Electrocatalytic reduction of oxygen with phenanthroline-strapped porphyrins

2007 ◽  
Vol 11 (04) ◽  
pp. 212-221 ◽  
Author(s):  
Frédéric Melin ◽  
Corinne Boudon ◽  
Mamadou Lo ◽  
Kurt J. Schenk ◽  
Michel Bonin ◽  
...  
Keyword(s):  
Pyrolytic Graphite ◽  
Iron Complex ◽  
Electrocatalytic Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
Saturated Water ◽  
Electron Reduction ◽  
Disk Electrodes ◽  
Parent Ligand

The electrochemical behavior of three cytochrome c oxidase models has been investigated. All the models are derived from a phenanthroline-strapped, porphyrin framework that binds zinc(II) or iron(III) chloride in the porphyrin subunit, and copper(I) in the phenanthroline site. The iron complex and the bimetallic zinc(II) copper(I) complex of the parent ligand have been characterized by X-ray diffraction. One model consists of the parent structure on which C 12 alkyl chains have been added. This soluble model achieves electrochemical 2-electron reduction of oxygen in organic solvents without the addition of an exogenous axial base, and in the presence of an organic or inorganic source of protons. The two other models comprise the parent phenanthroline-strapped porphyrin framework, on which two pendant imidazoles have been incorporated. These models adsorbed on ring-disk electrodes with an edge-oriented, pyrolytic graphite (EOPG) disk and a platinum ring, efficiently catalyze the 4-electron reduction of oxygen in dioxygen saturated water at neutral pH.

scholarly journals Insertion of Phosphenium Ions into a Bicyclo[1.1.0]Tetraphosphabutane Iron Complex

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3920
Author(s):  
Martin Weber ◽  
Gábor Balázs ◽  
Alexander V. Virovets ◽  
Eugenia Peresypkina ◽  
Manfred Scheer
Keyword(s):  
Diffraction Analysis ◽  
Room Temperature ◽  
31P Nmr ◽  
Spectroscopic Studies ◽  
Iron Complex ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphenium Ions

By reacting [{Cp‴Fe(CO)2}2(µ,η1:1-P4)] (1) with in situ generated phosphenium ions [Ph2P][A] ([A]− = [OTf]− = [O3SCF3]−, [PF6]−), a mixture of two main products of the composition [{Cp‴Fe(CO)2}2(µ,η1:1-P5(C6H5)2)][PF6] (2a and 3a) could be identified by extensive 31P NMR spectroscopic studies at 193 K. Compound 3a was also characterized by X-ray diffraction analysis, showing the rarely observed bicyclo[2.1.0]pentaphosphapentane unit. At room temperature, the novel compound [{Cp‴Fe}(µ,η4:1-P5Ph2){Cp‴(CO)2Fe}][PF6] (4) is formed by decarbonylation. Reacting 1 with in situ generated diphenyl arsenium ions gives short-lived intermediates at 193 K which disproportionate at room temperature into tetraphenyldiarsine and [{Cp‴Fe(CO)2}4(µ4,η1:1:1:1-P8)][OTf]2 (5) containing a tetracyclo[3.3.0.02,7.03,6]octaphosphaoctane ligand.

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

Unusual X-Ray Diffraction Vector Shift Observed in Heterogeneous Langmuir-Blodgett Multilayer Films

1992 ◽  
Vol 247 ◽  
Author(s):  
Yoshio Nogami ◽  
Kazuyoshi Ogasawara ◽  
Shigeki Takeuchi ◽  
Takehiko Ishiguro ◽  
Kazumasa Ohsumi ◽  
...  
Keyword(s):  
Diffraction Method ◽  
X Ray Diffraction ◽  
Diffraction Vector ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Alkyl Chains ◽  
Oscillatory Structure ◽  
Langmuir Blodgett Films ◽  
Diffraction Patterns ◽  
Vector Shift

ABSTRACTStacking of heterogeneous Langmuir-Blodgett films was studied by high resolution X-ray diffraction method using synchrotron radiation (SR) source. The diffraction patterns of the heterogeneous films formed with alternately deposited Cd salts of fatty acids with different length of alkyl chains exhibit anomalous oscillatory structure in diffraction vector.

scholarly journals X-Ray Diffraction Studies on Alicyclic Saturated Discotic Liquid Crystals

1987 ◽  
Vol 42 (6) ◽  
pp. 631-635 ◽  
Author(s):  
H. W. Neuling ◽  
H. Stegemeyer ◽  
K. Praefcke ◽  
B. Kohne
Keyword(s):  
Liquid Crystalline ◽  
Optical Observations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
New Class ◽  
X Ray Scattering ◽  
Oriented Samples ◽  
Hexagonal Columnar

The discotic liquid crystalline phase of a new class of disc-like molecules (hexa-O-alkanoylscyllo- inositoles) is studied by small angle X-ray scattering, DSC and optical observations. Comparison of these three methods allows the determination of the structural arrangement. X-ray film exposures of oriented samples clearly demonstrate the hexagonal columnar ordered type of mesophases. A simple model calculation shows that the alkyl chains of neighbouring columns interpenetrate each other to a small extent.

