bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrocatalytic Semihydrogenation of Alkynes to Z-Alkenes Using a Proton Exchange Membrane Reactor: Influence of Catalyst Materials on Product Selectivity and Reaction Rate
Authors: Atobe Mahito , Nogami Shuji , Minoshima Juri , Fukazawa Atsushi , Nagasawa Kensaku , Mitsushima Shigenori 
Published: May 2020

Z-alkenes are versatile building blocks in organic synthesis and often found in pharmaceuticals, perfumes, and natural products. Although a number of methods for stereoselective synthesis of Z-alkene have been developed so far, the Lindlar semihydrogeneation of alkynes is a long-standing synthetic transformation and still remains a privileged system. However, it used toxic Pb additive and a large amount of quinolone, and has other limitations such as narrow substrate scope. Therefore, development of a powerful and reliable system for stereoselective semihydrogenation of alkyne to Z-alkene as alternative to the Lindlar catalytic system is still challenging target.
Under these backgrounds, we have demonstrated electrocatalytic hydrogenation in a proton exchange membrane reactor so called PEM reactor to develop a powerful and reliable stereoselective semihydrogenation system. Especially, in this work, we have investigated systematically influences of catalyst materials such as Pt, Pd, and PtPd alloy for a PEM reactor on the product selectivity for Z-stilbene and partial current density for Z-stilbene formation in the hydrogenation of diphenylacetylene. As a result, PtPd alloy with a composition of 1(Pt):99(Pd) was found to be a most suitable catalyst material in order to achieve both high Z-stilbene selectivity and high partial current density for Z-stilbene formation (Figure 1).
The authors gratefully acknowledge support by JST CREST Grant No. JPMJCR18R1, Japan.
Ref. A. Fukazawa, J. Minoshima, K. Tanaka, Y. Hashimoto, Y. Kobori, Y. Sato, M. Atobe, ACS Sustain. Chem. Eng.
2019, 7, 11050-11055.

Figure 1
Highly Diastereoselective Anodic Fluorination of Organosulfur Compounds Based on Neighboring Participation
Authors: Furuta Shoji , Inagi Shinsuke , Fuchigami Toshio 
Published: May 2020

Highly diastereoselective and efficient anodic α-fluorination of phenyl, p-chlorophenyl, and 2-naphthyl 3,3,3-trifluoro-2-methoxypropyl sulfides was successfully carried out at platinum electrodes in Et3N-nHF (n = 3-5)/MeCN to provide the corresponding α-fluorinated products in good yields, whereas the corresponding p-methoxyphenyl sulfide derivative gave much lower diastereoselectivity. On the basis of such marked substituent effects on the diastereoselectivity and a previous study of anodic methoxylation of related sulfides,1) as well as the X-ray analysis of the configuration of the major diastereomer of the electrochemically fluorinated alph-naphthyl derivative, it was clarified that the high diastereoselectivity is attributable to the neighboring MeO group participation to the anodically generated cationic intermediate destabilized by an electron-withdrawing CF3 group.2)

References:
1. M. Isokawa, M. Sano, K. Kubota, K. Suzuki, S. Inagi, and T. Fuchigami, J. Electrochem. Soc., 164, G121 (2017).
2. S. Furuta, S. Inagi, t. Fuchigami, J. Electrochem. Soc., 166, G110 (2019).
Electrochemical Sulfonylation of Electron-Rich Aromatic Substrates with Sodium Sulfinates
Authors: Nikl Joachim , Lips Sebastian , Waldvogel Siegfried R. 
Published: May 2020

The use of electricity in organic synthesis is characterized by various advantages over conventional methods in terms of reaction selectivity, safety, and sustainability.[1] The use of electrons as reagents, as well as precise reaction control, allows direct C–H bond activation, resulting in less reagent waste. The combination of supporting electrolyte and coupling component, therefore, has a particularly positive effect on the atomic efficiency. Regarding this, we present an electrochemically driven synthesis of various aryl and diaryl sulfones,[2] which amongst others are an important structural motif in pharmaceutical active ingredients.[3] This electrochemical protocol, based on boron-doped diamond electrodes (BDD) and 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP) as solvent, leads to a direct C–S coupling of electron-rich aromatic substrates with sodium sulfinates. The last ones are used combinatorially as supporting electrolytes and coupling components, which makes this method a sustainable contribution to the organic synthesis of sulfones.

