bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single Benzene Yellow Fluorophore: Anodic Synthesis of Tetrahydrobenzodifuran
Authors: Okada Yohei , Wang Zimo , Horiguchi Genki , Kamiya Hihidero 
Published: February 2024

Fluorophores have proven to be indispensable tools in fields ranging from physics, chemistry, and biology. Organic fluorophores have high degrees of freedom in their molecular designs, which is essential for fundamental applications such as imaging probes. The strategies to produce organic fluorophores with improved physicochemical properties are two-fold, including an extension of aryl systems and a construction of push-pull motifs, where electron-donating and -withdrawing groups are conjugated. When used in bio-related research fields, the construction of push-pull motifs is preferred in terms of water solubility and molecular size, since the extension of aryl systems produces relatively large hydrophobic, planar, and thus highly crystalline, structures.
The early work by Shimizu in 2009 triggered explosive growth in the development of new single-benzene fluorophores. From the viewpoints of synthetic practicality and unique and tunable photophysical properties, installing diagonally symmetrical substitution patterns with the same electron-donating and -withdrawing groups is the simplest strategy to create new single-benzene fluorophores.
During the course of our studies focusing on electrochemical cycloadditions, we found that dihydrobenzofuran derivatives armed with electron-donating and -withdrawing groups exhibited bright fluorescence. In order to suppress molecular motions that cause non-radiative transitions, formation of a furan ring is effective in restricting bond rotation. Furthermore, we found that symmetrically substituted dialkoxy-dicarbonylbenzenes exhibited unique bright fluorescence. In this study, we successfully demonstrate that constructing symmetrical push-pull motifs in combination with restricting bond rotations is the key to creating small yet brightly emitting fluorophores. The anodically constructed tetrahydrobenzodifuran moiety has proven to be an effective core architecture to realize unique and powerful single-benzene fluorophores with high quantum yields and large Stokes shifts.
A Molecular Copper Catalyst for Electrochemical Conversion of CO2 to C2+ Products
Authors: Liu Na , Liang Hong Qing , Wohlrab Sebastian , Francke Robert 
Published: February 2024

Electrochemical carbon dioxide reduction (CO2RR) is a promising route to address the excessive emission of CO2 and the depletion of fossil fuels.[1] Metallic Cu and Cu-based materials have attracted increased attention, as Cu is the only metal that can reliably convert CO2 into hydrocarbons and oxygenates, such as ethanol, ethylene, and n-propanol.[2] To optimize CO2-to-C2+ conversion, considerable efforts were made to modify the catalyst composition and structure, adjusting the electrolyte, and optimizing the electrochemical setup.[3] In this context, molecular catalysts (i.e. transition metal complexes) are interesting alternatives, since the performance can be precisely tuned via ligand modification and due to the possibility for mechanistic studies at well-defined and uniform active sites.[4]
Herein, a catalytic system based on an immobilized dinuclear Cu phenanthroline complex is reported that can be prepared with a straightforward synthetic method. The catalyst exhibits excellent CO2RR selectivity toward C-C coupling in aqueous electrolytes with only small production of H2. The highest Faradaic efficiency (FE) for C2+ products achieved was 62% at -1.85 V vs. Ag/AgCl with less than 10% FE for H2. Furthermore, a steady current density and a stable FE(C2H4) over 10 h continuous operation indicate a good stability of the Cu complex. In this contribution, both the electrolysis results and the relationship between structural aspects and product selectivity will be discussed, the latter based on scanning/transmission electron microscopy, X-ray photoelectron/absorption spectroscopy, and further analytical techniques.
Literature:
[1] X. Su, Z. Jiang, J. Zhou, H. Liu, D. Zhou, H. Shang, X. Ni, Z. Peng, F. Yang, W. Chen, Z. Qi, D. Wang, Y. Wang, Nat. Commun.
2022, 13, 1322. [2] W. Quan, Y. Lin, Y. Luo, Y. Huang, Adv. Sci.
2021, 8, e2101597. [3] J. Yu, J. Wang, Y. Ma, J. Zhou, Y. Wang, P. Lu, J. Yin, R. Ye, Z. Zhu, Z. Fan, Adv. Funct. Mater.
2021, 31. [4] D. H. Nam, P. De Luna, A. Rosas-Hernandez, A. Thevenon, F. Li, T. Agapie, J. C. Peters, O. Shekhah, M. Eddaoudi, E. H. Sargent, Nat. Mater.
2020, 19, 266.
Genetic Code Expansion in the Service of Bioelectrochemistry
Authors: Alfonta Lital , Algov Itay , Boyarski Anastasya , Zhou Lu , Cohen Yael , Moshel Itay , Shaferman Michael , Meijler Michael 
Published: February 2024

