scholarly journals Phenylvinylidene RePt Complexes Containing Diphenylphosphine Ligands at the Platinum Atom: Synthesis, IR, NMR Spectroscopic and Electrochemical Properties

2020 ◽  
pp. 385-394
Author(s):  
Oleg S. Chudin ◽  
Victor V. Verpekin ◽  
Galina V. Burmakina ◽  
Dmitry V. Zimonin ◽  
Alexander A. Kondrasenko ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Spectroscopic Data ◽  
Redox Reactions ◽  
Redox Properties ◽  
Molecular Structures ◽  
Platinum Atom ◽  
First Time

The μ-phenylvinylidene complexes Cp(CO)2RePt(μ-C=CHPh)(PPh2H)(L) [L = PPh3 (1), P(OPri)3 (2)] were synthesized for the first time. Their IR, NMR spectroscopic and redox properties were studied. Based on IR, NMR spectroscopic data their molecular structures were proposed. The pathways of redox-reactions of the complexes were determined

scholarly journals New Copper and Oxomolybdate Robson-Type Polynuclear Macrocyclic Complexes: Structure, Spectroscopy, and Electrochemical Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Marcelo Carpes Nunes ◽  
Marcos Antonio Ribeiro ◽  
Fábio Souza Nunes
Keyword(s):  
Electrochemical Properties ◽  
Macrocyclic Ligand ◽  
Metal Cations ◽  
Redox Properties ◽  
Macrocyclic Complexes ◽  
Molecular Structures ◽  
Polynuclear Complexes ◽  
Unique Mode ◽  
Macrocycle Ligand ◽  
Mode Of Coordination

The polynuclear complexes [Mo3O8(tidf)]·dmso·2H2O (1) and [{Cu2(tidf)}2(μ-Mo8O24)] (2) (tidf2−is a symmetrical tetraiminodiphenolate Robson-type macrocyclic ligand) were prepared from equimolar combinations of [Mg2(tidf)](NO3)2·4H2O, [MoO2Cl2(dmso)2] (for1) and complex1and Cu(ClO4)2·4H2O (for2) in acetonitrile. Molecular structures of both complexes were determined and showed atypical modes of coordination. A significant observation was the remarkable flexibility of the macrocycle ligand that effectively accommodated the steric demands of metal cations and the packing forces and showed a unique mode of coordination. Spectroscopic (UV-vis and FTIR) and redox properties are discussed.

Influence of Metal Core Composition on Redox Properties and Photoreactivity of the Clusters [H4-xRu4-xRhx(CO)12] (x = 0, 2, 3, 4)

2001 ◽  
Vol 66 (7) ◽  
pp. 1062-1077 ◽  
Author(s):  
Maarten J. Bakker ◽  
Tapani A. Pakkanen ◽  
František Hartl
Keyword(s):  
Electrochemical Properties ◽  
Electrochemical Reduction ◽  
Redox Properties ◽  
Metal Core ◽  
Loss Product ◽  
Condensation Reactions ◽  
Core Composition ◽  
Co Dissociation ◽  
Major Reduction

Electrochemical properties of tetrahedral clusters [H2Ru2Rh2(CO)12], [HRuRh3(CO)12] and [Rh4(CO)12] were investigated in order to evaluate the influence of metal core composition in the series [H4-xRu4-xRhx(CO)12] (x = 0-4). The cluster [H3Ru3Rh(CO)12] was not available in sufficient quantities. As reported for [H4Ru4(CO)12], electrochemical reduction of the hydride-containing clusters [H2Ru2Rh2(CO)12] and [HRuRh3(CO)12] also results in (stepwise) loss of hydrogen, producing the anions [HRu2Rh2(CO)12]-, [Ru2Rh2(CO)12]2- and [RuRh3(CO)12]-. These anions can also be prepared from the neutral parent clusters via chemical routes. Electrochemical reduction of [Rh4(CO)12] does not result in the formation of any stable tetranuclear anion. Instead, [Rh5(CO)15]- and [Rh6(CO)15]2- are the major reduction products detected in the course of IR spectroelectrochemical experiments. Most likely, these cluster species are formed from the secondary CO-loss product [Rh4(CO)11]2- by fast redox condensation reactions. Their reoxidation regenerates parent [Rh4(CO)12], together with some [Rh6(CO)16]. Unlike [H4Ru4(CO)12] that undergoes photochemical CO-dissociation, [H2Ru2Rh2(CO)12] and [Rh4(CO)12] are completely photostable in neat hexane and dichloromethane as well as in the presence of oct-1-ene.

