bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring the Synergistic Relationship between Organic Synthesis and Electrochemistry
Authors: Moeller Kevin D 
Published: May 2020

Electrochemistry has long held potential as a tool for constructing organic molecules, and the organic chemistry community is both recognizing and impressively exploiting that potential with increasing regularity. Those efforts have taught us a great deal about how to think about electrochemical reactions, how to use the technique to accomplish new transformations that enrich the synthetic enterprise, and when to employ those methods.
Interestingly, the relationship between organic synthesis and electrochemistry can also be viewed in the opposite direction with the new synthetic chemistry being developed serving as a tool to facilitate and dramatically expand the scope of electrochemical methods. For example, new synthetic chemistry that allows for the site-selective generation of chemical reagents on an array have enabled the construction of complex, addressable molecular surfaces that can in turn be used to probe small molecule interactions with a variety of biological targets. The efforts set the stage for using microelectrode arrays as analytical devices for rapidly screening small molecule libraries in "real-time". The methods allow for the construction of libraries with tunable surfaces, careful control of surface concentrations, and previously unknown levels of quality control over the molecular library. The development of an even greater arsenal of synthetic tools for use on the arrays is underway, an effort that aims to expand the nature and size of the addressable libraries that can be used to probe the world around us.
Not surprisingly, the exploration of these new electrochemical tools is beginning to “give back” to the synthetic arena. A number of preparative scale synthetic applications have now arisen based on the concept of site-selective reagent generation. Chief among these is the use of paired electrochemical reactions for more sustainable reagent generation and the recent discovery that chemical reagents can be confined to specific regions within a preparative reaction; a development that potentially offers a new strategy for controlling the selectivity of a chemical reaction.
In the talk to be given, the interplay between organic synthesis and electrochemistry will be highlighted with an emphasis on how key concepts in physical organic chemistry are used to guide the development of new advances in both areas, and how we think those new developments will shape future efforts to expand the use of electroorganic synthesis.
References:
For a recent review see: Kevin D. Moeller. Chem. Rev.
2018, 118, 4817-4833.
Phenolic Antioxidants: Redox Properties and Antioxidant Activities
Authors: Martic Sanela 
Published: May 2020

Phenolic compounds are known for their antioxidant properties, which is important in the biological setting [1]. The cellular damage induced by reactive oxygen species, ROS, or others leads to diseases. However, foods or drugs which contain phenolic moieties are viable antioxidants which reduce ROS and minimize cell damage. Hence, greater understanding of this class of compounds will lead to an ideal antioxidant with tailored properties for applications in biology, food safety, among others. The relationship between structure-properties-function was evaluated by using voltammetric methods. We have explored redox properties of phenol-based compounds, such as tert-butylhydroxyphenol and its analogues by using Cyclic Voltammetry (CV) as well as Square-Wave Voltammetry (SWV) in order to rank order such compounds based on their redox potentials and structural parameters [2]. We have discovered that under electrochemical conditions, rather than chemical ones, such compounds may undergo cross-coupling reactions leading to photochromic products. The reactivity of such phenolic analogues was also explored by CV in the study with reactive oxygen species, specifically, superoxide anion radical [3]. More recently, we have started exploring compounds with multiple hydroxyl groups, such as flavonoids. The research findings on a variety of hydroxyl-containing aromatics will be presented and described.
1. Ingold, K. U., Pratt, D. A. Advances in radical-trapping antioxidant chemistry in the 21st century: a kinetic and mechanisms perspective. Chem. Rev. 2014, 9022-9046.
2. Zabik, N., Virca, C. N., McCormick, T., Martic-Milne, S. Selective electrochemical versus chemical oxidation of bulky phenols. J. Phys. Chem. B, 2016, 120, 8914–8924.
3. Zabik, N., Anwar, S., Ziu, I., Martic-Milne, S., Electrochemical reactivity of bulky-phenols with superoxide anion radical. Electrochim. Acta, 2019, 296, 174-180
Electrosynthesis of Highly Functionalized N,N-Diarylamides and Selective Functionalization of Caffeine Via Electrochemically Generated HFIP Ethers
Authors: Dörr Maurice , Lips Sebastian , Röckl Johannes , Waldvogel Siegfried R. 
Published: May 2020

Most cross-coupling reactions make use of transition metal-based catalysts and require prefunctionalization or an excess of oxidizers. This results in large quantities of partially toxic reagent waste. By anodic cross-coupling via the oxidation of phenols, those drawbacks are avoided.[1] Utilizing simple undivided cells, a safe and sustainable protocol for the synthesis of highly functionalized N,N-diarylamides was presented. This involves the hydrolysis of the initially formed hydrobenzoxazolo-[2,3-b]benzoxazole during a simple work-up procedure.[2] The resulting N,N-Bis(2-hydroxyphenyl)amides are of special interest for the synthesis of crown ethers[3] and biologically active compounds.[4]

