Properties Of Rhenium Research Articles

Photochemical properties of rhenium disulfide/graphene heterojunctions with different stacking structures

Energy and pollution are crucial problems. Photocatalysis technology is a way to solve the problem by electrolysis of aquatic hydrogen and degradation of organic pollutants. Preparing photocatalysts with fantastic photocatalytic activity and high photocarrier separation efficiency is a key technique. In recent years, two-dimensional (2D) nanomaterials have attracted much attention because of their unique structures and excellent properties, which are different from the traditional materials’. The 2D nanomaterials demonstrate in-plane covalent bonds and out-of-plane van der Waals interactions. Therefore, two 2D materials can form van der Waals heterojunctions by van der Waals forces, which are also known as nanocomposites. However, there is an interesting problem in the study of van der Waals heterojunctions in the field of photochemistry, which has not been paid attention to no studied. Specifically, that problem is whether the photochemical properties of the van der Waals heterojunctions are affected by the different stacking structures after the relationship between the upper and lower positions has been adjusted. In this paper, the van der Waals heterojunction films with different stacking structures ReS<sub>2</sub>-Gra (ReS<sub>2</sub> on the top) and Gra-ReS<sub>2</sub> (graphene on the top) are prepared by liquid phase exfoliation combined with electrophoretic deposition method. The heterojunctions are utilized as photoelectrodes in photochemical reactions, and the findings are as follows. i) Different stacking structures will affect the photoelectric chemical characteristics of heterojunctions: comparing with the ReS<sub>2</sub>-Gra photoelectrode, the photocurrent of the Gra-ReS<sub>2</sub> photoelectrode increased by 54% under the same conditions. We think that the main reason is due to the fact that graphene has a zero-band gap structure and holds a wider spectral absorption range. ii) The construction of the heterojunction significantly enhances the photochemical properties of the photoelectrode materials, resulting in a larger and rapidly photocurrent response. The photocurrent response of the Gra-ReS<sub>2</sub> photoelectrode (2.47 μA) is twice that of the pure ReS<sub>2</sub> photoelectrode (1.16 μA). Based on the experimental results of this paper, a possible mechanism for effective separation and prolonged recombination of the photo-induced electro-hole pairs in ReS<sub>2</sub>/graphene heterojunction is proposed. This work not only puts forward new ideas for preparing the van der Waals heterojunctions, but also lays a theoretical foundation for further studying the solar energy conversion devices.

Synthesis and properties of rhenium(I) bridged boron-dipyrromethene dyad

We synthesized the hexa-coordinated Re ( I ) bridged BODIPY dyad 1 in decent yield by thermal reaction of benzimidazole substituted BODIPY 2 with Re ( CO )5 Cl . The dyad 1 was characterized by 1 H , 13 C , 11 B , 19 F NMR, ESI-MS, FTIR, UV-vis, and electrochemical techniques. In Re ( I ) bridged dyad 1, the Re ( I ) ion is hexa-coordinated and coordinates with nitrogen atoms of two benzimidazole units, three axial carbonyl ligands and one chloride atom. The presence of three carbonyl groups in dyad 1 was verified by 13 C NMR and IR spectroscopy. The absorption and steady-state fluorescence spectra of Re ( I ) bridged BODIPY dyad showed a slightly broad and hypsochromically shifted absorption and emission bands compared to BODIPY 2. The electrochemical studies indicated that, the Re ( I ) bridge BODIPY dyad 1 was easy to reduce compared to BODIPY 2 supporting the electron deficient nature dyad upon Re ( I ) ion binding. The molecular structure of dyad 1 was further elucidated by DFT computational studies.

Synthesis, Characterization and Photophysical Properties of Rhenium(I) Complexe with 2-(naphthalen-2-yl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline

In this paper, a Re(I) complex [Re(CO)3(E2)Cl], where E2 = 2-(naphthalen-2-yl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline(E2), was synthesized and characterized by 1H NMR successfully. Experimental data confirm that Re(I) complex [Re(CO)3(E2)Cl] is high-energy-emitting one. The broad band emission upon excitation at λ = 400 nm with the emission maximum locates at λ = 581 nm in solid state and 614nm in CH2Cl2 solution were observed.

Syntheses and photoluminescence properties of rhenium(I) complexes based on dipyrido[3,2-a:2′,3′-c]phenazine derivatives with carbazole moiety

Four rhenium(I) complexes ReL1–ReL4 based on dipyrido[3,2-a:2′,3′-c]phenazine (L1) and derivatives L2-L4 ligands (L2: 10,13-dibromodipyrido[3,2-a:2′,3′-c]phenazine, L3: 10-bromo-13-carbazolyl-dipyrido[3,2-a:2′,3′-c]phenazine, L4: 10,13-dicarbazolyldipyrido[3,2-a:2′,3′-c]phenazine) were synthesized and characterized. The Re(I) complexes ReL1–ReL4 show photoluminescent emissions at 556, 582, 637 and 662 nm, respectively, assigned to d (Re)→ ∗ (diimine) MLCT phosphorescence in CH2Cl2 solution. The carbazole containing complexes ReL3 and ReL4, as compared to ReL1, exhibit higher luminescence. These observations imply that modification of diimine rhenium(I) carbonyl complexes with carbazole moiety would lead to efficient phosphorescent properties.

