Synthetic oxygen carriers related to biological systems

Jones, Robert; Summerville, David A.; Basolo, Fred

doi:10.1021/cr60318a002

Cited by 1,060 publications

(532 citation statements)

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“…State Mn1-C may be assigned to an Mn(III)1(O2) complex, but such a species has been reported to be thermally very unstable in solution. [32][33][34][35] STM measurements indicated that Mn1-C was generally stable for at least an hour. Furthermore, inspection of many STM images indicated that the molecules of Mn1-C were distributed non-randomly over the surface.…”

mentioning

confidence: 99%

“…An overview of the possible reaction pathways involving manganese porphyrins and oxygen, based on the literature [1][2][3]18,[20][21][22][23][24][25][26][27][28][29] and the observations described here, is depicted in Figure 1. A reduction of the manganese centre of the porphyrin from Mn(III) to Mn(II) with loss of the counterion 20 is a requirement for the binding of an oxygen molecule to give a dioxygen adduct 21 .…”

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Detection of different oxidation states of individual manganese porphyrins during their reaction with oxygen at a solid/liquid interface

et al. 2013

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[4][5][6][7] . The majority of these studies use ensemble techniques in solution, such as electrochemistry and absorption, electron paramagnetic resonance and nuclear magnetic resonance spectroscopy. The scanning tunneling microscope (STM) has proven to be a promising tool to study reactions at the molecular level [8][9][10][11][12] , and initial experiments have been reported in which the reactive properties of metal porphyrins were studied on a surface at the single molecule level by STM in ultrahigh vacuum (UHV) [13][14][15][16][17] and under ambient conditions 18,19 .Here we report detailed STM studies of the complex redox chemistry of reactions between 10,15,R,R,porphyrin manganese(III) chloride (Mn1Cl, Fig. 2a) and different oxygen donors at a solid/liquid interface. Although the dynamic nature of the molecules at this interface complicates the use of techniques that are typically being used under UHV conditions, such as X-ray 3 Photoelectron Spectroscopy (XPS), STM can provide extremely high spatial resolution and insight into changes in the electronic properties of molecules with a liquid medium over them.These liquid conditions make the system far more comparable with processes taking place in biological systems than the UHV conditions, where solvent-mediated factors such as the diffusion and concentration of reactants are fully absent. It is in principle possible with STM to monitor single molecules at the highest detail while they are involved in multistep chemical reactions with STM, and to image and identify reactants, intermediates and products in the most direct way, i.e. by imaging. This approach allows the study of reaction dynamics in realspace and real-time, which may provide unique information about reaction mechanisms that remains hidden in ensemble measurements at the macroscopic scale. STM may reveal variations in reactivity of single molecules, the relation of these variations to molecular adsorption geometry, and cooperativity effects at the nanometre scale.An overview of the possible reaction pathways involving manganese porphyrins and oxygen, based on the literature 1-3,18,20-29 and the observations described here, is depicted in Figure 1 In a first experiment we deposited a droplet of a ~10 −5 M solution of Mn1Cl in 1-octanoic acid at the basal plane of a freshly cleaved highly oriented pyrolytic graphite (HOPG) sample under ambient conditions. Related alkyl-functionalised free base porphyrin molecules are known to form well-ordered monolayers on the same substrate 30,31 . STM revealed the 5 instantaneous self-assembly of the molecules of Mn1Cl in extended lamellar arrays, in which the porphyrin planes are adsorbed parallel to the surface and the alkyl chains interdigitated (Fig. 2B). The orientation of the lamellae and the alkyl chains with respect to the main crystallographic directions of the graphite surface is identical to that observed for the corresponding free base derivative. 30 When the surface was scanned under ambient conditions at a negative bias voltage of −800 mV and ...

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Detection of different oxidation states of individual manganese porphyrins during their reaction with oxygen at a solid/liquid interface

et al. 2013

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“…were shifted to lower wavelength in the Co(II)-HST system with respect to the [Co(H 2 O) 6 ] 2+ complex, suggesting an increase in the ligand field strength 66 . In the region of pH ≈ 2, out of our range of potentiometric measurements, the predominant specie would be the [Co(H 2 O) 6 ] 2+ complex, so, it is not any complex between HST and Co(II) at this pH. However, at pH ≈ 4 and pH ≈ 8, where, in agreement with potentiometric measurements, the ML and M(OH)L (where L represents ST -) are, respectively, the predominant species, the wavelength of the absorption maxima were shifted at very similar λ, suggesting that the coordination sphere might be similar in both cases and different from the [Co(H 2 O) 6 4 ], which was measured in the 400-900 nm range 65 , suggests an octahedral geometry around the metal ion 66 …”

Section: Electronic Spectramentioning

confidence: 99%

“…7.67 (6) a Sulfathiazole, HST, is designed by HL. Co(II) is designed by M. The numbers in parentheses are the estimated errors in the last significant figure.…”

Section: Structural Data and Topological Analysismentioning

confidence: 99%

“…The main aims, which have a great academic and practical interest in general, were to improve knowledge of the coordination chemistry of soft and hard metal ions in solvents of different donating properties, to study how basicity and steric effects may affect the selectivity pattern in metal coordination [1][2][3][4][5] and the binding, transport and activation of small molecules such as dioxygen, carbon monoxide, carbon dioxide, nitric oxide and sulfur dioxide. This purpose is very important in chemical, biochemical, biological, environmental and industrial fields [6][7][8] . For example, Co(II) and other metal complexes play an important role in the industrial cleaning of gaseous effluents from power plants through the suggested simultaneous absorption of nitric oxide and sulfur dioxide [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

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The interaction between sulfathiazole and cobalt(II): potentiometric studies

Bellú¹,

Rizzotto²,

Okulik³

et al. 2007

Quím. Nova

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Recebido em 19/6/06; aceito em 17/11/06; publicado na web em 2/7/07Potentiometric studies of sulfathiazole (HST) in the presence and absence of cobalt(II) were performed. Equilibrium constants for the formation of the detected species, [Co(ST)] + and [Co(ST)(OH)], are reported. UV-Vis spectrophotometric measurements suggest that the coordination Co(II)-sulfathiazole might be through a N atom, which, in agreement with MO calculations, could be a thiazolic one. In spite of sulfonamides being better ligands at pH >7, [Co(ST)] + was found at pH ≈ 3.

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