated using an isothermal calorimeter and the Krstulovic–Dabic model. Furthermore, the influences of fly ash (FA), slag (SL), and MTs powder on hydration heat were compared and analyzed, considering the same content. The results show that the proper amount of MTs can promote the hydration of CCMs. When the content of MTs is 5% and 15%, the second exothermic peak of the CCMs appears 2.30% and 4.27% earlier, and the exothermic peak increases by 2.72% and 1.34%, respectively. The cumulative heat release of CCMs gradually decreases with an increasing content of MTs powder. When the replacement of MTs, FA, and SL is 15%, respectively, the second exothermic peak of CCMs increases by 1.34%, −16.13%, and −12.04% for MTs, FA, and SL, respectively. The final heat release of MTs is higher than that of FA, but lower than that of SL. The hydration process of CCMs undergoes three stages: nucleation and crystal growth (NG), interactions at phase boundaries (I), and diffusion (D). [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]

Electrochemical activation is an effective method for synthesizing economically feasible heterogeneous hydrogen evolution reaction (HER) electrocatalysts. Herein, we first synthesized MoO2-Co2Mo3O8 precatalyst, which was electrochemically activated to produce K2Mo3O10 within the original phase to form the heterogeneous structure. The electrochemically activated samples demonstrate exceptional HER activity in alkaline medium, which exhibit a low overpotential of 31 mV at current density of 10 mA cm−2 (135 mV at 100 mA cm−2), as well as a small Tafel slope of 34 mV dec−1. This is due to the creation of multiphase heterostructures that prompt interfacial interactions and accelerate charge transfer. Simultaneously, the creation of additional active sites increases their intrinsic activities. The combined effects collectively enhance the HER performance. The application of this method in the preparation of HER catalysts is still relatively unexplored, thus rendering our work a pioneering contribution to the field. [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]

Synergistic optimization of nitrogen dissociation and hydrogen transfer might be an efficient strategy to develop a highly efficient ammonia synthesis catalyst. Herein, the Ni‐modified molybdenum nitride is used as the catalyst of ammonia synthesis. The presence of the highly dispersed Ni metal results in enhancement of nitrogen vacancy, causing the acceleration of the exchange and reaction of the lattice N species with the nitrogen species from the gaseous phase. In addition, the presence of Ni species facilitates the hydrogen transfer and spillover, as well as easy hydrogen release. As a result, the optimized molybdenum nitride catalyst with 0.1 wt% Ni shows a 2.5‐times higher catalytic activity than that of the catalyst without Ni species at 400°C owing to the coupling of nitrogen activation and hydrogen transfer effects. This general approach could inspire the rational design of other metal catalysts for ammonia synthesis. [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]

Formic acid is considered as a promising hydrogen storage material in the context of a green hydrogen economy. In this work, we present a series of aminophosphino and imidazolylamino Mo3S4 cuboidal clusters which are active and selective for formic acid dehydrogenation (FAD). Best results are obtained with the new [Mo3S4Cl3(ediprp)3](BPh4) (4(BPh4)) (ediprp=(2‐(diisopropylphosphino)ethylamine)) cluster, which is prepared through a simple ligand exchange process from the Mo3S4Cl4(PPh3)3(H2O)2 precursor. Under the conditions investigated, complex 4+ showed significantly improved performance (TOF=4048 h−1 and 3743 h−1 at 120 °C in propylene carbonate using N,N‐dimethyloctylamine as base after 10 min and 15 min, respectively) compared to the other reported molybdenum compounds. Mechanistic investigations based on stoichiometric and catalytic experiments show that cluster 4+ reacts with formic acid in the presence of a base to form formate substituted species [Mo3S4Cl3‐x(OCOH)x(ediprp)3]+ (x=1–3) from which the catalytic cycle starts. Subsequently, formate decarboxylation of the partially substituted [Mo3S4Cl3‐x(OCOH)x(ediprp)3]+ (x=1, 2, 3) catalyst through a β‐hydride transfer to the metal generates the trinuclear Mo3S4 cluster hydride. Dehydrogenation takes place through protonation by HCOOH to form Mo−H⋅⋅⋅HCOOH dihydrogen adducts, with regeneration of the Mo3S4 formate cluster. This proposal has been validated by DFT calculations. [ABSTRACT FROM AUTHOR]