Derivatives of caffeine showed biological activities in the past.[5] The selective functionalization of caffeine was now achieved by electrochemically generating the corresponding hexafluoroisopropyl ether and thereby activating it for subsequent metal-catalyzed cross-coupling reactions. Using a “Design of Experiments” approach (DoE) for the optimization of the initial step, detailed information about the system was gathered. This led to the implementation of a fast and selective electrolysis.
[1] 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] M. Dörr, S. Lips, C. A. Martínez-Huitle, D. Schollmeyer, R. Franke, S. R. Waldvogel, Chem. Eur. J.
2019, 25, 7835–7838.
[3] a) T. Németh, A. Kormos, T. Tóth, G. T. Balogh, P. Huszthy, Monatsh. Chem.
2015, 146, 1291–1297; b) S. Lakatos, J. Fetter, F. Bertha, P. Huszthy, T. Tóth, V. Farkas, G. Orosz, M. Hollósi, Tetrahedron
2008, 64, 1012–1022.
[4] M. Farkas, G. Láng, Z. Dinya, P. Sohár, L. Rózsa, Z. Sudai, J. Mol. Struct.
1985, 131, 131–140.
[5] a) J. Pretorius, S. F. Malan, N. Castagnoli, J. J. Bergh, J. P. Petzer, Bioorganic & medicinal chemistry
2008, 16, 8676–8684; b) D. E. Guttman, A. E. Gadzala, Journal of pharmaceutical sciences
1965, 54, 742–746.

Figure 1
Anodic Oxidation of 9,9'-Spiro-Bifluorenes Containing C, Si, Ge and Sn as the Central Elements
Authors: Becker James Y. 
Published: May 2020

Previously we investigated [1] the electrochemical properties of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran.
Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives.
Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products.
References
[1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem.,
2004, 569,
15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem.,
2004,

573, 139-146.
[2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122.
[3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem
,

2019, 6, 1–6.

Figure 1
Electrochemical Oligopeptide Synthesis Assisted By a Soluble Tag Method
Authors: Nagahara Shingo , Okada Yohei , Chiba Kazuhiro 
Published: May 2020

Recently, peptides have attracted much attention as the medicinal candidates with higher specificity and lower side effects than small molecular medicines. Peptides have been synthesized using stoichiometric amount of coupling reagents. While these reagents enable quantitative reaction, stoichiometric byproducts from coupling reagents cause poor atom economy. In this context, “General methods for catalytic/ sustainable (direct) amide or peptide formation” is selected as one of the top research area in green chemistry. [1]

To solve the problem, we are aiming to establish a method of electrochemical oligopeptide synthesis and recycle coupling reagents. Inspired by the report of Uribe’s group, [2] we selected triphenylphosphine (TPP) as the coupling reagent in electrochemical peptide bond formation. Although triphenylphosphine oxide (TPPO) is generated as the stoichiometric byproduct, reduction of TPPO to TPP are achieved in various ways. [3] Therefore, TPP can be a recyclable coupling reagent in peptide synthesis and this lead to reduce the amount of waste. In addition, we employed soluble tags as protecting group of carboxylic acids, which are consisted of benzyl group with long alkyl chain and precipitate in polar solvents, to make purification easier. [4]

Until now, we have succeeded quantitative electrochemical peptide bond formation. Notably, we found that soluble tag serves to prevent undesired oxidation of amino acids maybe because long alkyl chain of soluble tag keep amino acids away from electrode. Work to synthesis bioactive oligopeptides is in progress.
Reference
[1] M. C. Bryan, P. J. Dunn, D. Entwistle, F. Gallou, S. G. Koenig, J. D. Hayler, M. R. Hickey, S. Hughes, M. E. Kopach, G. Moine, P. Richardson, F. Roschangar, A. Steven and F. J. Weiberth, Green Chem., 2018, 20, 5082-5103.
[2] A. Palma, J. Cardenas and B. A. Frontana-Uribe, Green Chem., 2009, 11, 283–293.
[3] Y. Okada, H. Suzuki, T. Nakae, S. Fujita, H. Abe, K. Nagano, T. Yamada, N. Ebata, S. Kim, and K. Chiba, J. Org. Chem., 2013, 78, 320−327.
[4] D. Hérault, D. H. Nguyen, D. Nuel and G. Buono, Chem. Soc. Rev., 2015,
44
, 2508-2528.