Molybdenite as a Rhenium Carrier: First Results of a Spectroscopic Approach Using Synchrotron Radiation

The chemical and physical properties of rhenium render it a highly demanded metal for advanced applications in important industrial fields. This very scarce element occurs mainly in ores of porphyry copper-molybdenum deposits associated with the mineral molybdenite, MoS2, but it has also been found in granite pegmatites and quartz veins as well as in volcanic gases. Molybdenite is a typical polytype mineral which crystal structure is based on the stacking of [S-Mo-S] with molybdenum in prismatic coordination by sulphide anions; however, it is not yet clearly established if rhenium ions replace Mo4+ cations in a disordered way or else, if such replacement gives rise to dispersed nanodomains of a rhenium-rich phase. As a contribution to clarify this question, an X-ray absorption spectroscopy (XANES) study using synchrotron radiation was performed at the Re L3-edge of rhenium-containing molybdenite samples. Obtained results are described and discussed supporting the generally accepted structural perspective that rhenium is mainly carried by molybdenite through the isomorphous replacement of Mo, rather than by the formation of dispersed Re-specific nanophase(s).

Syntheses, characterization and properties of rhenium(I) tricarbonyl complexes based on tetrathiafulvalene substituted naphthyridine ligands

Abstract New amide functional tetrathiafulvalene ligands containing naphthyridine moiety (L1–L3) were synthesized. Further coordination reactions of these ligands with Re(CO)5Cl afford three interesting rhenium tricarbonyl complexes, ClRe(CO)3(L). Crystal structures of ClRe(CO)3(L1) (1) and ClRe(CO)3(L2) (2) have been determined. Electrochemical and spectroscopic properties of all compounds are investigated.

Synthesis, Characterization and Photophysical Properties of Rhenium(I) Complexes Containing 4,5-Diazafluorene Ligan

Two related tricarbonyl rhenium complexes with the formula of [Re(CO)3(L)Cl], where L=4,5-diazafluoren-9-one (Dafo-Re) and 9-(phenylamino)-4,5-diazafluoren (PADF-Re) were successfully synthesized with the aim to explore the effect of the geometry of Dafo on Rhenium(I) coordination, and characterized by 1H NMR. Photophysical behaviors are investigated by UV–vis absorption and Fluorescence spectra. The two complexes Dafo-Re and PADF-Re show metal-to-ligand charge transfer absorptions at ca.391nm, ca.394 nm and emissions at ca.492nm, ca.470nm, respectively.

Syntheses, Characterization, and Properties of Rhenium(I) Tricarbonyl Complexes with Tetrathiafulvalene-Fused Phenanthroline Ligands

A series of tetrathiafulvalene-annulated phenanthroline ligands, 4′,5′-dimethyldithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L1), 4′,5′-ethylenedithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L2), and 4′,5′-bis(methyloxycarbonyl)dithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L3), have been prepared by a facile and efficient synthetic procedure under mild conditions. Further coordination reactions of these ligands with Re(CO)5Cl afford new rhenium tricarbonyl complexes, Re(CO)3Cl(L) (L = L1, 3a; L = L2, 3b; L = L3, 3c), respectively. X-ray crystal structure determinations on 3a,c reveal that the ligands are nearly planar and they show a unique packing mode in the solid state. The electrochemical and spectroscopic behavior of these compounds (L1−L3, 3a−c) has been studied. The results suggest that the redox-active tetrathiafulvalene-phenanthroline ligands are useful for new metal complexes.

The effect of neutron irradiation on mechanical properties of rhenium

Abstract Polycrystalline and single crystal rhenium tensile specimens have been neutron irradiated at 50°C to fluences up to 2.6 × 1019 n/cm2 and subsequently tested in tension. The microstructure of the single crystals was examined by transmission electron microscopy. The yield strengths of the polycrystalline specimens increased from 19,000 psi in the unirradiated material to 143,000 psi after a fluence of 2.6 × 1019 n/cm2. Slip was observed on the basal and prismatic planes and (1121) twinning was found to be the main twinning mode in the single crystals. The single crystal yield strengths also increased markedly with fluence and were found to increase at a greater rate in those crystals oriented for prismatic slip. The radiation damage greatly retarded twin growth at the higher fluences but did not appear to affect twin nucleation. Channeling of dislocation through the small defect clusters occurred in the irradiated specimens. Deformation twinning did not result in channeling type behavior although a...

Rhenium Recovery By Solvent Extraction and Electrodeposition

A procedure developed by the US Bureau of Mines to recover rhenium in the form of electrolytic flakes by electrowinning the metal from a solvent-extraction strip solution is described. The recovered rhenium contains only about 0.1 % Mo and spectrograph traces of other impurities, such as copper, aluminum, calcium, chromium, iron, platinum, and silicon. The uses and properties of rhenium are discussed, and conventional recovery methods are reviewed.

Work-Hardening and Ductility of Rhenium and their Relation to the Behaviours of Other Metals having a Hexagonal Structure

POLYCRYSTALLINE rhenium work-hardens rapidly when tested in tension at room temperature (the proportional limit is 26,000 p.s.i. and the ultimate tensile strength is 164,000 p.s.i.1), and has an elongation of 24 per cent. The fracture is intergranular2. In the present communication an extension of the study of the mechanical properties of rhenium to single crystals is reported. The behaviour of rhenium is then compared with other metals having a hexagonal structure.

Catalytic properties of rhenium. Communication 1. Rhenium as a dehydrogenation catalyst

1. Rhenium, deposited on charcoal, is an active catalyst for cyclohexane dehydrogenation. It is found that the nature of the carrier considerably affects the activity of rhenium catalysts. 2. Over rhenium deposited on charcoal, n-heptane is dehydrocyclized and cumene is dehydrogenated to α-methylstyrene.