Electron transfer to and from molecules containing multiple, noninteracting redox centers. Electrochemical oxidation of poly(vinylferrocene)

Flanagan, James; Margel, Shlomo; Bard, Allen J.; Anson, Fred C.

doi:10.1021/ja00481a040

Cited by 656 publications

(542 citation statements)

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“…In the other solvents the change in solubility with the change in oxidation state is more pronounced. For example, in THF oxidation of (2)n results in precipitation of the polymer onto the electrode surface, as was also found in electrochemical studies of polyvinyl ferrocene 21 in THE. During the reverse scan, the polymer redissolves as it is reduced.…”

Section: Synthesis Of Ferrocene-containing Homopolymers and Block Copsupporting

confidence: 59%

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Albagli¹,

Bazan²,

Wrighton³

et al. 1992

J. Am. Chem. Soc.

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REPORT DOCUMENTATION PAGEReproduction in whole or in part is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited. it is not oxidized at potentials up to 1.0 V. An analogous initiator containing a ferrocenylmethylidene ligand (ib) can be synthesized by treating la with vinylferrocene. Redoxactive derivatives of norbornene, containing ferrocene (2) or phenothiazine (3) were prepared and polymerized by la or lb to give living block copolymers containing the ring-opened norbornene derivatives. The living polymer was cleaved from the metal in a Wittig-like reaction with pivaldehyde, trimethylsilylbenzaldehyde, or octamethylferrocenecarboxaldehyde. Polydispersities for the longer block copolymers containing up to -80 monomer units was found to be as low as 1.05 by GPC. In one case the polydispersity of a homopolymer made from the ferrocenecontaining monomer was determined by FD-Mass Spectroscopy to be 1.06. DSC studies suggest that microphase formation occurs in the block copolymers, even in the case of relatively low 4 molecular weight materials. Solution voltammetric studies of homo and block copolymers showed that the redox centers were electrochemically independent, and that all centers exchanged electrons with the electrode. Neutral polymers became insoluble upon oxidation to a polycation, yielding an adsorbed polymer layer on the electrode that could then be cathodically stripped. This oxidative deposition process depended on the electrolyte and the polymer molecular weight, but also could be controlled by the size of a non-electroactive block ir the block copolymers. Problems resulting from precipitation of the redox polymers could be circumvented by employing normal pulse voltammetry. Polymers containing redox-active centers in both end groups, as well as in the polymer chain itself, have been prepared and shown in electrochemical studies to undergo the expected initiation, propagation, and termination reactions.

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Section: Synthesis Of Ferrocene-containing Homopolymers and Block Copsupporting

confidence: 59%

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Albagli¹,

Bazan²,

Wrighton³

et al. 1992

J. Am. Chem. Soc.

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“…10 A model ferrocene derivative, 12 poly(vinylbenzyl aminomethyl) ferrocene was synthesized with molecular weight of M n = 271 kDa. Details of the synthesis and characterization of the ferrocene RAP are shown in the Supporting Information (Section 1.0).…”

Section: Methodsmentioning

confidence: 99%

Scanning Electrochemical Microscopy and Hydrodynamic Voltammetry Investigation of Charge Transfer Mechanisms on Redox Active Polymers

