bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Electrocatalytic Radical-Polar Crossover Hydrofunctionalization of Alkenes
Authors: Kim Hyunwoo 
Published: February 2024

Due to the unique reactivity of open-shell intermediates, the development of catalytic transformations driven by single-electron transfer (SET) has been an area of intense research in organic chemistry. In particular, the employment of unconventional means of activation, including photoredox catalysis and electrocatalysis, has provided unique entry to single-electron reactivities and led to new solutions to challenging synthetic problems that are not readily addressed using existing tools.
We disclose a general electrocatalytic hydrofunctionalization by utilizing a wide range of alkenes. The integration of the two involves an electrochemically instigated cobalt-hydride-catalyzed radical-polar crossover of alkenes that enable the generation of key cationic intermediates, which could readily be entrapped by challenging nucleophiles. We highlight the importance of precise control of the reaction potential by electrochemistry in conjunction with the decisive role of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the co-solvent to obtain optimal and exclusive chemoselectivity.
In addition, we develope an electrocatalytic method for intramolecular hydroamination of allylic sulfonamides to access azetidines. The merger of cobalt catalysis and electricity enables regioselective generation of key carbocationic intermediates, which could directly undergo intramolecular C-N bond formation. The mechanistic investigations including electrochemical kinetic analysis suggest that the catalyst regeneration by nucleophilic cyclization is involved in the rate-determining step (RDS) of our electrochemical protocol and highlight the ability of electrochemistry in providing ideal means to mediate catalyst oxidation.
(Invited) Delivering Electrons and Protons to the Substrate in Molecularly-Based Reductive Electrocatalysis
Authors: Durin Gabriel , Lee Mi-Young , Kahl Christian , Weyhermüller Thomas , Han Chenhui , Zenner Johannes , Johny Jacob , Bordet Alexis , Kaeffer Nicolas , Leitner Walter 
Published: February 2024

To steer away from fossil fuels the primary sourcing for goods and chemicals, combining renewable electricity with sustainable feedstocks in an electrochemical strategy is a formidable synthetic opportunity. In that frame, we investigate how molecular electrocatalysis can foster electrosynthetic conversions, in particular for organics reductions.[1]

Here, we will disclose that alkyne semihydrogenation, an important synthetic manifold, can be selectively electrocatalyzed by a simple molecular catalyst [Ni(bpy)3]2+, based on the earth-abundant metal nickel.[
2
] Our combined electrochemical, synthetic and computational investigations support that the catalytic cycle proceeds via the protonation of a nickelacyclopropene species and bypasses the need to generate a competent hydride.[3] As a proof-of-concept for molecular electrocatalytic alkyne semihydrogenation, this work opens a platform to develop original electrochemical routes for the hydrogenation/-functionalization of organics and small molecules.
We will also discuss the use of Pickering emulsion that separates organic substrates and aqueous electrolytes in different phases for electrocatalytic hydrogenation at the interface. We developed a hybrid design based on carbon nanotube-supported Pd nanoparticles that places at the interface and acts both as emulsion stabilizer and electrocatalyst. The system electrohydrogenates styrene into ethylbenzene with high faradaic efficiency (95.0%) and Pd specific current density (–148.1 mA·cm–2). Our system combines good solubility of the substrates, high conductivity, facile product isolation and applies to the transformation of various alkenes. This strategy may thus provide original solutions to the ECH of substrates having low water-solubility.[4]

References

[1] N. Kaeffer, W. Leitner, JACS Au,
2022, 2, 1266.
[2] M.-Y. Lee, C. Kahl, N. Kaeffer, W. Leitner, JACS Au,
2022, 2, 573.
[3] G. Durin, M.-Y. Lee, T. Weyhermüller, N. Kaeffer, W. Leitner, ChemRxiv, 10.26434/chemrxiv-2023-whtfd.
[4] C. Han, J. Zenner, J. Johny, N. Kaeffer, A. Bordet, W. Leitner, Nat. Catal., 2022
, 5, 1110.
(Keynote) Electrochemical and Mass Spectrometry Measurements of Nanometer Vesicles
Authors: Ewing Andrew G 
Published: February 2024

