Article
Chemistry, Physical
Tao Wu, Josef Kapitan, Petr Bour
Summary: Chiral metal complexes have rich photophysical properties and are important for various applications. This study combines experimental and computational approaches to investigate the energies and transition moments of excited electronic states in two chiral metal complexes. The experimental protocol involves multiple techniques, and a formula for subtracting interfering effects is provided. Density functional theory calculations are used to analyze the spectra and reveal the geometric and electronic structures of the molecules. This insight into molecular electronic states can be useful for understanding and manipulating the photochemical properties of metal-containing complexes, biomolecules, and supramolecules.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Michael Kemper, Elric Engelage, Christian Merten
Summary: This study demonstrates the efficient transfer of point chirality in side chains of chiral triarylborane-ammonia adducts to the propeller chirality of triarylboranes. By using X-ray crystallography and spectroscopy, the conformational preferences of molecular propellers were elucidated. Interestingly, computationally predicted conformational preferences were found to be opposite to the experimentally observed ones.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Cheng Xu, Zhihao Ren, Hong Zhou, Jingkai Zhou, Dongxiao Li, Chengkuo Lee
Summary: This study investigates the impact of near-field coupling on the chirality response of chiral metamaterials. It is observed that strong near-field coupling induces less chiral response, providing evidence for the assumption. The study also demonstrates the use of enhanced near-field coupling for glucose enantiomer sensing and explores the potential of using arrayed metamaterials for broadband signal detection.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Review
Chemistry, Multidisciplinary
Sascha Jahnigen
Summary: Chirality is a phenomenon that appears in various forms, including molecular and structural chirality. The relationship between molecular chirality and the enantiomorphism of crystals is still an open question that can be addressed with chiroptical tools. Vibrational circular dichroism (VCD) is a chiral infrared spectroscopy that can provide information about both the molecular and intermolecular space. It has become the method of choice for determining absolute configurations and studying crystal forms and polymorphism.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Gui-Fei Huo, Toshiya M. Fukunaga, Xudong Hou, Yi Han, Wei Fan, Shaofei Wu, Hiroyuki Isobe, Jishan Wu
Summary: A facile synthesis method for expanded helicenes was reported in this study, which involves Suzuki coupling-based oligomerization and Bi(OTf)(3)-mediated regioselective cyclization. The structures of the synthesized compounds were determined by X-ray crystallographic analysis. Enantiopure H2, H3, and H4 with high absorption dissymmetry factors (|g(abs)|) were isolated using chiral HPLC, and all of them exhibited strong chiroptical responses.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Physics, Multidisciplinary
Dongsheng Song, Rafal E. Dunin-Borkowski
Summary: This study presents a method for three-dimensional magnetic measurement at atomic scale using EMCD technology, which allows for obtaining signals related to magnetization in three Cartesian directions by using a subangstrom convergent electron beam in STEM. Atomic resolution EMCD signals from all three directions can be separately acquired by moving the detector, and signal enhancement can be achieved by using a defocused electron beam.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Michael Kemper, Sven Reese, Elric Engelage, Christian Merten
Summary: The stabilization of chiral propeller conformations in triaryl compounds is challenging due to low racemization barriers. However, the incorporation of point-chiral alkylether chains and subsequent locking of the structure with ammonia can induce chiral conformational preferences in triaryl boranes. A four-point interaction involving Lewis-adduct formation and three hydrogen bonds was proposed as the stabilizing mechanism. DFT calculations predicted no significant preference for propeller handedness, but vibrational circular dichroism spectroscopy revealed a measurable excess of one propeller handedness. The steric demand of the amine was found to play a key role in the induction process and preventing blade rotations.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Organic
Thierry Brotin, Nicolas Daugey, Josef Kapitan, Nicolas Vanthuyne, Marion Jean, Erwann Jeanneau, Thierry Buffeteau
Summary: This study reports the synthesis and absolute configuration (AC) of a chiral isotopologue of syn-cryptophane-B. Low chiral signatures were measured using polarimetry and electronic circular dichroism, while the most significant chiroptical effects were observed using vibrational circular dichroism (VCD) and Raman optical activity (ROA). By comparing the experimental VCD and ROA spectra with those predicted by DFT calculations, the AC of the two enantiomers was determined as (-)589-MP-syn-2 and (+)589-PM-syn-2.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Multidisciplinary Sciences
Jaehyun Son, Sunihl Ma, Young-Kwang Jung, Jeiwan Tan, Gyumin Jang, Hyungsoo Lee, Chan Uk Lee, Junwoo Lee, Subin Moon, Wooyong Jeong, Aron Walsh, Jooho Moon
Summary: This study deduced the effect of hydrogen-bonding interaction on chirality transfer in inorganic frameworks by using structural isomer with different functional group location. The experimental analysis and crystallography parameters confirmed the crucial role of asymmetric hydrogen-bonding interaction in the spin-related properties of chiral perovskites.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Herman Duim, Maria Antonietta Loi
Summary: This article discusses the potential of chiral hybrid organic-inorganic metal halides (HMHs) in the field of optics, examining the impact of chiral transfer on electronic structure and optical properties. It further explores efforts to improve and tune the chiroptical response, while also proposing future research directions for enhancing chiral HMHs.