Burgess

Hernández‐Burgos

Simpson

et al. 2015

J. Electrochem. Soc.

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We recently showed that viologen-based redox active polymers (RAPs) with molecular weights between 21 and 318 kDa are attractive charge storage materials as anolytes for size-selective non-aqueous redox flow batteries. Here, we characterize the electron transfer mechanisms of these RAPs, as well as a ferrocene based catholyte RAP, in acetonitrile/Li + electrolyte. We utilized scanning electrochemical microscopy (SECM) and rotating disk electrode (RDE) voltammetry to measure the rate of electron transfer and the rate of charge hopping between neighboring pendants along the insulating backbone of RAPs. The electron transfer kinetics of a 271 kDa ferrocene RAP mimic the facile kinetics of its monomer repeating unit. In contrast, viologen RAPs displayed RDE and SECM signatures that suggest a preceding chemical step to electron transfer. Viologen RAPs adsorb strongly to the electrode surface and create a redox active film that controls the rate of electron transfer via self-exchange. In addition, finite element simulations including a preceding chemical step demonstrated that a purely mass-transfer limited model is insufficient to recreate the viologen RAP feedback SECM response. Non-aqueous redox flow batteries (NRFBs) are emerging technologies for electrical energy storage, and are an attractive alternative to their aqueous counterparts. [1][2][3][4][5][6] The choice of organic solvents with voltage windows larger than that required for the electrolysis of water enables the use of a larger variety of redox molecules and electrolyte systems, where the combination of high solubility and higher reaction potentials leads to increased energy density. A major challenge in NRFBs is to increase the conductivity of the electrolyte through the commonly used ion exchange membrane. In response to this challenge, our groups recently reported on a new size-selective concept in flow batteries where a porous separator replaces poorly performing ion exchange membranes.7-9 These porous separators are coupled to high energy density redox active polymers (RAPs) that replaced small molecules as charge storage media. RAPs consist of an unconjugated polymer backbone densely decorated with redox active pendants. We previously reported on the electrochemical characterization of viologen-based RAPs with molecular weight between 21 and 318 kDa, which displayed hydrodynamic radii between 4 and 7 nm. Increasing the size of RAPs decreased transport through Celgard which was used as a porous separator. However, we are also interested in understanding the impact of size on the rate and mechanisms of charge transfer and transport on RAPs to determine their ultimate performance limit. 10RAPs displayed attractive electrochemical properties such as similar standard reduction potentials than those of the parent monomer, efficient bulk electrolysis with up to +98% of redox groups reversibly accessible, and high solubility of up to 2.8 M with quantitative electrode reactivity even when at 1.0 M. Despite these promising features, little is known about el...

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“…The metal centres located at the dendritic periphery are organized in dendrons in such a way that the two metal centres of the dendrons are electronically communicating. Redox reactions of transition-metal complexes [19][20][21][22] are essential to organize molecular electronic communication in nanomaterials 23 . The redox-rich iron centres in the chosen system are Cp Ã Fe II (dppe)-alkynyl units (Cp Ã ¼ Z 5 -C 5 Me 5 , dppe ¼ 1,2-bis(diphenylphosphino) ethane) 24 that are isolobal to ferrocene and linked in meta position of an aryl bridge.…”

mentioning

confidence: 99%

Metallodendrimers in three oxidation states with electronically interacting metals and stabilization of size-selected gold nanoparticles

et al. 2014

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Metallodendrimers containing redox-robust centres may have applications in molecular redox recognition, sensing, biosensing and catalysis. So far, however, no metallodendrimer is known in several oxidation states. Here we report metallodendrimers with two electronically communicating iron centres that are stable and isolated in both the Fe II and Fe III oxidation states, and in addition as class-II mixed-valent Fe II Fe III complexes. These dendrons are branched to arene-centred dendrimer cores either by Sonogashira coupling or 'click' reactions. The latter reaction involves the introduction of intradendritic 1,2,3-triazolyl ligands, which allows investigation of the selective role of these ligands in intradendritic Au III coordination and Au 0 nanoparticle stabilization. As a result, and using the various metallodendrimers with different oxidation states, small Au 0 nanoparticles are intradendritically stabilized by the triazole ligands, whereas with the related non-'click' dendrimers large Au 0 nanoparticles are formed outside the dendrimers and stabilized by a group of dendrimers.

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Electron transfer to and from molecules containing multiple, noninteracting redox centers. Electrochemical oxidation of poly(vinylferrocene)

Cited by 656 publications

References 1 publication

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Scanning Electrochemical Microscopy and Hydrodynamic Voltammetry Investigation of Charge Transfer Mechanisms on Redox Active Polymers

Metallodendrimers in three oxidation states with electronically interacting metals and stabilization of size-selected gold nanoparticles

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