scholarly journals Promotion and Tuning of the Electrochemical Reduction of Hetero- and Homobimetallic Zinc Complexes

2021 ◽  
Author(s):  
Shaun Kelsey ◽  
Amit Kumar ◽  
Allen G. Oliver ◽  
Victor W. Day ◽  
James Blakemore
Keyword(s):  
Metal Ions ◽  
Lewis Acids ◽  
Xrd Analysis ◽  
Bimetallic Complexes ◽  
Prior Work ◽  
X Ray Diffraction ◽  
Redox Active ◽  
Reorganization Energies ◽  
Potential Shifts ◽  
Cyclic Voltammetry Data

Compounds containing multiple metals attract significant interest due to the useful redox and reactivity properties of such species. Here, the electrochemical properties of a family of macrocyclic complexes that feature a zinc(II) center paired with a second redox-inactive metal cation in heterobimetallic (Na+, Ca2+, Nd3+, Y3+) motifs or a homobimetallic (Zn2+) motif have been investigated. The new complexes were prepared via a divergent strategy, isolated, and structurally characterized by single-crystal X-ray diffraction (XRD) analysis. XRD results show that the structure of the complexes is modulated by the identity of the incorporated secondary metal ions. Cyclic voltammetry data reveal that ligand-centered reduction is promoted in the bimetallic complexes and that the paired metal ions synergistically influence the redox properties of the complexes. Similar to prior work from our group and others, the bimetallic complexes containing stronger Lewis acids undergo more significant reduction potential shifts; contrasting with prior work on complexes containing redox-active metals, however, the zinc(II) complexes studied here display faster electron transfer (as judged by lower reorganization energies, λ) when incorporating di- or tri-valent Lewis acids in contrast to monovalent (and more weakly acidic) sodium. The quantified trends in these data offer insights that help distinguish metal- versus ligand-centered reduction of bimetallic complexes.<br>

scholarly journals Promotion and Tuning of the Electrochemical Reduction of Hetero- and Homobimetallic Zinc Complexes

2021 ◽  
Author(s):  
Shaun Kelsey ◽  
Amit Kumar ◽  
Allen G. Oliver ◽  
Victor W. Day ◽  
James Blakemore
Keyword(s):  
Metal Ions ◽  
Lewis Acids ◽  
Xrd Analysis ◽  
Bimetallic Complexes ◽  
Prior Work ◽  
X Ray Diffraction ◽  
Redox Active ◽  
Reorganization Energies ◽  
Potential Shifts ◽  
Cyclic Voltammetry Data

Compounds containing multiple metals attract significant interest due to the useful redox and reactivity properties of such species. Here, the electrochemical properties of a family of macrocyclic complexes that feature a zinc(II) center paired with a second redox-inactive metal cation in heterobimetallic (Na+, Ca2+, Nd3+, Y3+) motifs or a homobimetallic (Zn2+) motif have been investigated. The new complexes were prepared via a divergent strategy, isolated, and structurally characterized by single-crystal X-ray diffraction (XRD) analysis. XRD results show that the structure of the complexes is modulated by the identity of the incorporated secondary metal ions. Cyclic voltammetry data reveal that ligand-centered reduction is promoted in the bimetallic complexes and that the paired metal ions synergistically influence the redox properties of the complexes. Similar to prior work from our group and others, the bimetallic complexes containing stronger Lewis acids undergo more significant reduction potential shifts; contrasting with prior work on complexes containing redox-active metals, however, the zinc(II) complexes studied here display faster electron transfer (as judged by lower reorganization energies, λ) when incorporating di- or tri-valent Lewis acids in contrast to monovalent (and more weakly acidic) sodium. The quantified trends in these data offer insights that help distinguish metal- versus ligand-centered reduction of bimetallic complexes.<br>

scholarly journals Revealing the Influence of Secondary Metals on Redox-Active Palladium Complexes

