Oxidation mechanism of ferrocene with molecular oxygen

Фомин, В. М.; Маркин, А. В.

doi:10.1007/s10973-007-8119-3

Cited by 17 publications

(14 citation statements)

References 7 publications

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“…The oxidation of membrane-bound ferrocene units destabilizes liposomes and causes them to release their contents through a mechanism that is not fully elucidated. The capacity of molecular oxygen to oxidize ferrocene increases significantly in acidic media, 44 but if the oxidation of bilayer-appended ferrocene units induces disorder in the gelphase membrane (as inferred from previous work 13,45 ), then a shift in the observed T m values to lower temperatures would be expected. The same effect was observed in control bilayers that did not contain ferrocene lipids, confirming that the observed shifts were (a) not unique to ferrocene-containing bilayers and (b) not necessarily indicative of an increasingly disordered gelphase bilayer structure.…”

Section: ■ Results and Discussionmentioning

confidence: 85%

EDTA-Gradient Loading of Doxorubicin into Ferrocene-Containing Liposomes: Effect of Lipid Composition and Visualization of Triggered Release by Cryo-TEM

et al. 2021

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Efficient delivery of therapeutic compounds to their sites of action has been a ubiquitous concern throughout the history of human medicine. The tumor microenvironment offers a variety of endogenous stimuli that may be exploited by a responsive nanocarrier, including heterogeneities in redox potential. In the early stages of the design of such responsive delivery systems, it is necessary to develop a comprehensive understanding of the biophysical mechanism by which the stimulus response occurs, as well as how the response may change from the inclusion of cargo compounds. We describe the optimization of lipid compositions for liposomes containing synthetic ferrocene-appended lipids to achieve highly efficient loading of doxorubicin via an ethylenediaminetetraacetic acid (EDTA) gradient. Liposomes containing ferrocenylated phospholipid are shown to be unstable to the loading conditions, while those including a ferrocenylated alkylammonium amphiphile obtain a near-quantitative loading efficiency. Calorimetric studies demonstrate that this instability is the consequence of the relative degree of lipid hydrolysis that occurs under the acidic loading conditions. Drug-loaded liposomes of the optimized composition are studied by cryo-TEM; the presence of doxorubicin aggregates is observed inside vesicles, and doxorubicin release, as well as the changes in membrane structure resulting from oxidant treatment, is also observed by cryogenic transmission electron microscopy (cryo-TEM). These results further demonstrate the potential of ferrocene lipids in the design of redox-responsive nanocarriers and begin to explore their possible role as probes of membrane dynamics.

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Section: ■ Results and Discussionmentioning

confidence: 85%

EDTA-Gradient Loading of Doxorubicin into Ferrocene-Containing Liposomes: Effect of Lipid Composition and Visualization of Triggered Release by Cryo-TEM

et al. 2021

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“…However, this raises the question of the generation of the Fc + species required for such a process. In the absence of strong acids, Fc is resistant to oxidation by molecular oxygen . Consequently, this may suggest electron transfer to the Ru(III) centers of the complexes, leading to generation of EPR-silent Ru(II) and paramagnetic Fe(III) species.…”

Section: Resultsmentioning

confidence: 99%

Induction of Cytotoxicity in Pyridine Analogues of the Anti-metastatic Ru(III) Complex NAMI-A by Ferrocene Functionalization

Mu¹,

Chang²,

Prosser³

et al. 2015

Inorg. Chem.