References

[1] a) H. J. Schäfer, C. R. Chim. 2011, 14, 745– 765; b) A. Wiebe, T. Gieshoff, S. Möhle, E. Rodrigo, M. Zirbes, S. R. Waldvogel, Angew.
Chem. Int. Ed. 2018, 57, 5594– 5619; Angew. Chem. 2018, 130, 5694– 5721.
[2] a) J. Nikl, S. Lips, D. Schollmeyer, R. Franke, S. R. Waldvogel, Chem. – Eur. J.
2019, 25, 6891–6895; b) J. Nikl, D. Ravelli, D. Schollmeyer, S. R. Waldvogel, ChemElectroChem.
2019, 6, 4450–4455.
[3] a) M. Feng, B. Tang, S. H. Liang, X. Jiang, Curr. Top. Med. Chem. 2016, 16, 1200– 1216; b) D. C. Meadows, J. Gervay-Hague, Med. Res.
Rev. 2006, 26, 793– 814.

Figure 1
Electrochemical Intramolecular C–S Bond Formation Leading to Thienoacene Derivatives
Authors: Mitsudo Koichi , Yonezawa Toki , Matsuo Ren , Suga Seiji 
Published: May 2020

The formation of carbon-sulfur bond is one of the fundamental and significant transformations in organic synthesis because C-S bonds are abundant and significant skeleton in the field of pharmaceuticals and material science. For instance, thienoacene derivatives, such as [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and dinaphtho[2,3-b:2’,3’-d]thiophene (DNT), have received considerable attention as key building blocks for organic field effect transistors (OFETs).
Recently, several novel methods for the construction of carbon-heteroatom bonds have been reported. In particular, electrochemical C–H activation reactions have received considerable attention as straightforward and attractive approaches for the construction of C–O, C–N, and C–S bonds. However, to the best of our knowledge, there has been no report on the application of the electrochemical C–S bond formation for the synthesis of thienoacene derivatives, although they should be a simple and attractive approach to thienoacene derivatives.
From this perspective, we are focusing on an electrochemical C–S bonds formation for the synthesis of thienoacene derivatives, such as [1]benzothieno[3,2-b]benzo[2,3-d]furan (BTBF) and [1]benzothieno[3,2-b]benzo[2,3-d]thiophene (BTBT). We herein report the first electro-oxidative dehydrogenative C–S bond formation promoted by electrogenerated [Br+] for the synthesis of BTBF and BTBT.

Figure 1
Electrochemistry of Nanoscale Hybrid Materials (NOHM) Complexes
Authors: Zawodzinski Thomas A. , Bruce Maria , Park Ah-Hyung , Hamilton Sara Triana , Cantillo Nelly M. 
Published: May 2020

Nanoparticle organic hybrid materials, also known as NOHMs, are composite particles formed by polymers grafted (either ionically or covalently) onto surface-modified inorganic nanoparticles. The unique structure and liquid-like properties of such material have promoted the interest on its application as an electrolyte with the potential to capture and carry nonpolar electroactive species.
In this work two types of NOHMs are considered. Both systems comprise silica cores ionically grafted with polymer tails. The polymer tails correspond to polyethylimine for the NOHM-I-PEI, and to polyetheramine with a sulfonic acid linker for the NOHM-I-HPE.
Cyclic voltammetry was used to investigate the interaction of NOHM-I-PEI and NOHM-HPE with copper. NOHM-I-PEI showed a significant pH influence, with peak inhibition occurring at high pH. The protonation behavior of PEI and NOHM-I-PEI was explored (Figure 1). CV results suggest a strong binding of the copper ions and a potential competition between protons and metal ions. Copper hydroxide formation can also occur at higher pH. In contrast, onset potential shift was observed in presence of NOHM-I-HPE.
These studies are complemented by exploration through Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR). Through EPR, the nature of the ion in solution can be explored. On the other hand, 13C T1 relaxation of the NOHM-based electrolyte at different compositions provide information on the dynamics of the grafted polymers in solution

Figure 1
Scanning Electrochemical Potential Microscopy Imaging Horseradish Peroxidase on HOPG
Authors: Zhang Baohua , Stimming Ulrich 
Published: May 2020