2022 ◽  
Author(s):  
Riddhi Golwankar ◽  
Amit Kumar ◽  
Victor Day ◽  
James Blakemore
Keyword(s):  
Electron Transfer ◽  
Metal Ions ◽  
Lewis Acids ◽  
Reorganization Energy ◽  
Palladium Complexes ◽  
Lewis Acidity ◽  
X Ray Diffraction ◽  
Isolation And Characterization ◽  
Redox Active ◽  
Energy Penalty

Incorporation of redox-inactive metals into redox-active complexes and catalysts attracts attention for engendering new reactivity modes, but this strategy has not been extensively investigated beyond the first-row of the transition metals. Here, the isolation and characterization of the first series of heterobimetallic complexes of palladium with mono-, di-, and tri-valent redox-inactive metal ions are reported. A Reinhoudt-type heteroditopic ligand with a salen-derived [N2,O2] binding site for Pd and a crown-ether-derived [O6] site has been used to prepare isolable adducts of the Lewis acidic redox-inactive metal ions (Mn+). Comprehensive data from single-crystal X-ray diffraction analysis reveal distinctive trends in the structural properties of the heterobimetallic species, including an uncommon dependence of the Pd•••M distance on Lewis acidity. The reorganization energy associated with reduction of the heterobimetallic species is strongly modulated by Lewis acidity, with the slowest heterogeneous electron transfer kinetics associated with the strongest incorporated Lewis acids. This hitherto unexplored reorganization energy penalty for electron transfer contrasts with prior thermodynamic studies, revealing that kinetic parameters should be considered in studies of reactivity involving heterobimetallic species.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

A study on using expanded perlite with hydroxyapatite: Reinforced bio-composites

2021 ◽  
pp. 095441192199656
Author(s):  
Erdoğan Karip ◽  
Mehtap Muratoğlu
Keyword(s):  
Body Fluid ◽  
Xrd Analysis ◽  
Cold Isostatic Pressing ◽  
Expanded Perlite ◽  
X Ray Diffraction ◽  
Pressing Method ◽  
X Ray ◽  
Infra Red ◽  
Ft Ir

People are exposed to different kinds of diseases or various accidents in life. Hydroxyapatite (HA) has been widely employed for bone treatment applications. In this study, HA was extracted from sheep bones. Bio-composites were doped with 1, 5, and 10 wt.% of expanded perlite and 5 wt.% of ZrO2–MgO-P2O5. The bio-composites were prepared by the cold isostatic pressing method (250 MPa) and sintered at 900°C for 1 h. In order to evaluate the characteristics of the bio-composites, microhardness, density, X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analyses were carried out on them. Additionally, the specimens whose characteristics were determined were kept in synthetic body fluid (SBF), and their in vitro behavior was examined. As a result, it was observed that microhardness increased as both the weight and the grain size of the expanded perlite were increased. Calcium silicate, tri-calcium phosphate, and hydroxyapatite were observed in the XRD analysis of all samples, and the formation of apatite structures was increased by addition of ZrO2–MgO–P2O5.

scholarly journals Anodic Stripping Voltammetry with the Hanging Mercury Drop Electrode for Trace Metal Detection in Soil Samples

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 107
Author(s):  
Kequan Xu ◽  
Clara Pérez-Ràfols ◽  
Amine Marchoud ◽  
María Cuartero ◽  
Gastón A. Crespo
Keyword(s):  
Metal Ions ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Redox Active ◽  
Active Metal ◽  
Metal Detection ◽  
Trace Metal Detection