Dimolybdenum complexes bearing 3,3′′′-(1,1′:3′,1′′:3′′,1′′′-quaterphenylene)-bridged pyridine-based PNP-type pincer ligand are designed and prepared according to DFT calculations on the cleavage step of dinitrogen-bridged dimolybdenum complexes bearing polyphenylene-bridged pyridine-based PNP-type pincer ligands. The dimolybdenum complexes are found to work as effective catalysts toward ammonia formation from dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions. [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]

Recently, hydrogen (H2) energy has attracted attention among eco-friendly energy sources because H2 energy is eco-friendly, energy-efficient, and abundant in nature. However, when the concentration of H2 in the atmosphere is more than 4%, H2 has a risk of explosion. H2 is a colorless, tasteless, and odorless gas that is difficult to detect with human senses. Therefore, developing an optimized hydrogen sensor is essential. Palladium (Pd) has good reactivity to hydrogen. Molybdenum disulfide (MoS2) has high carrier mobility, sensitive reactivity to toxic gases, and high surface-area-to-volume ratio. Therefore, we proposed hydrogen sensors that use Pd and MoS2. The main fabrication processes include MoS2 deposition through CVD and Pd deposition through DC sputtering. In this study, we utilized Pd and MoS2 to enable sensing at room temperature. By optimizing the Pd to a nanoparticle structure with an expansive surface area of 4 nm, we achieved a fast response time of 4–5 s and an enhanced yield through a simplified structure. Hydrogen sensors inherently exhibit sensitivity to various environmental factors. To address these challenges, technologies such as machine learning can be incorporated. Emphasizing low-power consumption and various application compatibilities becomes pivotal to promoting commercialization across diverse industries. [ABSTRACT FROM AUTHOR]

Development of the cost‐effective catalysts with excellent catalytic performance is highly demanded for ammonia synthesis, and the strong adsorption of ammonia greatly hinders the design of cost‐effective and high‐performance ammonia synthesis catalysts. Herein, we report that the addition of a small amount of Co species (0.1 wt%) into Mo2C catalyst, which can provide electrons to Mo2C, not only leads to improvement of the adsorption and migration of hydrogen, but also facilitates the adsorption and desorption of ammonia. Consequently, Mo2C catalyst with 0.1 wt%Co offers a 40% higher ammonia synthesis activity and a lower negative reaction order with respect to NH3 in comparison to Mo2C. This work stresses the importance of the minor components in improving the ammonia synthesis activity by accelerating the migration of reactants over the catalyst surface and the escape of products from the catalyst. [ABSTRACT FROM AUTHOR]

The relationships of the two-step regeneration of the slurry-phase hydroconversion catalyst separated as a component of a solid powder from the vacuum residue after distillation of the product obtained by hydroconversion of a mixture of petroleum tar and polymer waste were studied. The low-temperature oxidation of Mo sulfides was studied as the first step. High degree of oxidation of Mo sulfides to oxygen compounds of molybdenum in the highest oxidation state was reached at 250–400°С depending on the heat treatment time (from 30 to 150 min). The efficient oxidation is confirmed by the degree of transfer of the Mo oxides into an ammonia solution in the second step, leaching of the oxidation products obtained in the first step. The low-temperature oxidation of the catalyst concentrate as a component of the toluene-insoluble residue from the hydroconversion of a mixture of petroleum tar and polymer waste allows virtually complete (>95%) recovery of molybdenum compounds by leaching with 10% aqueous ammonia. [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 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]

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]

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]

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]