Sulfoxide and Sulfone Synthesis via Electrochemical Oxidation of Sulfides

Park, Jin Kyu; Lee, Sunwoo

doi:10.1021/acs.joc.1c01657

Cited by 35 publications

(35 citation statements)

References 75 publications

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“…The thiophene structural units may be susceptible to oxidative conversion into corresponding sulfones and sulfoxide derivatives, a behavior observed in other conjugated polymer-based electrodes . While such oxidation could explain the observed permanent loss of conjugation observed in the spectroelectrochemical experiments, such oxidation generally requires low-pH environments or H 2 O 2 , both of which have been systematically ruled out and are independent of the electrode identity. A possible candidate for degradation chemistry may be C–S bond scission of thiophenes adsorbed on Au surfaces, which may explain the contribution of bare Au electrodes in accelerating degradation, though how this would affect the film beyond the Au/polymer interface is not clear.…”

Section: Resultsmentioning

confidence: 97%

Sources and Mechanism of Degradation in p-Type Thiophene-Based Organic Electrochemical Transistors

Schafer

Meli

et al. 2022

ACS Appl. Electron. Mater.

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Achieving high stability is critical for the implementation of organic electrochemical transistors (OECTs) in more diverse and demanding applications. However, the sources and mechanisms of OECT degradation have not been rigorously explored. Here, we employ a variety of biasing schemes to separate the relative effects of oxidative bias stress, reductive bias stress, and current stress on degradation of thiophene-based, p-type OECTs. We find that accelerated degradation arises from the compounding effects of simultaneous oxidative and reductive bias stress and is common across several thiophene-based channel materials. To understand the underlying mechanism of OECT channel degradation, we explore the individual contributions of dissolved oxygen and source-drain electrode materials. We determine that the reaction of dissolved oxygen at the buried Au/OMIEC interface of the drain electrode experiencing reductive potentials produces a mobile reactive species that aggressively degrades the oxidized OMIEC throughout the device, destroying its conjugation and disrupting electronic charge transport. Importantly, we find that this mechanism can be disrupted by alternatively removing oxygen, avoiding reductive potentials in the device biasing scheme, replacing Au electrodes with a noncatalytic alternative, or passivating Au electrodes with self-assembled monolayers. These conclusions can inform both future standards of stability testing in the field as well as design considerations of OECT implementation in long-term applications.

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Section: Resultsmentioning

confidence: 97%

Sources and Mechanism of Degradation in p-Type Thiophene-Based Organic Electrochemical Transistors

Schafer

Meli

et al. 2022

ACS Appl. Electron. Mater.

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show abstract

“…The present flavin‐catalyzed electrochemical system with a constant potential (−0.60 V) selectively promoted the oxygenation of the sulfide moiety, and its selectivity after 2 h of reaction reached 85% (Scheme 2A). In this case, the terminal voltage was 1.6 V. The green non‐catalyzed electrochemical oxygenation of sulfides using water as the oxygen source has recently been reported; in this process, the synthesis of sulfoxides or sulfones can be switched by changing the applied voltage or current [9a,d] . However, the non‐catalyzed system could not achieve the chemoselective oxygenation of 4 q because of the side reaction of the alkene moiety, which is likely due to its relatively higher terminal voltage (4.0 V; Scheme 2B) in comparison with that in the flavin‐catalyzed system (1.6 V; Scheme 2A).…”

Section: Methodsmentioning

confidence: 92%