Genetic code expansion is a method that enables the inclusion of unnatural amino acids (UAAs) into proteins by expanding the genetic code beyond the 20 canonical amino acids. This can be accomplished by introducing new codons (triplet sequences that encode specific amino acids) into the genetic code via orthogonal tRNA/synthetase pairs.
Orthogonal tRNA/synthetase pairs are comprised of aminoacyl-tRNA synthetases (aaRSs) and tRNAs that are not present in nature. These pairs can recognize and charge UAAs with tRNAs that possess non-natural codons, allowing for the integration of these amino acids into proteins in response to non-sense codons.
In our laboratory, we utilize this approach to incorporate various UAAs, some of which serve as orthogonal chemical handles for "clicking" them with redox-active molecules or biomolecules (via click chemistry) or for attaching them to electrodes to enable site-specific orientation of enzymes. Some UAAs are redox-active on their own, which imparts new properties to the proteins and enzymes into which they are incorporated for biosensing and catalysis. In my presentation, I will outline a simple straightforward technique developed in our lab for selecting new UAAs-compatible aaRSs and provide examples and electrochemical characterizations from our recent investigations.	Genetic code expansion is a method that enables the inclusion of unnatural amino acids (UAAs) into proteins by expanding the genetic code beyond the 20 canonical amino acids. This can be accomplished by introducing new codons (triplet sequences that encode specific amino acids) into the genetic code via orthogonal tRNA/synthetase pairs.
Orthogonal tRNA/synthetase pairs are comprised of aminoacyl-tRNA synthetases (aaRSs) and tRNAs that are not present in nature. These pairs can recognize and charge UAAs with tRNAs that possess non-natural codons, allowing for the integration of these amino acids into proteins in response to non-sense codons.
In our laboratory, we utilize this approach to incorporate various UAAs, some of which serve as orthogonal chemical handles for "clicking" them with redox-active molecules or biomolecules (via click chemistry) or for attaching them to electrodes to enable site-specific orientation of enzymes. Some UAAs are redox-active on their own, which imparts new properties to the proteins and enzymes into which they are incorporated for biosensing and catalysis. In my presentation, I will outline a simple straightforward technique developed in our lab for selecting new UAAs-compatible aaRSs and provide examples and electrochemical characterizations from our recent investigations.
A Low-Cost, Safe and Anion-Flexible Method for the Electrosynthesis of Diaryl Iodonium Salts
Authors: Scherkus Anton , Müller Bernd H. , Francke Robert 
Published: February 2024

Hypervalent iodine compounds have been studied extensively in the past. They are considered to be non-toxic and mild oxidants which represent useful alternatives to toxic heavy-metal based reagents.[1] Hypervalent iodine(III) and iodine(V) species such as (diacetoxy)iodobenzene (PIDA) and the Dess-Martin periodinane are commercially available and routinely employed in oxidation reactions.[2] For synthesis of both iodine(III) and iodine(V) species, electrochemical approaches have been developed.[3] The electrochemistry of diaryl iodonium salts (see Figure, compound 3), however, is much less explored. Such compounds are typically employed as versatile arylation reagents.[4] Their conventional synthesis starts from a iodoarene that undergoes a reaction with a chemical oxidizer, followed by subsequent treatment with aryl-boron, aryl-silicon or aryl-tin reagents to yield the diaryl iodonium salt.[4] A more practical approach that does not require activated arenes is based on the use of meta-chloroperbenzoic acid (mCPBA) in presence of a strong acid (e.g. triflic acid) for oxidative C-I coupling.[5]

Using electric current as an oxidizer constitutes a further advancement for synthesis of diaryl iodonium salts. In a recent example, the electrolytic transformation of iodoarenes has been carried out in a HFIP-MeCN solvent mixture using excess triflic acid as the supporting electrolyte and anion source, rendering aryliodonium triflates in medium to high yields.[6]