Synthesis and Structures of μ3-Oxo-centered Mixed-valent Trinuclear Iron Complexes with 1-Methyl-imidazole Ligands

2007 ◽  
Vol 62 (9) ◽  
pp. 1117-1122 ◽  
Author(s):  
Ji-Xiang Dai ◽  
Fang-Hui Wu ◽  
Alexander Rothenberger ◽  
Qian-Feng Zhang
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Iron Complexes ◽  
Iron Complex ◽  
Methanol Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Analyses ◽  
Methyl Imidazole ◽  
Imidazole Ligands

Treatment of the μ3-oxo-centered mixed-valent trinuclear iron complex [Fe3(μ3-O)(μ-OAc)6- (H2O)3] (1) in methanol solution with one, two, or three equivalents of 1-methyl-imidazole (C4H6N2) afforded the substitution products [Fe3(μ3-O)(μ-OAc)6(H2O)2(C4H6N2)] (2), [Fe3(μ3-O)(μ-OAc)6- (H2O)(C4H6N2)2] (3), and [Fe3(μ3-O)(μ-OAc)6(C4H6N2)3] (4), respectively. Complexes 2 - 4 were characterized by spectroscopic and elemental analyses, and the crystal structures of complexes 3 · 1.5MeOH· 2H2O and 4 have been determined by single-crystal X-ray diffraction. The results indicate that in 2 - 4 the trinuclear core unit [Fe3(μ3-O)(μ-OAc)6] of 1 is preserved.

Iron complexes of tris(4-nitrophenyl)corrole, with emphasis on the (nitrosyl)iron complex

2012 ◽  
Vol 16 (05n06) ◽  
pp. 663-673 ◽  
Author(s):  
Pinky Singh ◽  
Irena Saltsman ◽  
Atif Mahammed ◽  
Israel Goldberg ◽  
Boris Tumanskii ◽  
...  
Keyword(s):  
Iron Complexes ◽  
Iron Complex ◽  
Oxidation Products ◽  
Spectroscopic Techniques ◽  
X Ray ◽  
Nitrosyl Iron Complex ◽  
Reduction And Oxidation ◽  
Electron Reduction ◽  
The One ◽  
Redox Centre

The iron complexes of 5,10,15-tris(4-nitrophenyl)corrole have been prepared and characterized by various spectroscopic techniques. The (nitrosyl)iron complex is diamagnetic and its X-ray structure reveals an almost perfectly linear Fe–N–O bond. EPR spectroscopy in conjunction with 15N labelling were used to deduce the redox centre of the one-electron reduction and oxidation products of the (nitrosyl)iron corrole.

An X-ray diffraction system with controlled relative humidity and temperature

1996 ◽  
Vol 11 (4) ◽  
pp. 288-289 ◽  
Author(s):  
H. Hashizume ◽  
S. Shimomura ◽  
H. Yamada ◽  
T. Fujita ◽  
H. Nakazawa ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Control Unit ◽  
Saturated Water Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturated Water ◽  
Sample Chamber ◽  
Diffraction Patterns ◽  
Xrd Patterns

A system enabling X-ray diffraction patterns under controlled conditions of relative humidity and temperature has been devised and combined with an X-ray powder diffractometer. Relative humidity in the sample space is controlled by mixing dry N2 gas with saturated water vapor. Temperatures of the sample and inner wall of the sample chamber are monitored by two attached thermocouples and the information was fed back to the control unit. Relative humidity between 0% and the 95%, and temperature between room temperature and 60 °C can be controlled. All parameters including those for XRD are programmable and the system runs automatically. The function of the system was checked by recording the XRD patterns of montmorillonite (a clay mineral) and NaCl under increasing and decreasing relative humidity.

Manganese(III) and manganese(IV) corroles: synthesis, spectroscopic, electrochemical and X-ray structural characterization

2005 ◽  
Vol 09 (06) ◽  
pp. 398-412 ◽  
Author(s):  
Zhongping Ou ◽  
Christoph Erben ◽  
Marie Autret ◽  
Stefan Will ◽  
Daniel Rosen ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Esr Spectroscopy ◽  
Spectroscopic Characterization ◽  
Axial Ligand ◽  
X Ray Diffraction ◽  
Nonaqueous Media ◽  
X Ray ◽  
Cation Radicals ◽  
Uv Visible ◽  
Electron Reduction

The synthesis, spectroscopic characterization and electrochemistry of four Mn(III) and Mn(IV) octaethylcorroles are reported and the potentials of the Mn(III) / Mn(IV) and Mn(IV) / Mn(III) processes examined as a function of the axial ligand. The investigated compounds are represented as ( OEC ) Mn , ( OEC ) MnCl , ( OEC ) Mn ( py ) and ( OEC ) Mn ( C 6 H 5) where OEC is the trianion of octaethylcorrole. The first one-electron oxidation of ( OEC ) Mn III and ( OEC ) Mn III ( py ) in PhCN or pyridine containing 0.1 M TBAP leads to the facile formation of a Mn(IV) species while the first one-electron reduction of ( OEC ) Mn IV Cl and ( OEC ) Mn IV ( C 6 H 5) in the same two solvents leads to the Mn(III) corrole. All other redox reactions occur at the corrole macrocycle to give π-cation radicals or π-anion radicals and there is no evidence for electrogeneration of a compound with a Mn(II) oxidation state as is the case for manganese(III) porphyrins which are all easily reduced to the Mn(II) state in nonaqueous media. The products of each Mn(III)/Mn(IV) redox reaction were characterized by UV-visible and/or ESR spectroscopy and the structures of ( OEC ) MnCl , ( OEC ) Mn ( py ) and ( OEC ) Mn ( C 6 H 5) were determined by single-crystal X-ray diffraction.

Dimerization of indenocorannulene radicals: imposing stability through increasing strain and curvature

2020 ◽  
Vol 7 (22) ◽  
pp. 3591-3598 ◽  
Author(s):  
Andrey Yu. Rogachev ◽  
Yikun Zhu ◽  
Zheng Zhou ◽  
Shuyang Liu ◽  
Zheng Wei ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Electron Reduction

One-electron reduction of bowl-shaped indenocorannulene affords a new stable dimeric dianion, as confirmed by single-crystal X-ray diffraction, NMR and UV-vis spectroscopy, and DFT calculations.

Sign in / Sign up

Export Citation Format

Share Document