scholarly journals The Three Pillars of Natural Product Dereplication. Alkaloids from the Bulbs of Urceolina peruviana (C. Presl) J.F. Macbr. as a Preliminary Test Case

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 637
Author(s):  
Mariacaterina Lianza ◽  
Ritchy Leroy ◽  
Carine Machado Rodrigues ◽  
Nicolas Borie ◽  
Charlotte Sayagh ◽  
...  
Keyword(s):  
Natural Product ◽  
Spectroscopic Data ◽  
Preliminary Test ◽  
Rapid Identification ◽  
Molecular Structures ◽  
Data Sources ◽  
Test Case ◽  
The Andes ◽  
Spectroscopic Signatures ◽  
Product Chemistry

The role and importance of the identification of natural products are discussed in the perspective of the study of secondary metabolites. The rapid identification of already reported compounds, or structural dereplication, is recognized as a key element in natural product chemistry. The biological taxonomy of metabolite producing organisms, the knowledge of metabolite molecular structures, and the availability of metabolite spectroscopic signatures are considered as the three pillars of structural dereplication. The role and the construction of databases is illustrated by references to the KNApSAcK, UNPD, CSEARCH, and COCONUT databases, and by the importance of calculated taxonomic and spectroscopic data as substitutes for missing or lost original ones. Two NMR-based tools, the PNMRNP database that derives from UNPD, and KnapsackSearch, a database generator that provides taxonomically focused libraries of compounds, are proposed to the community of natural product chemists. The study of the alkaloids from Urceolina peruviana, a plant from the Andes used in traditional medicine for antibacterial and anticancer actions, has given the opportunity to test different approaches to dereplication, favoring the use of publicly available data sources.

Isolation and Structure Determination of a Heat Shock Protein Inducer, Asparagus-Derived Proline-Containing 3-Alkyldiketopiperazines (Asparaprolines), From a Standardized Extract of Asparagus officinalis Stem

2020 ◽  
Vol 15 (3) ◽  
pp. 1934578X2091468
Author(s):  
Shoichiro Inoue ◽  
Jun Takanari ◽  
Keima Abe ◽  
Ayako Nagayama ◽  
Yukinobu Ikeya ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Spectroscopic Data ◽  
Asparagus Officinalis ◽  
Hsp70 Mrna ◽  
Mrna Induction ◽  
Natural Amino Acids ◽  
First Time ◽  
Hsp70 Induction

ETAS® has been developed from the stems of Asparagus officinalis L. as a functional ingredient for nutraceuticals. ETAS possesses heat shock protein 70 (HSP70) induction activity and may contribute to maintenance and improvement of health. Here, 3 compounds (1, 2, 3) were isolated from ETAS. The structures of 1, 2, and 3 were deduced by HREIMS and NMR spectroscopic data, and the compounds were identified as cyclo(l-Phe-l-Pro), cyclo(l-Tyr-l-Pro), and cyclo(l-Leu-l-Pro), respectively. Each compound contained a diketopiperazine ring derived from proline with an alkyl group at C-3; thus, we termed them asparagus-derived proline-containing 3-alkyldiketopiperazines (Asparaprolines). In an HSP70 mRNA induction assay in HL-60 cells, Asparaprolines significantly enhanced the expression of HSP70 mRNA compared with a control. To our knowledge, these results demonstrate for the first time that proline-containing diketopiperazines derived from natural amino acids exhibit HSP70 mRNA induction activity.

Antidiabetic and Antioxidant Activities of Major Flavonoids of Cynanchum acutum L. (Asclepiadaceae) Growing in Egypt

2008 ◽  
Vol 63 (9-10) ◽  
pp. 658-662 ◽  
Author(s):  
Ghada A. Fawzy ◽  
Hossam M. Abdallah ◽  
Mohamed S. A. Marzouk ◽  
Fathy M. Soliman ◽  
Amany A. Sleem
Keyword(s):  
Blood Glucose ◽  
Spectroscopic Data ◽  
Methanolic Extract ◽  
Antioxidant Activities ◽  
First Report ◽  
Insulin Levels ◽  
Butanol Fraction ◽  
Aerial Parts ◽  
First Time