However, the dependence on the hazardous and costly HFIP and triflic acid still represents a major limitation. In this work, the development of a cheaper, greener, and acid-free synthesis of diaryl iodonium salts is presented.[7] The method uses MeCN as the sole solvent as well as lithium salts as supporting electrolyte/anion source. Since many lithium salts with weakly coordinating anions are commercially available and well soluble in MeCN, the approach provides flexibility regarding the choice of the anion.
[1] a) A. Yoshimura, V. V. Zhdankin, Chem. Rev.
2016, 116, 3328-3435; b) B. Olofsson, I. Marek, Z. Rappoport, PATAI's Chemistry of Functional Groups, John Wiley & Sons, 2018.
[2] a) C. H. Willgerodt, J. Prakt. Chem.
1886, 33, 154-160; b) D. B. Dess, J. C. Martin, J. Org. Chem.
1983, 48, 4155-4156.
[3] a) R. Francke, Curr. Opin. Electrochem.
2019, 15, 83-88; b) R. Francke, Curr. Opin. Electrochem.
2021, 28

[4] E. A. Merritt, B. Olofsson, Angew. Chem. Int. Ed.
2009, 48, 9052-9070.
[5] M. Bielawski, M. Zhu, B. Olofsson, Adv. Synth. Catal.
2007, 349, 2610-2618.
[6] M. Elsherbini, W. J. Moran, Org. Biomol. Chem.
2021, 19, 4706-4711.
[7] A. Scherkus, B. H. Müller, R. Francke, 2023; manuscript in preparation.

Figure 1
Synthetic Chemistry and Microelectrode Arrays: Building Stable Platforms for Point of Care Diagnostics
Authors: Moeller Kevin D , Chang Yu-Chia , Huang Albert 
Published: February 2024

Molecular diagnostics typically require three main components. A molecular interaction that identifies a specific target, a device that detects, quantifies, and records that interaction, and an interface between the two. The interface is critical because it provides a means to fix molecular recognition elements to the surface of the device. For a "point-of-care" application, the interface must be stable both in terms of chemistry and time while still allowing the signal from the molecular interaction to be sensed and recorded by the device. For the use of a microelectrode array as the detection device, construction of the interface must also allow for individual molecular recognition elements to be placed by individual, addressable electrodes in the array.
Because of the need for stability and synthetic flexibility, we made the choice to move away from the use of self-assembled monolayers as the interface for developing microelectrode arrays as point-of-care devices. To that end, we have employed diblock copolymers to coat the surface of microelectrode arrays, a change that has offered increased stability of the surface and enabled the use of a broad array of synthetic methods for functionalizing the electrodes in the array. In this talk, we show how the use of a diblock copolymer in conjunction with Cu(I)- and Cu(II)-mediated reactions can be used to functionalize a microelectrode array with multiple DNA-aptamers for the multiplex detection of metabolites. The resulting surface is stable for over 30 weeks (and counting), allows for the detection of multiple metabolites in the same experiment, and retains the detection sensitivity obtained with a self-assembled monolayer.
One of the goals of the talk will also be to illustrate for the synthetic community the role that it can play in developing new tools for molecular diagnostics. After all, it is the surface on a microelectrode array that in the long-run defines what an array can be used for and the quality of the resulting analytical experiments. The construction of those surfaces is a synthetic chemistry challenge that moving forward will require both new synthetic methods and new approaches for characterization of the products generated from the new methods. One approach for characterization will be discussed in the context of the Cu(I)- and Cu(II)-mediated reactions employed in the current study.
(Invited) Electrochemical Multi-Electron Oxidation of Thiophene-Derivatives Promoted by Coordination of Electrolytes
Authors: Shida Naoki 
Published: February 2024

Supporting electrolyte is an essential component of the electrochemical systems, although its effect on the reactivity of electrochemically generated cation/anion species has been rarely discussed.[1][2] Our recent study on the electrochemical behavior of tellurium-containing π-conjugated molecule revealed that the coordination of anion species toward the electrochemically generated radical cation species determines the number of electrons, where 1e/2e oxidation were switched depending on the donor number of electrolyte-derived anion species as well as solvents.[3]

In the present study, we expanded this idea to thiophene-derivatives to explore the synthetic applicability of electrolyte-coordination. As expected, electrolyte-dependent oxidation behavior of π-expanded thiophene derivatives was confirmed. Especially, the use of coordinating anion promoted multi-electron oxidation of thiophene derivatives, which enabled facile C-C coupling chemistry and oxidative intramolecular cyclization to give rare thiophenium motif in a single step. This study implies the importance of a rational design of the electrolyte to develop novel electrosynthetic reactions.
[1] N. Shida, Electrochemistry, 2022, 90, 101004
[2] S. Yoshinaga, M. Atobe, N. Shida, Electrochemistry, in press (DOI: 10.5796/electrochemistry.23-67013)
[3] N. Shida, H. Nishiyama, F. Zheng, S. Ye, D. S. Seferos, I. Tomita, S. Inagi, Commun. Chem.
2019, 2, 124.