Electrochemical scanning tunneling microscopy (EC-STM) has been successfully applied to study the electron-transfer (ET) reactions of biomolecules at solid-liquid interfaces.1–4 However, there are still limitations, including requirement of sample conductivity and potential damage to the biomolecules from strong tunneling current, to be overcome.
A different type of probe microscopy, scanning electrochemical potential microscopy (SECPM), can be used as a promising alternative. SECPM shares the similar hardware setup with EC-STM, except for the current amplifier being substituted by a potentiometer to measure the local electrochemical potential as feedback signal. This feature enables SECPM to work on less conductive biomolecular samples. It has been shown that SECPM is capable of imaging horseradish peroxidase (HRP) at single molecular level under in situ conditions, with image resolution comparable or even better than EC-STM (Figure 1). 5

The electrochemical double layer (EDL) existing at the solid-liquid interface in an electrochemical cell can be investigated by SECPM using tip-distance curves. Preliminary results will be shown.
In this work, we use SECPM to image HRP molecules adsorbed on HOPG under in situ conditions, with varying electrochemical potentials applied to the substrate. HRP redox reactions were controlled by varying the substrate potential, and the corresponding change of the potential distribution in the EDL covering the adsorbed HRP surface was recorded by SECPM. The experimental results could offer a novel perspective to understand how the ET reactions influences the EDL, and then help the further research on biosensors and EDL capacitors.
This work is supported in part by the North-East Centre for Energy Materials (EP/R021503/1) funded by EPSRC.
References:
1. E. P. Friis et al., Proc. Natl. Acad. Sci., 96, 1379–1384 (1999)
2. Q. Chi, O. Farver, and J. Ulstrup, Proc. Natl. Acad. Sci., 102, 16203–16208 (2005)
3. M. Wang, S. Bugarski, and U. Stimming, Small, 4, 1110–1114 (2008)
4. M. Wang, S. Bugarski, and U. Stimming, J. Phys. Chem. C, 112, 5165–5173 (2008)
5. C. Baier and U. Stimming, Angew. Chemie - Int. Ed., 48, 5542–5544 (2009)

Figure 1
Electron Transfer at Photosystem I - Electrode Interfaces: Porous & Translucent Indium Tin Oxide Cathodes
Authors: Wolfe Kody , Dervishogullari Dilek , Stachurski Christopher , Passantino Joshua , Jennings G. Kane , Cliffel David E. 
Published: May 2020

Biohybrid photovoltaics leverage naturally occurring photo-active protein complexes to convert solar energy into electricity; offering a unique route to lowering the cost and environmental impact of solar energy conversion. Photosystem I (PSI), a protein complex found in higher plants, algae, and cyanobacteria, produces photoexcited excitons over a distance of approximately 10 nm with a 1.1 V photopotential. PSI has been utilized in a variety of biohybrid photovoltaics with success; however, improvements in performance are necessary to bring PSI – based devices to a technologically viable state. The electrons and holes produced within a PSI biohybrid photovoltaic must pass through multiple interfaces before being harnessed in an electrical circuit. Therefore, the total current, potential, and efficiency are dependent on losses incurred at each interface and could be vastly improved by optimizing individual electron transfer steps.
Many researchers are looking toward direct electron transfer (DET) between the active sites of PSI and electrodes to reduce these losses. Unfortunately, achieving DET is difficult due to the necessity of proper PSI orientation and the close proximity (<1 nm) of the active sites to the electrode material for electron tunneling. Alternatively, mediated electron transfer (MET) can be employed through the use of soluble redox mediators to shuttle charge between the active sites and electrodes. MET can benefit from the use of high surface area electrodes and increased loadings of PSI. Our group has studied both DET and MET within PSI bioelectrodes of various architectures. In this presentation, the incorporation of PSI into porous and translucent indium tin oxide (ITO) cathodes to achieve significant improvements in MET will be highlighted. Additionally, the limitations and challenges of DET, directions for improving MET in porous electrodes, and future prospects for improving charge transfer at PSI – electrode interfaces will be discussed.
Electrochemical Characterization of Carboplatin Toward the Detection of Drug Resistance in Cancer
Authors: Luu Huy Tran Le , Nachtigal Mark , Kuss Sabine 
Published: May 2020