Seven flavonoids were isolated from the butanol fraction of the methanolic extract of the aerial parts of Cynanchum acutum L. (Asclepiadaceae). All of which have been isolated for the first time from the genus Cynanchum. Their structures were established as quercetin 3-O-β-galacturonopyranoside (1), quercetin 7-O-β-glucopyranoside (2), tamarixtin 3-O-β-galacturonopyranoside (3), kaempferol 3-O-β-galacturonopyranoside (4), 8-hydroxyquercetin 3-O-β-galactopyranoside (5), tamarixtin 3-O-α-rhamnopyranoside (6), and tamarixtin 7-O-α-arabinopyranoside (7) on the basis of their chromatographic properties, chemical and spectroscopic data. The major isolated flavonoids 1, 2 and 3 were found to exhibit significant antioxidant and antidiabetic activities (by measuring blood glucose and insulin levels). This is the first report about the antioxidant and antidiabetic activities of compounds 1 - 3.

Synthesis, Characterization, Investigation of Capacitance and Redox Properties of Self-assembled Phe-Phe with Ferrocene Conjugates

2021 ◽  
Author(s):  
Om Shanker Tiwari
Keyword(s):  
Nucleic Acid ◽  
Electrochemical Properties ◽  
Self Assembly ◽  
Peptide Nucleic Acid ◽  
Redox Properties ◽  
Self Assembled ◽  
Acid Unit

The synthesis, nanostructure self-assembly and electrochemical properties of a series of ferrocene conjugated peptides derived from the dipeptide Phe-Phe, nucleoside and the peptide nucleic acid unit which are covalently attached...

Direct electrochemistry of nanoparticulate Fe2O3 in aqueous solution and adsorbed onto tin-doped indium oxide

2001 ◽  
Vol 73 (12) ◽  
pp. 1885-1894 ◽  
Author(s):  
Katy J. McKenzie ◽  
Frank Marken
Keyword(s):  
Indium Oxide ◽  
Redox Reactions ◽  
Direct Detection ◽  
Direct Electrochemistry ◽  
Redox Properties ◽  
Fe2o3 Nanoparticles ◽  
Solution Composition ◽  
Electrode Surfaces ◽  
Buffer Solutions ◽  
Electrochemical Processes

Nanoparticulate iron oxides occur naturally, for example, in soil, water, and in the cytoplasm of living cells. The redox properties and detection of these nanoparticles are therefore of considerable importance. Understanding and mimicking nanoparticle-based redox reactions may lead to new types of water-based electrochemical processes. In this study, the electrochemical detection of 4­5 nm diameter Fe2O3 nanoparticles dissolved in aqueous buffer solutions is investigated as a model system. Voltammetric experiments with nanoparticulate Fe2O3 are reported based on two complementary approaches: (i) Fe2O3 nanoparticles adsorbed onto tin-doped indium oxide (ITO) electrodes are shown to give well-defined voltammetric reduction responses and (ii) hydrodynamic voltammety in the presence of fast (24 kHz ultrasound-enhanced) mass transport is shown to allow the direct detection of Fe2O3 nanoparticles in solution. Both the adhesion and the electrochemical reactivity of Fe2O3 nanoparticles at ITO electrode surfaces are strongly affected by the solution composition and the pH.

scholarly journals Computational Spectroscopy of the Cr–Cr Bond in Coordination Complexes

2021 ◽  
Author(s):  
Toru Shiozaki ◽  
Bess Vlaisavljevich
Keyword(s):  
Spectroscopic Data ◽  
Technological Development ◽  
Vibrational Analysis ◽  
Bond Distance ◽  
Coordination Complexes ◽  
Vibrational Structure ◽  
Complete Active Space ◽  
Computational Spectroscopy ◽  
First Time ◽  
Good Agreement

We report the accurate computational vibrational analysis of the Cr–Cr bond in dichromium complexes using second-order multireference complete active space methods (CASPT2), allowing direct comparison with experimental spectroscopic data both to facilitate interpreting the low-energy region of the spectra and to provide insights into the nature of the bonds themselves. Recent technological development by the authors has realized such computation for the first time. Accurate simulation of the vibrational structure of these compounds has been hampered by their notorious multiconfigurational electronic structure that yields bond distances that do not correlate with bond order. Some measured Cr–Cr vibrational stretching modes, ν(Cr2), have suggested weaker bonding, even for so-called ultrashort Cr–Cr bonds, while others are in line with the bond distance. Here we optimize the geometries and compute ν(Cr2) with CASPT2 for three well-characterized complexes, Cr2(O2CCH3)4(H2O)2, Cr2(mhp)4, and Cr2(dmp)4. We obtain CASPT2 harmonic ν(Cr2) modes in good agreement with experiment at 282 cm−1 for Cr2(mhp)4 and 353 cm−1 for Cr2(dmp)4, compute 50Cr and 54Cr isotope shifts, and demonstrate that the use of the so-called IPEA shift leads to improved Cr–Cr distances. Additionally, normal mode sampling was used to estimate anharmonicity along ν(Cr2) leading to an anharmonic mode of 272 cm−1 for Cr2(mhp)4 and 333 cm−1 for Cr2(dmp)4.