Article
Chemistry, Analytical
Daniel W. Armstrong, Jeongjae Yu, Houston D. Cole, Sherri. A. McFarland, Jordan Nafie
Summary: The use of transition metal complexes as cancer therapy agents, particularly non-platinum-based ones, is an area of growing interest. A promising Ru(II) metal-organic dyad has shown effectiveness as a photodynamic therapy agent for certain types of cancer. The recent synthesis, separation, and determination of absolute configurations of chiral Ru(II) and Os(II) PDT agents have provided valuable insights into the development of novel cancer treatments.
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
(2021)
Article
Chemistry, Multidisciplinary
Mengjia Cen, Jiawei Wang, Jianxun Liu, Huilin He, Ke Li, Wenfeng Cai, Tun Cao, Yan Jun Liu
Summary: A new type of self-aligned suspended chiral bilayer metasurface is demonstrated, which can exhibit significant optical chirality and label-free discrimination of chiral molecules at zeptomole level, with higher sensitivity compared to conventional circular dichroism spectroscopy.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Joshua Vogwell, Laura Rego, Olga Smirnova, David Ayuso
Summary: We present an ultrafast all-optical approach for efficient chiral recognition based on the interference between sum-frequency generation and third-harmonic generation. Our method encodes the handedness of the medium in the intensity of the emitted harmonic signal, enabling full control over the enantiosensitive response. By manipulating the sub-optical-cycle oscillations of the driving laser field, we achieve high efficiency in chiral sensitivity via low-order nonlinear light-matter interactions, paving the way for ultrafast and highly efficient imaging and control of chiral molecules.
Article
Materials Science, Multidisciplinary
Wouter Heyvaert, Adrian Pedrazo-Tardajos, Ajinkya Kadu, Nathalie Claes, Guillermo Gonzalez-Rubio, Luis M. Liz-Marzan, Wiebke Albrecht, Sara Bals
Summary: Chirality in inorganic nanoparticles and nanostructures has attracted increasing scientific interest due to their ability to interact differently with circularly polarized light. Quantifying the degree of chirality in objects of nanoscale is challenging, but the authors introduce a methodology based on helical geometrical properties to quantify the helicity of complex chiral nanomaterials. They demonstrate that analyzing individual particles can provide significant insights into the origin of chiroptical properties.
ACS MATERIALS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Liang Yan, Manoj K. Jana, Peter C. Sercel, David B. Mitzi, Wei You
Summary: The study presents a new type of 2D hybrid perovskites with a unique combination of chirality and alkyl-aryl functionality, determined by noncovalent intermolecular interactions in their crystal structures. The mixed-cation perovskites exhibit a circular dichroism distinct from purely chiral cation analogues, providing a new avenue for tuning the chiroptical properties of known chiral perovskites. Mixing chiral cations with achiral cations may offer a potential way to tailor the spin-based properties in 2D hybrid perovskites.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Xichang Dong, Martin Klein, Siegfried R. Waldvogel, Bill Morandi
Summary: We report an electrochemistry enabled shuttle reaction (e-shuttle) to selectively transfer one RS- and one X- group between beta-halosulfides and unsaturated hydrocarbons. The high chemoselectivity of the process is controlled by the preferential anodic oxidation of one anion over the other based on their distinct redox potentials. This scalable methodology allows the construction of densely functionalized beta-halo alkenyl sulfides using benign surrogates, avoiding the use of corrosive and oxidative RS-Br reagents.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Martin Linden, Silja Hofmann, Antonia Herman, Nicole Ehler, Robin M. M. Baer, Siegfried R. R. Waldvogel
Summary: This study presents the first electrochemical approach for the direct synthesis of pyrazolines and pyrazoles from easily accessible hydrazones and dipolarophiles. The method allows for large-scale production and even conversion of highly sensitive alkenes. The use of a biphasic system with sodium iodide as a supporting electrolyte and mediator is cost-effective. Mechanistic insight is provided by the isolation of key intermediates, and the synthesis of a commercial herbicide safener further highlights the significance of this reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Johannes Winter, Tobias Prenzel, Tom Wirtanen, Dieter Schollmeyer, Siegfried R. R. Waldvogel