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A series of novel ferrocene (Fc) functionalized Ru(III) complexes was synthesized and characterized. These compounds are derivatives of the anti-metastatic Ru(III) complex imidazolium [trans-RuCl4(1H-imidazole) (DMSO-S)] (NAMI-A) and are derived from its pyridine analogue (NAMI-Pyr), with direct coupling of Fc to pyridine at the 4 or 3 positions, or at the 4 position via a two-carbon linker, which is either unsaturated (vinyl) or saturated (ethyl). Electron paramagnetic resonance (EPR) and UV-vis spectroscopic studies of the ligand exchange processes of the compounds in phosphate buffered saline (PBS) report similar solution behavior to NAMI-Pyr. However, the complex with Fc substitution at the 3 position of the coordinated pyridine shows greater solution stability, through resistance to the formation of oligomeric species. Further EPR studies of the complexes with human serum albumin (hsA) indicate that the Fc groups enhance noncoordinate interactions with the protein and help to inhibit the formation of protein-coordinated species, suggesting the potential for enhanced bioavailability. Cyclic voltammetry measurements demonstrate that the Fc groups modestly reduce the reduction potential of the Ru(III) center as compared to NAMI-Pyr, while the reduction potentials of the Fc moieties of the four compounds vary by 217 mV, with the longer linkers giving significantly lower values of E1/2. EPR spectra of the compounds with 2-carbon linkers show the formation of a high-spin Fe(III) species (S = 5/2) in PBS with a distinctive signal at g = 4.3, demonstrating oxidation of the Fe(II) ferrocene center and likely reflecting degradation products. Density functional theory calculations and paramagnetic (1)H NMR describe delocalization of spin density onto the ligands and indicate that the vinyl linker could be a potential pathway for electron transfer between the Ru and Fe centers. In the case of the ethyl linker, electron transfer is suggested to occur via an indirect mechanism enabled by the greater flexibility of the ligand. In vitro assays with the SW480 cell line reveal cytotoxicity induced by the ruthenium ferrocenylpyridine complexes that is at least an order of magnitude higher than the unfunctionalized complex, NAMI-Pyr. Furthermore, migration studies with LNCaP cells reveal that Fc functionalization does not reduce the ability of the compounds to inhibit cell motility. Overall, these studies demonstrate that NAMI-A-type compounds can be functionalized with redox-active ligands to produce both cytotoxic and anti-metastatic activity.

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“…And it can be converted to imine G either by an aldehyde pathway in the presence of water or via hemiaminal F by coupling directly with another molecule of benzyl amine. The HPF 6 gets hydrolyzed to generate HF, in the presence of which ferrocene gets converted back to the ferrocenium ion, with dioxygen to complete the catalytic cycle, in the course of the reaction, through the transition state H . ,, The relatively lower efficiency of the BF 4 ̅ counterion stabilized catalyst may be explained by the more facile hydrolysis of the BF 4 ̅ counterions compared to PF 6 ̅ ions, thereby making the overall catalytic cycle less effective with lower turnover. Studies on the hydrolysis of BF 4 ̅ and PF 6 ̅ based ionic liquids support this observation …”

Section: Resultsmentioning

confidence: 99%

Ferrocenium Promoted Oxidation of Benzyl Amines to Imines Using Water as the Solvent and Air as the Oxidant

Deb

Hazra

Dolui

et al. 2018

ACS Sustainable Chem. Eng.

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A ferrocenium promoted method for the chemoselective oxidation of benzylic amines to imines has been developed with yields varying from 53% to 93%. Use of 5 mol % ferrocenium hexafluorophosphate as a promoter was sufficient for this radical based oxidation reaction. Air was bubbled into the reaction mixture, which worked as the oxidant for this transformation. Most importantly, the reaction was carried out in pure aqueous medium at 65 °C. A 10 gram scale reaction with benzylamine was successfully carried out to show the practical applicability of this methodology.

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Oxidation mechanism of ferrocene with molecular oxygen

Cited by 17 publications

References 7 publications

EDTA-Gradient Loading of Doxorubicin into Ferrocene-Containing Liposomes: Effect of Lipid Composition and Visualization of Triggered Release by Cryo-TEM

EDTA-Gradient Loading of Doxorubicin into Ferrocene-Containing Liposomes: Effect of Lipid Composition and Visualization of Triggered Release by Cryo-TEM

Induction of Cytotoxicity in Pyridine Analogues of the Anti-metastatic Ru(III) Complex NAMI-A by Ferrocene Functionalization

Ferrocenium Promoted Oxidation of Benzyl Amines to Imines Using Water as the Solvent and Air as the Oxidant

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