We originally developed a tool to measure the chemical messenger contents of single nanometer vesicles starting with capillary electrophoretic separation, lysing and electrochemical detection. We called this flow vesicle impact cytometry (FVIEC). The method used a microfluidic device with sheath flow and electrode for detection. The next generation approaches led to static electrochemical measurements and mass spectrometry imaging of vesicular content. First, micro-/nano-electrochemical approaches have been developed to carry out quantitative measurements of intravesicular content and real-time monitoring of vesicle release dynamics. We have used stochastic vesicle impact electrochemical cytometry (VIEC) and intracellular VIEC (IVIEC) to provide a highly effective way to quantify the electroactive contents inside vesicles. This has allowed direct comparison of the quantity of molecules released by exocytosis to those in the vesicles. Partial release is observed across all cell types examined to date by the electrochemical methods and appears to be regulated.
More recently, we have used mass spectrometry imaging with NanoSIMS as a complimentary approach to image the neurotransmitter dopamine across the internal volume of these incredibly small vesicular structures. We have developed standards to carry out quantitative NanoSIMS and subsequently used it to quantify the chemical contents across the nanometer structure of vesicles. We then used NanoSIMS imaging of dopamine inside and drug into vesicles to quantify the fraction of messenger and demonstrate drug entry during exocytosis providing definitive evidence of partial release and a means to introduce drug into cells.
Real-Time Mass Spectrometry for Simultaneous Monitoring of Electrode Dissolution and Reaction Product Distribution during Organic Electrosynthesis
Authors: Nikolaienko Pavlo , Ranninger Johanna , Berkes Balázs B. , Mayrhofer Karl J. J. 
Published: February 2024

An organic electrosynthesis is an emerging tool for modern chemical manufacturing fitting the environmental and sustainability agenda. It utilizes polarized electrode surfaces as “traceless” oxidants or reductants, whereas its heterogeneous nature and exceptional tunability enable easy access to radical intermediates and novel mechanistic pathways. In the line of further energy input improvement, there is a growing demand for appropriate catalytic materials devoted to organic molecule transformations, for which the activity and selectivity have so far been most studied. Although the investigation of electrodes’ and electrocatalysts’ stability in the field of electrochemical energy conversion is well-established, there is still a lack of attention to the symmetrical studies for organic electrosynthesis. Nevertheless, electrode material losses shorten the reactor’s lifetime and can cause metal cathodic re-depositions, severely altering reaction product selectivity and final product contaminations. Although some reports on the ex-cell metal dissolution analysis are available, no information about its mechanism can be gained in such a way. To highlight the issue numerically, an analytical method to characterize rates and mechanisms of catalyst dissolution within a real-time response-enabled potential-, temperature-, or time-resolved parametrization of the electrocatalyst is highly demanded.
Herein we present a system to study organic electrosynthetic protocols under dynamic operations to quantitatively monitor the electrode dissolution aligned with reaction products during organic molecules transformations. The instrument comprises an electrochemical flow cell (EFC) with exchangeable working electrodes, the outlet of which is interfaced with an online quadrupole mass spectrometer (OQMS) for the analysis of extracted by solid membrane gaseous products and an inductively coupled plasma mass spectrometer (ICP-MS) for the detection of dissolved metals. The system is exemplified by a benchmark Kolbe electrolysis over platinum Pt anode, commonly considered a stable and inert electrode material. Based on the literature, methanol has been used as a solvent of choice, while partially neutralized acetic acids with different bases were studied as objects. The methodology shed some light on understanding the role of platinum oxide formation on the electrode surface and can be used to study time- and potential-resolved catalyst stability and the possibility for dissolved transition metal-catalyzed electroorganic transformations.
Peroxodicarbonate as Versatile Green Oxidizer
Authors: Waldvogel Siegfried R 
Published: February 2024

The electrochemical conversion of aqueous carbonate solutions at boron-doped diamond anodes provides access to an unique oxidizer. The key aspects for a highly efficient electrosynthesis requires a splendid heat dissipation and high concentration of the alkali carbonates. With reaching almost molar concentrations of peroxodicarbonates a novel reactivity is achieved.[1]

This green reagent allows direct epoxidation, S- and N-oxidations, oxidative deborolations and many more useful transformations including the selective Kraft lignin oxidation.[2-4]

References:

[1] A.-K. Seitz, P. J. Kohlpaintner, T. van Lingen, M. Dyga, F. Sprang, M. Zirbes, S. R. Waldvogel, L. J. Gooßen, Angew. Chem. Int. Ed.
2022, 61, e202117563.
[2] A.-K. Seitz, T. van Lingen, M. Dyga, P. J. Kohlpaintner, S. R. Waldvogel, L. Gooßen, Synlett
2022, 33, 1527–1531.
[3] M. Zirbes, T. Graßl, R. Neuber, S. R. Waldvogel, Angew.
Chem. Int. Ed.
2023, 62, e202219217.
[4] P. J. Kohlpaintner, L. Marquart, L. J. Gooßen, S. R. Waldvogel, Eur. J. Org. Chem.
2023, e202300220.
Catalytic Electricity Promoted Electrochemical Synthesis
Authors: Sato Eisuke , Fujii Mayu , Yoshida Haruka , Suga Seiji 
Published: February 2024

