Hydrogen peroxide disproportionation with manganese macrocyclic complexes of cyclen and pyclen

Freire, David M.; Beeri, Debora; Pota, Kristof; Johnston, Hannah M.; Palacios, Philip M.; Pierce, Brad S.; Sherman, Benjamin D.; Green, Kayla N.

doi:10.1039/c9qi01509d

Cited by 12 publications

(23 citation statements)

References 52 publications

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“…In order to investigate the effect of the 15-pyN 3 O 2 Ph ligand on this reactivity, H 2 O 2 disproportionation reactions were carried out using a one-pot approach . The pH of the solution was selected based on the speciation curve; at pH 8, 95% of the Mn(II) ions are chelated by the ligand (Figure S19).…”

Section: Resultsmentioning

confidence: 99%

“…In order to investigate the effect of the 15-pyN 3 O 2 Ph ligand on this reactivity, H 2 O 2 disproportionation reactions were carried out using a one-pot approach. 58 The pH of the solution was selected based on the speciation curve; at pH 8, 95% of the Mn(II) ions are chelated by the ligand (Figure S19). An O 2 microsensor probe (Unisense, Denmark) inserted into a sealed pressure vessel, previously flushed with N 2 , was used to continuously measure the partial pressure of O 2 (P O 2 ) in mmHg every 0.2 s. Addition of H 2 O 2 resulted in oxygen evolution based on the formation of bubbles in the solution and a significant increase in P O 2 measured by the sensor.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study

et al. 2020

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Owing to the increasing importance of manganese(II) complexes in the field of magnetic resonance imaging (MRI), large efforts have been devoted to find an appropriate ligand for Mn(II) ion encapsulation by providing balance between the seemingly contradictory requirements (i.e., thermodynamic stability and kinetic inertness vs low ligand denticity enabling water molecule(s) to be coordinated in its metal center). Among these ligands, a large number of pyridine or pyridol based open-chain and macrocyclic chelators have been investigated so far. As a next step in the development of these chelators, 15-pyN3O2Ph and its transition metal complexes were synthesized and characterized using established methods. The 15-pyN3O2Ph ligand incorporates both pyridine and ortho-phenylene units to decrease ligand flexibility. The thermodynamic properties, protonation and stability constants, were determined using pH-potentiometry; the solid-state structures of two protonation states of the free ligand and its manganese complex were obtained by single crystal X-ray diffractometry. The results show a seven-coordinate metal center with two water molecules in the first coordination sphere. The longitudinal relaxivity of [Mn(15-pyN3O2Ph)]2+ was found to be 5.16 mM–1 s–1 at 0.49 T (298 K). Furthermore, the r 2p value of 11.72 mM–1 s–1 (0.49 T), which is doubled at 1.41 T field, suggests that design of this Mn(II) complex does achieve some characteristics required for contrast imaging. In addition, 17O NMR measurements were performed in order to access the microscopic parameters governing this key feature (e.g., water exchange rate). Finally, manganese complexes of ligands with analogous polyaza macrocyclic scaffold have been investigated as low molecular weight Mn(CAT) mimics. Here, we report the H2O2 disproportionation study of [Mn(15-pyN3O2Ph)]2+ to demonstrate the versatility of this ligand scaffold as well.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study

et al. 2020

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“…Similar to a Clark electrode, these are standalone systems and the sensor is fully contained in a narrow housing with only the probe ending, itself housed in a narrow glass pipet tip or a metal syringe tip, which needs to be in contact with the headspace or solution being measured. These sensors have been successfully used in several studies by the authors [ 49 , 101 ]. A second electrochemical method for measuring O 2 is a dual working electrode method (referred to as the collector-generator method) that functions in an analogous manner as a rotating ring-disc electrode but uses two static planar electrodes positioned in close proximity [ 102 ].…”

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confidence: 99%

Sustainable hydrogen production from water using tandem dye-sensitized photoelectrochemical cells

et al. 2021

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If generated from water using renewable energy, hydrogen could serve as a carbon-zero, environmentally benign fuel to meet the needs of modern society. Photoelectrochemical cells integrate the absorption and conversion of solar energy and chemical catalysis for the generation of high value products. Tandem photoelectrochemical devices have demonstrated impressive solar-to-hydrogen conversion efficiencies but have not become economically relevant due to high production cost. Dye-sensitized solar cells, those based on a monolayer of molecular dye adsorbed to a high surface area, optically transparent semiconductor electrode, offer a possible route to realizing tandem photochemical systems for H2 production by water photolysis with lower overall material and processing costs. This review addresses the design and materials important to the development of tandem dye-sensitized photoelectrochemical cells for solar H2 production and highlights current published reports detailing systems capable of spontaneous H2 formation from water using only dye-sensitized interfaces for light capture.

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“…Many methods have been employed in the treatment of wastewater, such as adsorption, biodegradation, ultrafiltration, and advanced oxidation processes (AOPs) . Among these methods, AOPs showed higher efficiency in comparison to the other methods, which exhibit an ability to generate strongly oxidizing hydroxyl radicals ( • OH), which can convert organic pollutants to smaller organic compounds or CO 2 and H 2 O . The Fenton reaction is one of the most cost-effective AOPs .…”

Section: Introductionmentioning

confidence: 99%

“…4 Among these methods, AOPs showed higher efficiency in comparison to the other methods, which exhibit an ability to generate strongly oxidizing hydroxyl radicals ( • OH), which can convert organic pollutants to smaller organic compounds or CO 2 and H 2 O. 5 The Fenton reaction is one of the most cost-effective AOPs. 6 H 2 O 2 in the solution can be activated by ferrous ions, affording highefficiency oxidability for the degradation of cyanides, 7 phenols, 8 organic dyes, 9 etc.…”

Section: ■ Introductionmentioning

confidence: 99%

Heterometal–Organic Cages as Photo-Fenton-like Catalysts

et al. 2021

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Metal–organic cages, a class of supramolecular containers constructed by the self-assembly of metal ions and organic ligands, show great promise as catalytic agents. In this work, we designed and synthesized a series of rhombic dodecahedral Ni–Cu heterometal imidazolate cages (Ni8Cu6L24) that can act as highly active photo-Fenton-like catalysts. These cages possess a high ability to generate hydroxyl radicals (•OH) under visible light in the presence of H2O2, which can rapidly degrade organic pollutants (e.g., rhodamine B, methylene blue, and methyl orange) into CO2 and H2O. Besides, they are robust catalysts, with high catalytic activity and reusability under conditions in high H2O2 concentration, providing potentially advanced materials for degrading persistent organic pollutants.

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Hydrogen peroxide disproportionation with manganese macrocyclic complexes of cyclen and pyclen

Abstract: Pyclen and cylen complexes of manganese show pH dependent catalase activity with improved TOF and TON for the more rigid pyclen derivative. Spectroscopic investigation shows O2 evolution corresponds with the presence of a μ-O bridged species.

Cited by 12 publications

References 52 publications

Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study

Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study

Sustainable hydrogen production from water using tandem dye-sensitized photoelectrochemical cells

Heterometal–Organic Cages as Photo-Fenton-like Catalysts

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