Epithelial ovarian cancer (EOC) has the highest mortality rate among gynecological cancers and affects patients on all continents. Primary treatments involve surgery and the administration of chemotherapeutics, such as carboplatin, which is listed by the World Health Organization as an essential medication for the treatment of human cancers. Unfortunately, due to high rates of drug resistance of EOC towards carboplatin, cancer relapse rates are devastating, and the mechanisms of chemoresistance to carboplatin have not been adequately identified. Consequently, there is a dire need for innovative strategies that are able to detect carboplatin resistance in cancer and to further our understanding of the fundamental nature of chemoresistance towards carboplatin.
The presented work describes the thorough electrochemical characterization of carboplatin. We quantify the influx and efflux of carboplatin into/from ovarian cancer cells by electrochemistry to better understand mechanisms of carboplatin chemoresistance. Results emerging from this research will be important for future medical research developing novel agents to combat chemoresistance and will present the basis for future long-term funding applications under this collaboration.
Stability Investigations of Platinum Electrodes in Nonaqueous Systems
Authors: Ranninger Johanna , Wachs Susanne J. , Möller Jonas , Mayrhofer Karl J. J. , Berkes Balázs B. 
Published: May 2020

Fundamental understanding of electrode dissolution processes in nonaqueous media is crucial for applications like nonaqueous battery systems, sensors, capacitors but also organic electrochemistry and is inextricably related to economic considerations. The reasons for electrode degradation are among others anodic dissolution, cathodic dissolution or cathodic corrosion. Enhanced knowledge of dissolution mechanisms and factors like composition or structure of electrodes, electrolyte and temperature are important to optimize the operation conditions, limit electrode degradation and increase the lifetime of devices.
The development of the scanning flow cell (SFC) combined with an Inductively Coupled Mass Spectrometer (ICP-MS), allowing online stability studies, has given valuable insights into degradation mechanisms of different electrodes and catalyst materials in aqueous media which are relevant for applications like fuel cells and electrolyzers. We have developed an electrochemical flow cell (EFC) coupled to the ICP-MS which is suitable for the use in aggressive nonaqueous electrolytes. The flow cell is operated in an argon filled glovebox which allows us to conduct electrochemical experiments in completely inert atmosphere under the exclusion of oxygen and water.
Platinum is one of the most extensively studied electrode materials due to its excellent electrocatalytic activity and inertness in various applications. Our novel method allows new insights into the complex behavior of platinum in nonaqueous electrolytes, among others in its dissolution. New aspects regarding the stability of platinum in different nonaqueous electrolytes are unveiled depending on the chemical properties of the solvent and the conducting salt. While the dissolution behavior of completely water free protic electrolytes like methanol and aprotic electrolytes like acetonitrile is very similar, the dissolution behavior changes completely in presence of trace amounts of water. Furthermore, different cations and anions in the electrolyte effect the anodic dissolution and cathodic corrosion, respectively.
The controlled addition of water to nonaqueous electrolytes is an important tool to study the behavior of the formation and dissolution of the platinum oxide passivation layer and is not only relevant for nonaqueous electrocatalysis but also gives new insights into the dissolution mechanisms in aqueous electrolytes.
The details of the method and different platinum dissolution profiles in several nonaqueous electrolytes will be discussed. Additionally, dissolution mechanisms will be proposed based on studies with changing water content.
Nature Inspired Anti-Biofouling Strategy for the Detection of Protein Biomarkers Directly in a Drop of Blood
Authors: Adhikari Bal Ram , vallée-Bélisle Alexis 
Published: May 2020

Electrode biofouling in complex biological fluids is one of the major problems in analytical electrochemistry. Direct electrochemical detection in human blood remains challenging due to quick surface passivation by proteins present in blood, degrading sensor’s sensitivity. This challenge has dramatically slowed down commercialization efforts of point-of-care devices. Here we have developed a simple nature-inspired electrochemical DNA hybridization (e-hyb) assay based on steric hindrance which enable electrodes to detect nanomolar concentration of proteins (i.e. antibody) directlywithin a drop ofblood without any sample preparation. This e-hyb assay involves two DNA strands; one-captured DNA immobilized on electrode surface and another complementary reporter DNA labelled with an electroactive molecule (methylene blue) at one end and a specific recognition element at the another end. In presence of a specific large analyte binding to the small recognition element, the reporter DNA cannot reach to the electrode surface due to steric hindrance. This simple strategy enables us to quantify different protein biomarkers (HIV antibody, anti-DNP antibody, anti-DIG antibodyetc) in human blood without being limited affected by biofouling.
Figure 1: e-DNA hybridization based anti-biofouling strategy for the detection of antibody in human blood