Figure 1
Fabrication of TiO2-WO3 Nanopillars for Alcohol Oxidation
Authors: Parihar Amritdev , Hosseini Seyyedamirhossein , Peters Dennis G. 
Published: May 2020

Ethanol, the major component of biofuel mixture, has significantly lower heat capacity compared to that of longer-chain alcohols such as butanol. As a result, oligomerization of ethanol has gained much attention. This three-step process includes: (I) alcohol oxidation to the corresponding carboxylic acid, (II) dimerization via carboxylic acid terminals, and (III) further reduction of the oligomer to form the saturated alcohol.1 In this context, TEMPO has been vastly utilized for the electrochemical oxidation of alcohols, but this process suffers from shortcomings such as limited turnover frequency of the reagent and small conversion yield of the synthesis.2 There have been some reports on the application of semiconductor electrodes for oxidizing certain types of alcohols. This approach, however, has shown some pitfalls such as high oxidation overpotential, low reaction yield, and low stability of the working electrode.3
The goal of this research is to fabricate a novel photoanode for oxidizing alcohols to their corresponding carboxylic acids. In this work, we aimed at fabricating an ordered array of TiO2 nanopillars decorated with WO3 nanoparticles. To prepare such an electrode, silicon oxide nanospheres (SONS) were deposited onto a silicon wafer covered with a 5-nm layer of gold. Then, TiO2 was electrodeposited into the empty hexagonal spaces resulting from SONS forming a tight-packed structure. Subsequently, SONS were washed away and a layer of WO3 was electrodeposited. Our experimental results have shown a homogeneous deposition of the WO3 layer when 60-ms symmetrical pulse cycles of potential (-0.5 V vs. SCE) were applied for 50 min.
References
1. Fu, S.; Shao, Z.; Wang, Y.; Liu, Q. Manganese-Catalyzed Upgrading of Ethanol into 1-Butanol. J. Am. Chem. Soc. 2017, 139, 11941-11948.
2. Rafiee, M.; Miles, K. C.; Stahl, S. S. Electrocatalytic Alcohol Oxidation with TEMPO and Bicyclic Nitroxyl Derivatives: Driving Force Trumps Steric Effects. J. Am. Chem. Soc. 2015, 137, 14751-14757.
3. Hitmi, H.; Belgsir, E. M.; Léger, J.; Lamy, C.; Lezna, R. O. A Kinetic Analysis of the Electro-Oxidation of Ethanol at a Platinum Electrode in Acid Medium. Electrochimica Acta. 1994, 39, 407-415.
Visible Light-Driven Catalytic Reaction Catalyzed By the B12-Rhodium-Titanium Oxide Hybrid Catalyst
Authors: Shimakoshi Hisashi , Shichijo Keita , Hisaeda Yoshio 
Published: May 2020

Organometallic B12 compounds are unique metal complexes having a cobalt-carbon σ-bond present in biological systems [1]. Cleavage of the metal-organic σ-bond initiates many B12 dependent enzymatic reactions. Based on unique properties of B12 enzymes, many B12-inspired reactions were developed [2]. Here we report the visible light-driven new B12 inspired reaction for the fine chemical synthesis [3]. The hybrid catalyst composed of the B12 complex and rhodium ion modified titanium oxide was synthesized for the visible light-driven B12 inspired reaction. Visible light irradiation (λ≧420 nm) of the hybrid catalyst in the presence of a sacrificial reagent showed absorption at 390 nm, typical for the Co(I) state of the B12 complex monitored by diffuse reflectance UV-vis analysis, which imply that electron transfer from the titanium oxide to Co(III) center of the B12 complex occurred by the visible light irradiation. Benzotrichloride was converted to N,N-diethylbenzamide by the visible light irradiation in the presence of triethylamine catalyzed by the hybrid catalyst in air at room temperature. Both the conduction band electron and valence band hole of the catalyst were utilized for the reaction to form the amide product. The reaction mechanism of the duet reaction was proposed. The B12-inspired photocatalyst shown here can be used for the sustainable production of fine chemicals with the possible expense of energy economy.
[1] Review: H. Shimakoshi, Y. Hisaeda, Current Opinion in Electrochem. 2018, 8, 24.
[2] K. Proinsias, A. Jackowska, K. Radzewicz, M. Giedyk, D. Gryko, Org. Lett., 2018, 20, 296.
[3] K. Shichijo, M. Fujitsuka, Y. Hisaeda, H. Shimakoshi, J. Organomet. Chem. 2020, in press.