Figure 1
(Invited) Increasing the Reproducibility and Stability of Temperature-Responsive Elastin-like Polymer Surfaces
Authors: Halpern Jeffrey M , Feeney Stanley , Higgins Grace , Sims Myranda , Albeshir Zahraa , Arnold Galen , Waters Jeffery , Balog Eva Rose M 
Published: February 2024

The coacervation versus solubility of Elastin-Like Polymers (ELPs) in solution can be triggered by different factors including ionic strength and temperature. Therefore, the Lower Critical Solution Temperature (LCST) response of ELPs is relatively well understood. However, tethered or surface-bound ELPs are less understood, and the surface reproducibility and stability still needs to be characterized.
Recently our group studied the electrochemical impedance spectroscopy (EIS) response of ELP-modified surfaces associated with changes in ionic strength, and we observed intermediate states of ELP surface collapse.1 Within this work, we present our progress on monitoring the thermal response of surface-bound ELP. Using EIS, We will examine the localized temperature-triggered collapse for I40 ELP (AGCAG(VPGIG)40VPASW). We aim to better understand the way charge transfer changes within a range of temperature and intermediate states. We will report on observed changes in charge transfer resistance from 5 to 40 degrees Celsius. We will discuss protocols we developed to increase the reproducibility of these surfaces. We will also discuss our progress in making these surfaces more stable by looking at the longevity of these surfaces over time.
Support was provided by a National Science Foundation EPSCoR award (#2119237).
[1] Morales, M.A., Paiva, W.A., Marvin, L., Balog, E.R.M. and Halpern, J.M., 2019. Electrochemical characterization of the stimuli-response of surface-immobilized elastin-like polymers. Soft matter, 15(47), pp.9640-9646.
Utilising Fourier Transform Voltammetry to Advance the Enzyme Electrochemistry Toolkit
Authors: Lloyd-Laney Henry , Yates Nicholas , Stapleton James , Hewson Alice , Baranska Natalia , Bond Alan , Gavaghan David , Parkin Alison 
Published: February 2024

Electron transfer and redox chemistry drives life and Biology can provide inspiration for the design of sustainable fuel catalysts that achieve highly active and selective small molecule transformations. In particular, the Parkin group are interested in hydrogenases,1 biological H2-producing enzymes, and lytic polysaccharide monooxygenases (LPMOs),2, 3 enzymes that breakdown cellulose. We seek to understand how the rate and energetics of electron transfer controls catalysis in such enzymes;4 to do this we collaborate with the Gavaghan and Bond groups to develop more powerful bioelectrochemical methodologies.5 This talk will describe our most recent efforts to integrate sinusoidal voltammetry into our enzyme-electrochemistry toolkit.6, 7 The technique offers advantages in terms of simulation speed, which in turn enables the powerful application of Bayesian statistical analysis to visualise the uncertainty in the modelling approach. However, we still rely on large amplitude Fourier transform voltammetry and direct current methodologies to visualise the Faradaic current and readily define redox reaction parameter bounds.
References:
[1] H. Adamson, M. Robinson, J. J. Wright, L. A. Flanagan, J. Walton, D. Elton, D. J. Gavaghan, A. M. Bond, M. M. Roessler and A. Parkin, J. Am. Chem. Soc., 2017, 139, 10677-10686.
[2] P. J. Lindley, A. Parkin, G. J. Davies and P. H. Walton, Faraday Discuss., 2022, 234, 336-348.
[3] J. Branch, B. S. Rajagopal, A. Paradisi, N. Yates, P. J. Lindley, J. Smith, K. Hollingsworth, W. B. Turnbull, B. Henrissat, A. Parkin, A. Berry and G. R. Hemsworth, Biochem. J., 2021, 478, 2927-2944.
[4] A. R. Dale-Evans, M. J. Robinson, H. O. Lloyd-Laney, D. J. Gavaghan, A. M. Bond and A. Parkin, Front. Chemistry, 2021, 9.
[5] H. Adamson, A. M. Bond and A. Parkin, Chem. Comm., 2017, 53, 9519-9533.
[6] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. D. Firth, D. M. Elton, J. Zhang, A. M. Bond, A. Parkin and D. J. Gavaghan, Anal. Chem., 2021, 93, 2062-2071.
[7] H. O. Lloyd-Laney, N. D. J. Yates, M. J. Robinson, A. R. Hewson, J. Branch, G. R. Hemsworth, A. M. Bond, A. Parkin and D. J. Gavaghan, Journal of Electroanalytical Chemistry, 2023, 935, 117264.
(Keynote) Reversible CO2 Reduction Electrocatalysis in Solar-Powered Chemistry
Authors: Reisner Erwin 
Published: February 2024