Direct electron transfer from organic compounds has been used as a powerful catalyst to promote various chemical transformations. In particular, electrochemical organic synthesis enables both hole-catalyzed (anodic oxidation) and electron-catalyzed (cathodic reduction) transformations. We will present the catalytic cathodic reduction-promoted reactions and the application of an electrochemical flow reactor, which allows efficient transformations. Trimethylsilylcyanide (TMSCN), for example, could be reduced on a cathode, and the corresponding radical anion reacted with carbonyl compounds or imines. The addition reaction only required a small amount of electricity, and the catalytic transformation was achieved.
In addition, the machine learning-assisted conditions optimization of the electrochemical flow synthesis has also been demonstrated. Gaussian process regression (GPR) could illustrate the relationships between the conditions and the reactivities on counter maps. The counter maps suggest that achieve a good yield or time-scale yield of the desired compounds.
Facile Synthesis of Nitrogen Cation-Doped Polycyclic Aromatic Hydrocarbons by Anodic Intramolecular Pyridination
Authors: Inagi Shinsuke , Ohno Yushi , Ando Shogo , Furusho Daisuke , Tomita Ikuyoshi 
Published: February 2024

The bottom-up synthesis of heteroatom-doped polycyclic aromatic hydrocarbons (PAHs) has attracted attention in the development of models of doped graphene. Among PAHs, nitrogen-cation (N
+)-doped PAHs are known to exhibit superior optoelectronic functionalities; however, practical methods for synthesizing N
+-doped PAHs are limited and challenging [1]. In our previous study, the SNAr reaction was used for the intramolecular cyclization of phenylpyridine derivatives possessing an electron-deficient perfluoroaryl moiety to give the corresponding N
+-doped triphenylene in high yields under moderate conditions without the use of a transition-metal catalyst [2,3]. However, one of the challenges in the synthesis of N
+-doped PAHs via the SNAr reaction is poor functional-group tolerance.
Here, a facile and selective synthesis method for N
+-doped PAHs has been established via anodic intramolecular cyclization, inspired by the Yoshida’s protocol for C–H amination without a transition-metal catalyst or an oxidant [4]. The reaction mechanism, in particular the reaction selectivity, was elucidated using density functional theory (DFT) calculations. The N
+-doped PAH products were found to have a donor–acceptor structure composed of an arene moiety and a pyridinium moiety, as evidenced by DFT calculations, UV–vis analysis, and electrochemical measurements. The proposed intramolecular anodic pyridination is a practical strategy for the late-stage introduction of N+ into π-electron systems and broadens the scope of molecular design of N
+-doped PAHs.
References:

J. Liu, X. Feng, Synlett
2020, 31, 211–222

Y. Asanuma, H. Eguchi, H. Nishiyama, I. Tomita, S. Inagi, Org. Lett.
2017, 19, 1824–1827

N. Shida, H. Nishimi, Y. Asanuma, I. Tomita, S. Inagi, Polym.
J.
2020, 52, 1401–1406.

T. Morofuji, A. Shimizu, J. Yoshida, J. Am. Chem. Soc., 2013, 135, 5000–5003.

Figure 1
Electrochemical Reduction of C-O Bonds
Authors: Villo Piret , Lill Malin , Alsaman Zainab , Soto Kronberg Adrian , Chu Victoria , Ahumada Guillermo , Agarwala Hemlata , Ahlquist Mårten , Lundberg Helena 
Published: February 2024

Reductive activation and transformation of C-O bonds in alcohols have been a challenge for many decades, yet is still considered an important step in the process of converting biomass into biofuel and chemicals. The challenge arises from the cleavage of the carbon-oxygen bond which generally requires forcing conditions and is reflected in the high bond dissociation energy compared to other polarised sigma bonds.[1] Our project focuses on electroreductive cleavage of alcohols in the presence of a hydrogen donor in an undivided cell with up to 95% of the corresponding alkane. C-O transformation is also accomplished through carboxylation with carbon dioxide, resulting in yield up to 43%.[2]
[1] Villo, P.; Shatskiy, A.; Kärkäs, M. D.; Lundberg, H. Electrosynthetic C−O Bond Activation in Alcohols and Alcohol Derivatives. Angewandte Chemie International Edition
2023, 62 (4), e202211952. https://doi.org/10.1002/anie.202211952.
[2] Villo, P.; Lill, M.; Alsaman, Z.; Kronberg, A. S.; Chu, V.; Ahumada, G.; Agarwala, H.; Ahlquist, M.; Lundberg, H. Electroreductive Deoxygenative C–H and C–C Bond Formation from Non-Derivatized Alcohols Fueled by Borohydride Oxidation. ChemRxiv August 2, 2023. https://doi.org/10.26434/chemrxiv-2023-tw9l1-v2.