Summary: The use of electric current provides a sustainable and efficient method for the synthesis of quinoline N-oxides from readily available nitro compounds. The reaction employs mild and reagent-free conditions, and uses a simple undivided electrolysis cell with constant current set-up, leading to high conversion and atom economy. The synthesis of 30 differently substituted quinoline N-oxides was successfully achieved in up to 90% yield. Mechanistic insights were obtained through cyclic voltammetry studies, and the technical relevance of the reaction was demonstrated through a 50-fold scale-up.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Jana Klein, Siegfried R. R. Waldvogel
Summary: A sustainable electrochemical pathway for the degradation and thermal treatment of technical lignosulfonate is proposed. This method allows for the production of significant quantities of low molecular weight compounds, including vanillin and acetovanillone. The electrochemical degradation is carried out using a simple two-electrode setup in aqueous media, which can be easily scaled up. The biopolymer is oxidized at the anode, while hydrogen is evolved at the cathode. Subsequent thermal treatment further degrades the robust chemical structure of lignosulfonates. Under optimized electrolytic conditions, vanillin can be obtained in a yield of 9.7 wt% relative to the dry mass of lignosulfonate used. By-products such as acetovanillone or vanillic acid are also observed but in lower yields. Overall, this study establishes a new and reliable one-pot, two-step degradation process for various technically relevant lignosulfonates, offering the advantage of using electrons as an oxidizing agent and resulting in minimal reagent waste.
Article
Biochemistry & Molecular Biology
Lena Katharina Mueller-Heupt, Nadine Wiesmann-Imilowski, Sofia Schroeder, Jonathan Gross, Pablo Cores Ziskoven, Philipp Bani, Peer Wolfgang Kaemmerer, Eik Schiegnitz, Anja Eckelt, John Eckelt, Ulrike Ritz, Till Opatz, Bilal Al-Nawas, Christopher Synatschke, James Deschner
Summary: Periodontitis is a chronic inflammatory disease that leads to tooth loss and significantly impacts global health. A hyaluronic acid-based dispersion with controlled oxygen delivery shows potential as a treatment for periodontitis. In vitro and in vivo studies demonstrate the biocompatibility, antimicrobial activity against Porphyromonas gingivalis, and angiogenesis enhancement of the developed oxygen-releasing dispersion. This suggests the potential of oxygen-releasing biomaterials for periodontal tissue regeneration.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Applied
Camila M. Kisukuri, Johannes Seidler, Tobias Gartner, Denis F. Rohrmann, Siegfried R. Waldvogel
Summary: In this study, a robust and safe electrochemical method was developed for the synthesis of various 3-trifluoromethylanilines. The method can be scaled beyond the decagram scale and has significance in the pharmaceutical and agrochemical industry.
ORGANIC PROCESS RESEARCH & DEVELOPMENT
(2023)
Article
Chemistry, Multidisciplinary
Fiona Sprang, Jana Klein, Siegfried R. Waldvogel
Summary: A novel electrosynthetic protocol is reported for the direct conversion of 4-hydroxybenzaldehydes to valuable benzoquinones. The transformation is conducted through anodic oxidation, minimizing waste by eliminating terminal oxidants and redox mediators. Graphite serves as a metal-free anode material. A wide range of substituents, including halogens, are tolerated in this electrochemical protocol, with quinones selectively obtained in up to 99% yield. The compatibility of the protocol with electrochemical flow synthesis is demonstrated, and its application to lignosulfonate yields quinones in up to 7.6 wt%.
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2023)
Article
Infectious Diseases
Lena Katharina Mueller-Heupt, Anja Eckelt, John Eckelt, Jonathan Gross, Till Opatz, Nadine Kommerein
Summary: Periodontitis, caused by bacterial dysbiosis, is a common global disease associated with anaerobic bacterial colonization. A study investigated the potential of calcium peroxide (CaO2) as an antimicrobial agent for treating periodontitis. It was found that CaO2 selectively inhibited the growth and viability of Porphyromonas gingivalis but had little effect on Streptococcus oralis, indicating its potential for selectively affecting both planktonic bacteria and mono-species biofilms of P. gingivalis.