Semi-artificial photosynthesis interfaces biological catalysts with synthetic materials such as electrodes or light absorbers to overcome limitations in natural and artificial photosynthesis. The benefit of using biocatalysts in electrocatalytic CO2 reduction is their electrochemical reversibility that enables their operation at very low overpotentials with high selectivity. This presentation will summarise my research group’s progress in integrating the CO2 reducing enzyme formate dehydrogenase into bespoke hierarchical 3D electrode scaffolds and the exploitation in solar-powered catalysis. I will present the electrochemical features and characterisation of the biocatalyst-material interface and provide my team's understanding of the electrochemical properties of the immobilised formate dehydrogenase. This insight allows the wiring of the biocatalyst into electrocatalytic schemes, photoelectrochemical devices and photocatalytic systems for unique CO2 utilisation reactions. The fundamental insights gained by integrating isolated formate dehydrogenase in electrodes will be presented and the case be made that this enzyme allows opening a solar-to-chemical conversion space that is currently not accessible with purly synthetic or biological catalysts (see uploaded Image as example).
Recent publications: (1) Lam et al., Angew. Chem. Int. Ed., 2023, in print. (2) Bhattacharjee et al., Nat. Synth., 2023, 2, 182-92. (3) Badiani et al., J. Am. Chem. Soc., 2022, 144, 14207-16. (4) Cobb et al., Nat. Chem., 2022, 14, 417-24. (5) Edwardes Moore et al., Proc. Natl. Acad. Sci. USA, 2022, 119, e2114097199. (6) Anton Garcia et al., Nat. Synth. 2022, 1, 77-86.
Reviews: (1) Fang et al., Chem. Soc. Rev., 2020, 49, 4926–52. (2) Zhang & Reisner, Nature Rev. Chem., 2020, 4, 6–21. (3) Kornienko et al., Acc. Chem. Res., 2019, 52, 1439–44. (4) Kornienko et al., Nature Nanotech., 2018, 13, 890–99
Formation of Arylsulfinates Using Electroreductive Cleavage of Cone-Calix[4]Arene Nosylates – EPR and Theoretical Study
Authors: Liška Alan , Klíma Jiří , Ludvík Jiří 
Published: February 2024

Nosylates are used as protecting groups. In a non-redox hydrolytic process, the leaving group is the corresponding sulfonate anion. Upon electrochemical reduction of nosylates (here six cone-calix[4]arene-bis-nosylates; i.e. 4-nitrophenylsulfonate aryl esters) using mercury electrodes (DC-polarography and cyclic voltammetry - CV) combined with in-situ EPR-spectroelectrochemistry in aprotic DMF, the mechanism is different. All studied calix[4]arene-bis-nosylates are reduced in a first reversible step to bis-nitroradical anion) which was proved by EPR. The stability of the multiple radical ions proves the absence of electron communication among the redox centers on the calixarene macrocycle which was observed previously in other systems1-3.
In the second reduction step next 2×2 electrons are transferred and both sulfonate ester groups are cleaved to two 4-nitro-benzenesulfinate ions and a calixarene bis-phenolate (95%) under splitting of the S-O bond.4 The mechanism of electroreductive generation of arylsulfinate anions is a significant finding from electrosynthetic point of view. Synthesis of activated arylsulfinates is generally difficult for their low stability. Nevertheless, they can be easily prepared by electrochemical reduction of calixarene nosyl esters.

Acknowledgement

This work was supported by the grant GAČR 21-23261S (Czech Science Foundation) with the institutional support RVO: 61388955. The authors are grateful to colleagues ing. Markéta Řezanková, prof. Jan Budka and prof. Pavel Lhoták (University of Chemistry and Technology, Prague) for synthesis and granting the substances.

References:

[1] Liška, A., Vojtíšek, P., Fry, A. J., Ludvík, J. (2013) The Journal of Org. Chem., 78(21), 10651-10656.
[2] Liška, A., Rosenkranz, M., Klíma, J., Dunsch, L., Lhoták, P., Ludvík, J. (2014) Electrochimica Acta, 140, 572-578.
[3] Liška, A., Vojtíšek, P., Ludvík, J. (2019) Chemical Communications, 55(19), 2817-2820.
[4] Liška, A., Řezanková, M., Klíma, J., Urban, J., Budka, J., Ludvík, J. Electrochem. Sci. Advances, DOI:10.1002/elsa.202100221.