Figure 1
Tetrabutylammonium Borohydride: A Sacrificial Reductant in Organic Electrosynthesis
Authors: Ahumada Guillermo , Lill Malin , Kuzmin Julius , Goossens Ellymay , Steffensen Astrid , Lundberg Helena 
Published: February 2024

In this work, tetrabutylammonium borohydride (TBAB) is investigated as a terminal reductant in reductive organic electrosynthesis as replacement for sacrificial anodes. Sacrificial anodes are typically based on easily oxidized metals, such as Mg, Zn, or Al, and are consumed during the reaction, resulting in stoichiometric metal waste. In contrast, oxidation of TBAB enables the use of inert anodes and results in anodic H2 formation, effectively serving as the inverse of cathodic proton reduction. Our results indicate that TBAB oxidation at carbon-based electrodes can replace the use of sacrificial anodes in several organic electrosynthetic reactions, including Birch reduction, hydrodesulfurization of thioethers, hydrodeoxygenation of alcohols1, and cross-electrophile couplings.
References

Villo, P.; Lill, M.; Alsaman, Z.; Soto Kronberg, A.; Chu, V.; Ahumada, G.; Agarwala, H.; Ahlquist, M.; Lundberg, H. Electroreductive Deoxygenative C–H and C–C Bond Formation from Non-Derivatized Alcohols Fueled by Borohydride Oxidation. ChemElectroChem. 2023, accepted for publication (a previous version can be found in ChemRxiv, DOI: 10.26434/chemrxiv-2023-tw9l1-v2.)

Figure 1
Insights into the Structure Sensitivity of Fe-Based Materials for the Oxygen Evolution Reaction
Authors: Martinez Hincapie Ricardo Alonso , Colic Viktor 
Published: February 2024

The conversion of renewable energy into storable fuels is fundamental to the meeting of the net-zero CO2 emissions objective by 2050. However, the sluggish kinetics of the oxygen evolution reaction (OER) and the poor stability of electrocatalysts at industrial-level currents remain a problem for electrolyzers 1. Using platinum group metal-free electrocatalysts in anion exchange membrane electrolyzers is an appealing strategy to overcome some of the problems associated with PEM electrolyzers. Fe-based materials offer the possibility for the development of active, stable, and cost-effective electrocatalysts for the OER in alkaline media.
In this work, we explore the influence of structure, composition, or crystalline phase on different Fe-based electrodes for the OER. Different fabrication procedures such as additive manufacturing 2, flame spray synthesis, or pulse laser ablation 3 allow us to have a wide range of Fe-based materials with a well-defined structure/composition/phase. The materials have been extensively characterized by physicochemical methods (XPS, Raman, XRD, ICP) and their electrocatalytic activity evaluates following careful procedures in order to obtain reliable results. The results show that the activity of Fe-rich electrodes is poor. However, if Fe is alloyed with other materials or its surface structure or crystallinity degree is modified, it results in a more active material. This information could guide the synthesis of more active and stable water-splitting materials.
References

S. Cherevko, S. Geiger, O. Kasian, N. Kulyk, J.-P. Grote, A. Savan, B. R. Shrestha, S. Merzlikin, B. Breitbach, A. Ludwig, and K. J. J. Mayrhofer, Catalysis Today,
262 170-180 (2016).

J. Wegner, R. Martínez-Hincapié, V. Čolić, and S. Kleszczynski, Advanced Materials Interfaces,
n/a (n/a), 2202499 (2023).