scholarly journals Negligible Voltage Hysteresis with Strong Anionic Redox in Conventional Battery Electrode

2020 ◽  
Author(s):  
Kehua Dai ◽  
Jing Mao ◽  
Zengqing Zhuo ◽  
Guo Ai ◽  
Wenfeng Mao ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Redox Reactions ◽  
Coulombic Efficiency ◽  
Redox Systems ◽  
Redox Mechanism ◽  
Practical Applications ◽  
Battery Electrode ◽  
Voltage Hysteresis ◽  
First Time ◽  
Initial Coulombic Efficiency

<div>Lattice oxygen redox reactions (ORR) offers opportunities for developing highcapacity batteries, however, suffers the notoriously high voltage hysteresis and low initial coulombic efficiency, which hinder its practical applications. Particularly, ORR was widely considered inherent to these kinetic issues. In this paper, unambiguous evidence of strong and reversible ORR is found in Na<sub>2/3</sub>Ni<sub>1/3</sub>Mn<sub>2/3</sub>O<sub>2</sub>, which displays negligible voltage hysteresis (0.1 V) and high initial coulombic efficiency with a highly stable electrochemical profile. Our independent and quantitative analysis of all the Ni, Mn and O states consistently interpret the redox mechanism of Na<sub>2/3</sub>Ni<sub>1/3</sub>Mn<sub>2/3</sub>O<sub>2</sub>, which reveals, for the first time, a conventional 3d transition-metal ORR system with facile kinetics and highly stable electrochemical profile that previously found only in cationic redox systems.</div>

scholarly journals Crystal structure of two N′-(1-phenylbenzylidene)-2-(thiophen-3-yl)acetohydrazides

2019 ◽  
Vol 75 (8) ◽  
pp. 1090-1095
Author(s):  
Trung Vu Quoc ◽  
Linh Nguyen Ngoc ◽  
Duong Tran Thi Thuy ◽  
Manh Vu Quoc ◽  
Thien Vuong Nguyen ◽  
...  
Keyword(s):  
Torsion Angle ◽  
Phenyl Ring ◽  
Spectroscopic Data ◽  
Crystal Packing ◽  
Thiophene Ring ◽  
Hirshfeld Surface ◽  
Molecular Structures ◽  
Dihedral Angles ◽  
Crystal And Molecular Structures ◽  
Phenyl Rings

The synthesis, spectroscopic data, crystal and molecular structures of two N′-(1-phenylbenzylidene)-2-(thiophen-3-yl)acetohydrazides, namely N′-[1-(4-hydroxyphenyl)benzylidene]-2-(thiophen-3-yl)acetohydrazide, C13H10N2O2S, (3a), and N′-[1-(4-methoxyphenyl)benzylidene]-2-(thiophen-3-yl)acetohydrazide, C14H14N2O2S, (3b), are described. Both compounds differ in the substituent at the para position of the phenyl ring: –OH for (3a) and –OCH3 for (3b). In (3a), the thiophene ring is disordered over two orientations with occupancies of 0.762 (3) and 0.238 (3). The configuration about the C=N bond is E. The thiophene and phenyl rings are inclined by 84.0 (3) and 87.0 (9)° for the major- and minor-occupancy disorder components in (3a), and by 85.89 (12)° in (3b). Although these dihedral angles are similar, the conformation of the linker between the two rings is different [the C—C—C—N torsion angle is −ac for (3a) and −sc for (3b), while the C6—C7—N9—N10 torsion angle is +ap for (3a) and −sp for (3b)]. A common feature in the crystal packing of (3a) and (3b) is the presence of N—H...O hydrogen bonds, resulting in the formation of chains of molecules running along the b-axis direction in the case of (3a), or inversion dimers for (3b). The most prominent contributions to the surface contacts are those in which H atoms are involved, as confirmed by an analysis of the Hirshfeld surface.

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