Decay kinetics of sensitive bioinorganic species in a SuperFocus mixer at ambient conditions

Schurr, D.; Strassl, Florian; Liebhäuser, Patricia; Rinke, Günter; Dittmeyer, Roland; Herres‐Pawlis, Sonja

doi:10.1039/c6re00119j

Cited by 25 publications

(32 citation statements)

References 29 publications

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“…With rate constants of 0.03 s –1 at 243 K and 0.11 s –1 at 253 K for complex O1 , it becomes clear that the rate of decay increases by a factor of more than three at a temperature difference of only 10 K. The Cu 2 O 2 intermediate O3 decays about 20 % faster than O1 . If compared to the decay of the Cu 2 O 2 species of complex [Cu(btmgp)I] with a rate of 0.01 s –1 at a temperature of 253 K, the complexes presented here show a 10 times higher reaction rate . The comparison concludes that Cu 2 O 2 complexes with aromatic bis(guanidine) ligands are less stable.…”

Section: Resultsmentioning

confidence: 69%

“…Bis(guanidine) ligands are particularly interesting because of their flexibility in the synthesis of different structures by combining guanidine units with different spacers . Bis(tetramethylguanidino)propane (btmgp) is a basic bis(guanidine) ligand, which has been studied in its structural parameters and oxygen activation abilities in many studies , . Most bis(guanidine)copper complexes form a bis(µ‐oxido) species, and some are active in oxidation catalysis , .…”

Section: Introductionmentioning

confidence: 99%

“…Most bis(guanidine)copper complexes form a bis(µ‐oxido) species, and some are active in oxidation catalysis , . To understand the mechanism and efficiency of the bis(guanidine)–oxido intermediate species, the formation and decay rates are evaluated with different spectroscopic methods, such as UV/Vis, stopped‐flow and fluorescence spectroscopy , . An extremely stabile Cu 2 O 2 species, based on a sterically highly demanding bis(guanidine) ligand system, was synthesised and analysed accordingly.…”

Section: Introductionmentioning

confidence: 99%

“…At temperatures above 233 K, bis(µ‐oxido) intermediates of the bis(guanidine) btmgp decay rapidly to the bis(µ‐hydroxido)dicopper(II) complex and a bis(µ‐alkoxido)(µ‐iodido)‐bridged dinuclear copper(II) complex in equal amounts . Investigations on the decay rates of the bis(guanidine)copper intermediates at low and ambient temperatures have been carried out earlier , , …”

Section: Introductionmentioning

confidence: 99%

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Oxygen Activation by Copper Complexes with an Aromatic Bis(guanidine) Ligand

et al. 2017

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Combining the new aromatic bis(guanidine) ligand bis(tetramethylguanidino)toluene (TMG2tol) and different copper salts led to four new complexes. The molecular structures were analysed by X‐ray diffraction. Three of the complexes are active in biomimetic activation of oxygen. It is the first time a bis‐µ‐oxido species of an aromatic guanidine copper complex is analysed by Raman and UV/Vis spectroscopy. The formation and decay of the bis(µ‐oxido)dicopper species were investigated at low temperatures up to 273 K by UV/Vis spectroscopy with a stopped‐flow setup. The results showed that the Cu2O2 intermediate of an aromatic guanidine–copper complex decays much faster than most known bis(guanidine) complexes. Moreover, natural bond orbital (NBO) analyses revealed that the aromatic guanidine is the stronger donor compared to the aliphatic one.

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Section: Resultsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxygen Activation by Copper Complexes with an Aromatic Bis(guanidine) Ligand

et al. 2017

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“…The reaction speed can be adjusted by choice of ligand and temperature. In this case, with the btmgp ligand at room temperature, the typical time of reaction is 4 s . In NMR, the transition of copper(I) to copper(II) is clearly visible by a change of relaxation parameters.…”

Section: Resultsmentioning

confidence: 99%

Imaging of copper oxygenation reactions in a bubble flow

Benders

Strassl

Fenger

et al. 2018

Magnetic Reson in Chemistry

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Reactions of gases with liquids play a crucial role in the production of many bulk chemicals. Often, the gas is bubbled into the chosen reactor. Most of the processes at the gas-liquid interface of the bubbles and in their tails are not fully understood and warrant further investigation. For this purpose, NMR imaging or Magnetic Resonance Imaging has been applied to visualize some of the processes in the bubble tail. To generate sufficient contrast, a magnetogenic gas-liquid reaction associated with a change of magnetic state, from diamagnetic to paramagnetic, was employed. In this work, a copper(I)-based compound was oxidized to copper(II) to exploit relaxation contrast. To match the speed of the rising bubbles to the acquisition time of the spin-echo imaging sequence, polyethylene glycol was added to increase the viscosity of the reacting solution. Images of the oxygen ingress into a static solution as well as of oxygen bubbles rising in the solution are presented. In both cases, changes in magnetism were observed, which reported the hydrodynamic processes.

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Influence of Bubble Bouncing on Mass Transfer and Chemical Reaction

2016

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The hydrodynamics of bubbly flows is dominated by bubble-induced turbulence and bubble-bubble interactions. Both phenomena influence the gas-liquid mass transfer as well as the mixing of reactants. If the time scales of mass transfer and mixing are in the same order as the time scales of a parallel-consecutive reaction, the yield and selectivity will be affected by the local hydrodynamics. An experimental setup is presented that enables the investigation of mass transfer during well-defined and adjustable bubble collisions. The influence of CO 2 bubble collisions on mass transfer is measured and modeled with a modified Sherwood number correlation. Further visualization of the concentration field in the vicinity of O 2 bubbles by means of laser-induced fluorescence demonstrates the dependency of mass transfer from a chemical reaction and permits the development of a first model approach.

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Decay kinetics of sensitive bioinorganic species in a SuperFocus mixer at ambient conditions

Abstract: For the first time the formation and decay of the thermally very sensitive bis(μ-oxo)dicopper species was monitored at ambient temperature in a continuous flow setup and the rate constant of the decay was measured.

Cited by 25 publications

References 29 publications

Oxygen Activation by Copper Complexes with an Aromatic Bis(guanidine) Ligand

Oxygen Activation by Copper Complexes with an Aromatic Bis(guanidine) Ligand

Imaging of copper oxygenation reactions in a bubble flow

Influence of Bubble Bouncing on Mass Transfer and Chemical Reaction

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