J. Johny, Y. Li, M. Kamp, O. Prymak, S.-X. Liang, T. Krekeler, M. Ritter, L. Kienle, C. Rehbock, S. Barcikowski, and S. Reichenberger, Nano Research,
15 (6), 4807-4819 (2022).
Decoupling Reaction, Diffusion and Ohmic Processes in Fast-Charging Electrodes: A New Model for CV Data Analysis
Authors: ten Elshof Johan E. , Xia Rui , Zheng Jie , Huijben Mark 
Published: February 2024

Fast charging is critical for the efficient storage of energy in devices like electric vehicles and portable electronics. The rate performance of electrodes is limited by the electron transfer rate, the ohmic resistance of the electrode, the size and shape of the primary electrode particles, and the charge carrier diffusion process within the electrodes. However, separating the intrinsic contributions of mass transport and charge transfer from non-equilibrium data obtained under large interfacial polarization is very complex, which limits our understanding of high rate electrodes during charging and discharging. While it is possible to extract the diffusive and capacitive components of an electrode’s capacity from cyclic voltammetry (CV) data using the Dunn method, the Dunn model assumes a constant diffusional overpotential. In reality the ohmic resistance scales with the current, so that the ohmic potential drop across the electrode cannot be neglected a priori for fast charging electrodes in which high current densities are a requirement.
We recently developed a new model based on the Butler-Volmer equation for the kinetics of the electron exchange process, and incorporated the charge carrier diffusion process and the internal ohmic losses, as well as the effect of the shape and dimensions of the primary electrode particles on the effective diffusion rate [1]. The model can provide the relation between current peak voltages and peak currents from a series of sweep rate CV measurements. The ohmic resistance, equilibrium voltage, exchange current (related to the electrochemical reaction rate) and limiting current (related to the charge carrier diffusion coefficient and Nernst diffusion layer thickness) can be extracted as independent variables from the fitted experimental data.
By simulating a range of different high rate Li electrode materials (both cathodes and anodes), we identified influence of the reaction rate on the overpotential as a common significant factor, which explains the nonlinear relation between the potential and the current at peak position in different CV measurements. Our analysis suggests that a higher electrochemical reaction rate seems to be more important for the realization of faster charging batteries than a larger carrier diffusion coefficient.
Finally, our extended model also enables us to predict the overpotential at any applied potential, which is not possible with other current models known till date. This insight helps us to gain more detailed understanding of the relationship between the intrinsic properties of the electrode materials and their rate performance in different reaction stages. This may facilitate further modification of electrode material towards enhanced high rate performance in next-generation batteries.
[1] R. Xia et al., Energy Storage Mater. 53 (2022) 381-390.
Sensor Absorbents for Heavy Metal Ions By Low-Cost Functionalization of Porous Carbons
Authors: Sandberg Mats , Petsagkourakis Ioannis , Beni Valerio 
Published: February 2024

Porous carbons are key materials in electrodes for electrochemical energy storage as well as in water purification. Methods to modify porous carbons to enhance their properties as charge storing or water purification materials have been explored during the past decades [1,2]. The main application fields if porous carbon, water purification and energy storage, are highly cost sensitive. For this reason, there is a need to develop low-cost methods to modify porous carbons. Here, the use of benzoxazine chemistry to modify porous carbons is explored. Benzoxazine chemistry can be considered a protection group strategy for phenols, where the phenols from which the benzoxazines are synthesized, are deprotected upon benzoxazine polymerization. Further, benzoxazine polymerization produces Mannich bridges located near phenol groups, motifs that can be used to capture heavy metal ions. More specifically, in the first step, the porous carbons are partially impregnated with benzoxazine monomers, from melt or solutions to afford powders impregnated far below the liquid saturation level of the particles. That is, the particles retain porosity after the impregnation but still have a dry appearance. After impregnation, the particles are heated over the polymerization temperature of the benzoxazine to afford the porous carbon with immobilized functionalities. As phenols can initiate benzoxazine polymerization and be incorporated in the polymer, this method offers a simple route to produce polymerized and immobilized structure at a carbon interface. Here, results on metal ion absorption and the electrochemical response after exposure are presented for carbons modified by impregnation-polymerization of benzoxazines with or without incorporation of phenols. Inks were manufactured from the modified carbons. The electrochemical characterizations were performed on printed arrays of electrochemical cells on a substrate having dimensions of well plates and intended for automatized testing and where the carbon inks were deposited on the working electrodes. This methodology has a potential of simplifying the development of sensor materials and absorbents and can be automatized and potentially be supported with machine learning schemes. The electrochemical responses of exposure of the modified carbon electrodes to metal salt solutions show that impregnation-polymerization of functional benzoxazine can produce absorbents responding electrochemically to metal ion absorption with a scalable process starting from low-cost materials.
References:
[1] Sultana, et al., Clean. Eng. Tech. 6 (2022) 100382
[2] Pognon et al., J. Pow. Sourc. 196 (2011) 4117