Figure 1
Shifts of pNIPAM Lower Critical Solution Temperature in an Applied Electric Field
Authors: Halpern Jeffrey M , Roberge Emma , Ren Tianyu , LaFreniere Joelle , Balog Eva Rose M , Seitz William Rudolf 
Published: May 2020

Poly(N-isopropylacrylamide), or pNIPAM, is a free-radical polymer that is commonly studied for uses in surface coatings, tissue engineering, energy storage, biosensing, and more, due to its temperature responsiveness. Below its transition temperature, pNIPAM is dissolved in solution with a small particle size. Above the transition temperature, pNIPAM agglomerates and condenses out of solution. Dynamic Light Scattering (DLS) measures temperature induced agglomeration of pNIPAM by determining the transition temperature, which is typically 30-35oC for pNIPAM. We initially confirmed the lower critical solution temperature (LCST), or the point in which pNIPAM agglomerates, to be thermodynamically reversible and reproducible for both pNIPAM and an electrochemically active poly(N-isopropylacrylamide)-block-poly(ferrocenylmethyl methacrylate) block copolymer, or p(NIPAM-b-FMMA).
Applying a potential across the DLS light path, we expected p(NIPAM-b-FMMA) to cause a shift in the transition temperature and agglomeration behavior. However, we unexpectedly observed a shift in the transition behavior of pNIPAM. At an applied electric field of 400 mV/cm and above, the transition temperature of pNIPAM started to shift negative. Further, upon cooling, the pNIPAM never re-dissolves, indicating an irreversible agglomeration in the presence of an applied.
We have also started to investigate reasons on why this phenomenon might occur. We will discuss two primary hypotheses, including wetting behavior changes of the pNIPAM and further radicalization of the RAFT agents leading to cross-linking and irreversible behavior.
Acknowledgements: The authors would like to acknowledge the financial support from NIH (P20 GM113131), NSF (CBET 1638896), the Collaborative Research Excellence Initiative Pilot Research Program at the University of New Hampshire, and the Hamel Center of Undergraduate Research at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Seitz’s laboratory and Dr. Halpern’s laboratory
Pulsed Voltammetry of an Aspidosperma Alakaloid: Vindoline
Authors: Haque Inam ul , Tariq Muqaddas , Aslam Nishat , Saba Hina 
Published: May 2020

There is steady interest in the chemistry surrounding vindoline [1] and its uses [2]. Of interest are the number of electron(s) involved in the electro-oxidation of its tertiary amine nitrogen and the dihydro-indole nitrogen. Normal pulse voltammetry (NPV) showed two successive one-electron removals respectively from the two nitrogens; essentially in conformity with reported work [3] based on a different technique.
The second electron transfer likely is not reversible as reverse normal pulse voltammetry (RNPV) revealed no first current plateau [4] irrespective of the initial potential(s) selected from the second plateau of the normal pulse voltammogram. On the other hand, anodic cyclic voltammetry of vindoline [5] appears to indicate the formation of its dimers [5, 6] and trimers [7, 8].
[1] Inam ul Haque, Hina Saba, Vindoline and its reactions, Journal of the Chemical Society of Pakistan, 33 (6) 905-915 (2011)
[2] Zhengqiong Zhang, Chengqi Lu, Pei Wang, Aijing Li, Hongbo Zhang, Sichuan Xu, Structural basis and mechanism for vindoline dimers interacting with α,β-tubulin, ACS Omega, 4 (7) 11938-11948 (2019)
[3] Toivo Naaranlahti, Veli-Pekka Ranta, Pekka Jarho, Mervi Nordström, Seppo P. Lapinjoki, Electrochemical detection of indole alkaloids of Catharanthus roseus in high-performance liquid chromatography, The Analyst, 114 (10) 1229-1231 (1989)
[4] C.L. Kulkarni, Barry J. Scheer, James F. Rusling, Potential-sweep and pulse voltammetric investigations of the anodic dimerization of tetrahydrocarbazoles, Journal of Electroanalytical Chemistry, 140 (1) 57–74 (1982)
[5] Inam ul Haque, Voltammetric behaviour of meta-dimethylaminoanisidine at glassy carbon electrode, Journal of the Chemical Society of Pakistan, 12 (3) 256-259 (1990)
[6] Ibro Tabakovic, Katmerka Tabakovic, One pot electrochemical synthesis of 10,10′-bisvindoline by an oxidation-reduction sequence, Tetrahedron Letters, 37 (21) 3659-3662 (1996)
[7] Áron Szigetvári, András Keglevich, Péter Keglevich, Miklós Dékány, László Hazai, Csaba Szántay Jr, A mainly NMR-based structure elucidation of a surprising vindoline trimer with the aid of non-uniform sampled 1H-13C HSQC and HMBC spectra, Structural Chemistry, 30 (3) 795–804 (2019)
[8] Kai Yu, Hong Zhang, Jing He, Richard N. Zare, Yingying Wang, Ling Li, Na Li, Dongmei Zhang, Jie Jiang, In situ mass spectrometric screening and studying of the fleeting chain propagation of aniline, Analytical Chemistry, 90 (12) 7154-7157 (2018)
Fluorescence Mapping of α-Tocopherol Redox Activity in Supported Lipid Bilayers
Authors: Sakaya Aya , Durantini Andres , Sverko Tara , Wieczny Vincent , Cosa Gonzalo 
Published: May 2020