The widely spread use of the hanging mercury drop electrode (HMDE) for multi-ion analysis is primarily ascribed to the following reasons: (i) excellent reproducibility owing to the easy renewal of the electrode surface avoiding any hysteresis effect (i.e., a new identical drop is generated for each measurement to be accomplished); (ii) a wide cathodic potential window originating from the passive hydrogen evolution and solvent electrolysis; (iii) the ability to form amalgams with many redox-active metal ions; and (iv) the achievement of (sub)nanomolar limits of detection. On the other hand, the main controversy of the HMDE usage is the high toxicity level of mercury, which has motivated the scientific community to question whether the HMDE deserves to continue being used despite its unique capability for multi-metal detection. In this work, the simultaneous determination of Zn2+, Cd2+, Pb2+, and Cu2+ using the HMDE is investigated as a model system to evaluate the main features of the technique. The analytical benefits of the HMDE in terms of linear range of response, reproducibility, limit of detection, proximity to ideal redox behavior of metal ions and analysis time are herein demonstrated and compared to other electrodes proposed in the literature as less-toxic alternatives to the HMDE. The results have revealed that the HMDE is largely superior to other reported methods in several aspects and, moreover, it displays excellent accuracy when simultaneously analyzing Zn2+, Cd2+, Pb2+, and Cu2+ in such a complex matrix as digested soils. Yet, more efforts are required towards the definitive replacement of the HMDE in the electroanalysis field, despite the elegant approaches already reported in the literature.

Study on Adsorption of Crosslinked Starch Microspheres towards Heavy Metal Ions

2013 ◽  
Vol 834-836 ◽  
pp. 531-535
Author(s):  
Li Yan Yang ◽  
Yi Hui Guo ◽  
Li Li Yu ◽  
Jing You
Keyword(s):  
Metal Ions ◽  
Reversed Phase ◽  
Adsorption Rate ◽  
X Ray Diffraction ◽  
Adsorption Selectivity ◽  
X Ray ◽  
Starch Microsphere ◽  
Other Substances ◽  
Effects Of Media ◽  
Kinetics Of

A type of cross-linking starch microsphere (CSMs) has been synthesized via reversed phase suspension method. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The adsorption kinetics of Co (II) on the CSMs, selectivity of adsorption CSMs towards Co (II),Cu (II),Pb (II),Cd (II) and adsorption effects of media towards Co (II) were investigated. The CSMs and its adsorption product were comparatively characterized by X-ray diffraction (XRD). The results showed that The adsorption rate is mainly controlled by liquid film diffusion, and the constant of adsorption rate is 0.0686min-1 at 308K. The crystal structure of the CSMs decreased greatly after the incorporation of Co (II). Co (II) has better adsorption selectivity on CSMs. Ions coexist and other substances in the solution have certain impact on adsorption. Those data are helpful for treatment of the wastewater containing heavy ions.

scholarly journals An Insight into Chemistry and Structure of Colloidal 2D-WS2 Nanoflakes: Combined XPS and XRD Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1969
Author(s):  
Riccardo Scarfiello ◽  
Elisabetta Mazzotta ◽  
Davide Altamura ◽  
Concetta Nobile ◽  
Rosanna Mastria ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Xrd Analysis ◽  
Crystal Habit ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Evaluation ◽  
Rational Understanding ◽  
Structural Inspection

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T’ and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples.

scholarly journals Effect of Molybdenum Content on the Corrosion and Microstructure of Low-Ni, Co-Free Maraging Steels

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 852
Author(s):  
Asiful H. Seikh ◽  
Hossam Halfa ◽  
Mahmoud S. Soliman
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Alloying Element ◽  
X Ray ◽  
Maraging Steels ◽  
Eds Analysis ◽  
Electroslag Refining

Molybdenum (Mo) is an important alloying element in maraging steels. In this study, we altered the Mo concentration during the production of four cobalt-free maraging steels using an electroslag refining process. The microstructure of the four forged maraging steels was evaluated to examine phase contents by optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Additionally, we assessed the corrosion resistance of the newly developed alloys in 3.5% NaCl solution and 1 M H2SO4 solution through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Furthermore, we performed SEM and energy-dispersive spectroscopy (EDS) analysis after corrosion to assess changes in microstructure and Raman spectroscopy to identify the presence of phases on the electrode surface. The microstructural analysis shows that the formation of retained austenite increases with increasing Mo concentrations. It is found from corrosion study that increasing Mo concentration up to 4.6% increased the corrosion resistance of the steel. However, further increase in Mo concentration reduces the corrosion resistance.

Sign in / Sign up

Export Citation Format

Share Document