Cathodic Reactions of Hydrocarbons, Olefins, and Aromatic Compounds

Heınze, Jürgen

doi:10.1002/9783527610426.bard080004

Cited by 3 publications

(4 citation statements)

References 230 publications

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“…The negative potential shift of R3 corresponds to the difference of ca. 250 mV in the reduction potentials of free pyrene and phenanthrene [ 53 ].…”

Section: Resultsmentioning

confidence: 99%

Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Kearney,

Brandon,

Coleman

et al. 2023

Molecules

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Three novel rhenium N−heterocyclic carbene complexes, [Re]−NHC−1−3 ([Re] = fac−Re(CO)3Br), were synthesized and characterized using a range of spectroscopic techniques. Photophysical, electrochemical and spectroelectrochemical studies were carried out to probe the properties of these organometallic compounds. Re−NHC−1 and Re−NHC−2 bear a phenanthrene backbone on an imidazole (NHC) ring, coordinating to Re by both the carbene C and a pyridyl group attached to one of the imidazole nitrogen atoms. Re−NHC−2 differs from Re−NHC−1 by replacing N−H with an N−benzyl group as the second substituent on imidazole. The replacement of the phenanthrene backbone in Re−NHC−2 with the larger pyrene gives Re−NHC−3. The two−electron electrochemical reductions of Re−NHC−2 and Re−NHC−3 result in the formation of the five−coordinate anions that are capable of electrocatalytic CO2 reduction. These catalysts are formed first at the initial cathodic wave R1, and then, ultimately, via the reduction of Re−Re bound dimer intermediates at the second cathodic wave R2. All three Re−NHC−1−3 complexes are active photocatalysts for the transformation of CO2 to CO, with the most photostable complex, Re−NHC−3, being the most effective for this conversion. Re−NHC−1 and Re−NHC−2 afforded modest CO turnover numbers (TONs), following irradiation at 355 nm, but were inactive at the longer irradiation wavelength of 470 nm. In contrast, Re−NHC−3, when photoexcited at 470 nm, yielded the highest TON in this study, but remained inactive at 355 nm. The luminescence spectrum of Re−NHC−3 is red−shifted compared to those of Re−NHC−1 and Re−NHC−2, and previously reported similar [Re]−NHC complexes. This observation, together with TD−DFT calculations, suggests that the nature of the lowest−energy optical excitation for Re−NHC−3 has π→π*(NHC−pyrene) and dπ(Re)→π*(pyridine) (IL/MLCT) character. The stability and superior photocatalytic performance of Re−NHC−3 are attributed to the extended conjugation of the π−electron system, leading to the beneficial modulation of the strongly electron−donating tendency of the NHC group.

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“…The negative potential shift of R3 corresponds to the difference of ca. 250 mV in the reduction potentials of free pyrene and phenanthrene [ 53 ].…”

Section: Resultsmentioning

confidence: 99%

Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Kearney,

Brandon,

Coleman

et al. 2023

Molecules

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“…Electrochemical reduction offers molecular synthesis by means of cathodic reductive electrolysis to generate radical-anions. ,, This strategy was successfully applied for the reduction of various functional groups such as aldehydes, ketones, esters, or amides . An early example of electrochemical Birch reduction of benzene was disclosed by Kashimura, who employed Mg electrodes, LiClO 4 as a supporting electrolyte, and t -BuOH as a proton donor in dry THF to afford 1,4-cyclohexadienes 58 as the related product .…”

Section: Electrochemical Reduction For Unique Chemoselectivities and ...mentioning

confidence: 99%

“…Specifically, electrophotochemistry combined the electrochemical and photochemical steps in tandem pathways to generate a highly reactive intermediate, thus providing new avenues for contemporary reaction design and molecular transformations. , The merger of electrosynthesis with transition metal catalysis enabled novel resource-economic bond functionalizations, which unearthed a variety of new reaction mechanisms . Electrochemical reduction shows largely untapped potential for reductive organic syntheses through cathodic reduction with the aid of a sacrificial anode material . Enantioselective electrosynthesis, a key research arena which is highly relevant for pharmaceutical and crop-protecting industries, provides greener synthetic methods unattainable by traditional means (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Organic Electrochemistry: Molecular Syntheses with Potential

et al. 2021

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Efficient and selective molecular syntheses are paramount to inter alia biomolecular chemistry and material sciences as well as for practitioners in chemical, agrochemical, and pharmaceutical industries. Organic electrosynthesis has undergone a considerable renaissance and has thus in recent years emerged as an increasingly viable platform for the sustainable molecular assembly. In stark contrast to early strategies by innate reactivity, electrochemistry was recently merged with modern concepts of organic synthesis, such as transition-metal-catalyzed transformations for inter alia C–H functionalization and asymmetric catalysis. Herein, we highlight the unique potential of organic electrosynthesis for sustainable synthesis and catalysis, showcasing key aspects of exceptional selectivities, the synergism with photocatalysis, or dual electrocatalysis, and novel mechanisms in metallaelectrocatalysis until February of 2021.

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“…Next, is the nucleation and growth of short oligomeric structures from the soluble oligomers found along the diffusion layer surrounding the electrode. This step has been ascertained by chronoamperometric experiments through 2D or 3D nucleation and growth mechanisms. − Finally, longer polymeric chains are formed by redox reaction …”

Section: Advances In the Structures Mechanism And Properties Of Polyt...mentioning

confidence: 99%

Molecular Design, Synthetic Strategies, and Applications of Cationic Polythiophenes

Carreon-Asok

2019

Chem. Rev.

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This review delves into the synthesis of cationic-functionalized oligothiophenes and polythiophenes, their properties, and their diverse applications from the year 2002 to 2019. Pristine polythiophene chains are hydrophobic and are not easily converted into a form that is useful for broad applications or for device fabrications. Functional modification of the polymer side chain especially with cationic pendant groups imparts favorable properties to the system, such as solubility in aqueous medium and affinity with anions and negatively charged species, alongside the extensive π conjugation that provides unique optoelectronic characteristics. This review provides a detailed account of the design and the different synthetic strategies to access cationic polythiophenes (CPTs) via chemical oxidation using iron(III) chloride (FeCl 3 ), via metal catalyzed and initiated polymerization, and via postpolymerization functionalization approaches. CPTs have been traditionally used in sensing and as a component in optoelectronic devices; the utility of these systems has been extended to biomedical applications, such as nonviral gene delivery, cell targeting and imaging, anticancer, antifungal, and bactericidal actions, and biofilm formation, and to use as a molecular probe. A summary and outlook are also presented, discussing the remaining challenges and the future direction for this field.

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Cathodic Reactions of Hydrocarbons, Olefins, and Aromatic Compounds

Abstract: The sections in this article are Introduction Reductive Generation of Anionic Species Experimental Background Redox Properties Electron‐transfer Kinetics Chemical Reactions of Electrogenerated Anions Homogeneous Electron Transfer Electro… Show more

Cited by 3 publications

References 230 publications

Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Organic Electrochemistry: Molecular Syntheses with Potential

Molecular Design, Synthetic Strategies, and Applications of Cationic Polythiophenes

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