Article
Chemistry, Organic
Aaron Schuell, Lisa Grothe, Eduardo Rodrigo, Thomas Erhard, Siegfried R. Waldvogel
Summary: A novel electrosynthetic approach for the synthesis of aryl dibenzothiophenium salts, including the metal-free, electrochemical formation of a C-S bond under ambient conditions, has been reported. The broad applicability of this method has been demonstrated with 14 examples, achieving isolated yields of up to 72%, including nitrogen-containing heterocycles. The resulting sulfonium salts can serve as precursors for the synthesis of [F-18]fluoroarenes found in PET tracer ligands.
Article
Chemistry, Applied
Tobias Lucas, Jule-Philipp Dietz, Flavio S. P. Cardoso, David R. Snead, Ryan C. Nelson, Kai O. Donsbach, B. Frank Gupton, Till Opatz
Summary: An efficient gram-scale synthesis of the antituberculosis agent pretomanid was achieved using straightforward chemistry, mild reaction conditions, and readily available starting materials. The synthesis involved investigating different protecting groups on the glycidol moiety and utilized a linear three-step process with up to 40% isolated yield. Notably, the deprotection and cyclization steps were performed in a one-pot fashion without the need for hazardous materials or steps.
ORGANIC PROCESS RESEARCH & DEVELOPMENT
(2023)
Article
Chemistry, Applied
Roland J. -R. Bednarz, Annika S. S. Gold, Jasmin Hammes, Denis F. F. Rohrmann, Silvio Natalello, Moritz Mann, Frank Weinelt, Christopher Brauer, Siegfried R. R. Waldvogel
Summary: The rapidly advancing climate change necessitates the development of more sustainable synthetic pathways for critical chemicals, such as adipic acid or its derivatives. In this study, 3-ethyladipic acid was synthesized through an environmentally benign electrochemical method using 4-ethylcyclohexanol as the precursor, derived from lignin. The production rate of the target compound was significantly enhanced in a scaled and commercially available flow electrolyzer with an increased anodic surface area.
ORGANIC PROCESS RESEARCH & DEVELOPMENT
(2023)
Article
Multidisciplinary Sciences
Joachim Nikl, Kamil Hofman, Samuel Mossazghi, Isabel C. Moeller, Daniel Mondeshki, Frank Weinelt, Franz-Erich Baumann, Siegfried R. Waldvogel
Summary: A general electrochemical method is presented for the oxidation of C(sp(3))-H and C(sp(2))-H bonds, using nitrate salts as both anodic mediator and supporting electrolyte. This method allows the conversion of cyclic alkanes and alkenes into cycloaliphatic ketones and aliphatic dicarboxylic acids. It represents a sustainable oxo-functionalization method by avoiding transition metals and chemical oxidizers.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Martin Linden, Silja Hofmann, Felix N. Weber, Robin M. Baer, Sherif J. Kaldas, Mark J. Ford, Siegfried R. Waldvogel
Summary: To demonstrate the technical application potential of electrochemical reactions, we developed a synthetic method to access the commercially available herbicide safener mefenpyr-diethyl. The target compound was synthesized via the (E)- or (Z)-hydrazone in a simple undivided electrolysis cell with non-hazardous aqueous sodium iodide as supporting electrolyte and mediator. Environmentally benign solvents or solvent-free conditions ensure a sustainable process and excellent recycling of the excess reagents. Finally, scale-up to the hectogram scale was performed with good to excellent yield.
Article
Chemistry, Organic
Silja Hofmann, Martin Linden, Julian Neuner, Felix N. Weber, Siegfried R. Waldvogel
Summary: This article presents an electrochemically enabled approach for the sustainable synthesis of pyrazoles via oxidative aromatization of pyrazolines. It utilizes inexpensive sodium chloride as a redox mediator and supporting electrolyte in a biphasic system (aqueous/organic), and can be conducted using carbon-based electrodes in a simple electrolysis set-up. The method allows for simple work-up strategies such as extraction and crystallization, enabling its application on a technically relevant scale.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Olesja Koleda, Tobias Prenzel, Johannes Winter, Tomoki Hirohata, Maria de Jesus Galvez-Vazquez, Dieter Schollmeyer, Shinsuke Inagi, Edgars Suna, Siegfried R. Waldvogel
Summary: Cathodic synthesis enables the sustainable access to 1-hydroxy- and 1-oxy-quinazolin-4-ones utilizing easily accessible nitro starting materials. This method features mild reaction conditions, inexpensive and reusable carbon-based electrode materials, an undivided electrochemical setup, and constant current conditions. The use of sulphuric acid as a supporting electrolyte and cyclization catalyst, along with the broad applicability demonstrated with 27 differently substituted derivatives achieving high yields (up to 92%), emphasizes its significance for preparative applications. Mechanistic studies based on cyclic voltammetry measurements reveal the selective reduction of nitro substrates to hydroxylamines as a crucial step.