Figure 1
In-Situ TEM Observation of Silver Nanodendritic Growth in Liquid
Authors: Hou Szu-Yu , Huang Chih-Yang , Chen Jui-Yuan , Wu Wen-Wei 
Published: May 2020

Silver nanocrystals with highly branched morphologies are an appealing new series of nanomaterials owing to their unique structures, physicochemical properties, and exceptional potential as catalysts, optics, photography, microelectronics, bactericidal coatings, sensing materials, and building blocks for nanoscale devices. The properties related to their twin structure of the seed particles and the ratios between growth rates of different crystallographic facets of silver dendritic nanostructure. However, there is still a lack of information that how silver dendritic nanostructure growth by based particles aggregation and heterogeneous seed process remain unclear. Therefore, tracking particle growth by in-situ liquid cell transmission electron microscopy (LC-TEM) provides the direct evidence and extends the study of both dendritic nanostructure evolution and growth mechanisms. In this work, we observed the dynamic growth process of silver nanodendritic in solution by liquid cells with high resolution analysis. The following chemical equations describe the formation of Ag0 under electron beam radiation.
H2O → eaq
- + H•+ OH•+ H2O2 + H2 (1)
Ag2+ + 2 eaq
- → Ag (2)
Ag2+ + 2 H• → Ag (3)
The driving force comes from the non-uniformities in local electron does, the radiolysis of water could induce a concentration gradient among the species, which was a particularly significant factor to affect the particles attachment in non-equilibrium conditions resulted in inhomogeneous growth. The accumulation of Ag+ was reduced by electrons resulted in heterogeneous seeded growth of Ag0. The growth mechanisms of silver nanodendritic and aggregation behaviors are systematically studied from the dynamic and kinetic viewpoints, strengthening the knowledge in branched morphologies growth. Without a doubt, the field of synthesis and application of silver nanodendritic will keep moving forward as better understanding of their growth mechanisms are achieved.

Figure 1
Measurement Drift in Electrochemical Impedance Spectroscopy
Authors: Halpern Jeffrey M , Ziino Emily , Marnoto Sabrina 
Published: May 2020

Electrochemical impedance spectroscopy (EIS) is a powerful method that can be used to passively monitor disruptions on a surface. Yet, reproducibility issues associated with repeated impedance measurements using EIS is known.1,2 Often reproducibility issues are associated with differences in the initial state of the surface or quantifiable measurement drift of the EIS response. Measurement drift is of specific concern because it can result in mistaken interpretations of data.
We have been investigating the cause and potential reasons for the electrochemical drift that has been observed. We hypothesize that the charging state of the working electrode influences the observed impedance drift in EIS. We investigated multiple factors to look at the charged state of the working electrode, including removing the working electrode from the solution, reporting the open circuit potential, reporting the double layer capacitance and charge transfer resistance changes, varying the concentration of an electrochemical mediator, changing the ionic strength of the aqueous solution, and DC offset conditions. The run-to-run variation was controlled by waiting 10 min between each run over a period of 1 hour (6 runs in total). Total charge transfer resistance drift varied by over 500 Ohms in the worst conditions and as good as 5 Ohms at the best conditions over six runs, indicating improvements of 2 orders of magnitude. All experimental variable changes were run in triplicate to show experimental error and standard deviations of all runs. Taking these methods into account, the most reproducible model of repeated EIS impedance measurements will be discussed. Further, theories and data to indicate potential causes and solutions will be presented.
Acknowledgements: The authors would like to acknowledge the financial support from NIH (P20 GM113131) NSF (CBET 1638896), and the Hamel Center of Undergraduate Research at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Halpern’s laboratory.
References
1. M. E. Orazem, M. Durbha, C. Deslouis, H. Takenouti, and B. Tribollet, Electrochim. Acta, 44, 4403–4412 (1999).
2. A. Bogomolova et al., Anal. Chem (2009).