Lipid membranes have gained wide attention as assembly scaffolds, owing to their ability to self-assemble into well-defined fluid structures, allowing the compartmentalization and direct assembly of components of interest in a fluid platform. Model lipid membranes offer the opportunity to mimic and study processes occurring across these fluid mosaics such as respiration, transport and signaling.
Armed with a spectroelectrochemistry microscopy setup, in this study we have explored redox reactions within lipid membranes, proof of concept experiments intended to address the response of membrane embedded redox systems. Experimentally, a supported lipid bilayer was formed on top on an indium tin oxide (ITO)-coated glass. H4BPMHC, a redox sensitive fluorogenic probe bearing the chromanol moiety of α-tocopherol (Vitamin E), and a BODIPY tail segment was incorporated within the lipid membrane. The electrochemical and optical properties were next studied using our total internal reflection fluorescence (TIRF) microscopy based spectro-electrochemical (SEC) setup, that enables monitoring emission while minimizing background by virtue of sampling a small ~ 300 nm region above the glass water interface, while also controlling the redox potential at the basal leaflet of the lipid membrane.
Our results are consistent with oxidation of the chromanol moiety of the probe into a chromanone moiety through an irreversible process that elicits fluorescence, and further thermally induced rearrangement of the newly formed chromanone into a chromoquinone. We will discuss the general methodology, results, and implications of the work in the context of electron transport through relay redox systems.
Improvement of the Performance in Membraneless Aqueous H2O2 Fuel Cells By Electroadsorption of Ad-Anions on the Surface of the Cathodes
Authors: Manriquez Juan , Ortega-Díaz David , Sepúlveda Selene , Bustos Erika , Orozco Germán 
Published: May 2020

Performance of a membraneless aqueous H2O2 fuel cells were significantly improved by assembling prussian blue-modified glassy carbon anodes (GC/PB) and gold cathodes whose surfaces were enriched by H2PO4
- ad-anions (Au/H2PO4
-). In this way, glassy carbon anodes were modified by a potentiostatically-deposited prussian blue (PB = Fe4[Fe(CN)6)]3•xH2O) film, whereas H2PO4
- ad-anions were electroadsorbed on the polycrystalline gold cathodes by means of cyclic voltammetry. The as-prepared electrodes were inserted in H2O2 fuel cells filled by deoxygenated phosphates buffer solutions (PBS, pH 2) containing several initial H2O2 concentrations. A highest power performance of the electrode materials was found by comparing all the discharge curves (potential vs. current plots) obtained as a function of the initial H2O2 concentration fed to the cells. Effect of the gap between the electrodes over the fuel cells performance was previously explored and optimized. The tabulated results below, demonstrate that the performance achieved for the cells constructed in this work was significantly superior to the best performance reported for comparable H2O2 fuel cells. Thereafter, electrochemical impedance spectroscopy (EIS) and a Bisquert type electrical transmission line [2] (data not shown), were employed for better understanding how an optimized electron-transfer kinetics for the Au/H2PO4
- cathodes allowed improving to the fuel cells performance. Finally, our results demonstrated that, once the Au/H2PO4
- cathodes were inserted into the H2O2 fuel cells the fill factor and the maximal power density were improved with the aid of the establishment of a competition between the electrical and ionic conductivities occurring through the PB films at the Au/PB anodes.

open-circuit potential
(mV)

maximal current density
(mA/cm2)

fill factor

maximal power density (mW/cm2)

This work

741±11

13.5±0.4

0.56±0.03

5.6±0.2

Ref. [1]

600

10

0.26

1.6

References:

[1] Y. Yamada, M. Yoneda, S. Fukuzumi, Energy Environ. Sci., 8 (2015) 1698.
[2] J. Bisquert, Phys. Chem. Chem. Phys., 2 (2000) 4185.

Acknowledgements:

The authors thank the Mexican Council for Science and Technology (CONACyT) for its financial support of this work (grant 258789). D.O. acknowledges CONACyT for his PhD scholarship (grant 639209).