Lionel Wettstein

Last Name

Wettstein

First Name

Lionel

ORCID

0000-0002-0579-1177

Organisational unit

09759 - Bezdek, Máté József / Bezdek, Máté József

Show all metadata

Search Results

Publications 1 - 8 of 8

Dynamic dimer–monomer equilibrium in a cycloruthenated complex of [Re(η6-C6H6)2]+
Hernández-Valdés, Daniel; Wettstein, Lionel; Fernández-Terán, Ricardo; et al. (2020)
Chemical Communications
Cycloruthenation is a well known process in organometallic ruthenium chemistry. In this work, we report unprecedented cycloruthenated rhenium bis-arene compounds with planar chirality. In a two-step process, the reaction of acetyl-pyridine with [Re(η6-C6H6)2]+ introduced a pyridinyl-methanol ligand at one of the arene rings. Coordination of [Ru(CO)2Cl2] led to cycloruthenation, and the products were obtained as two diastereomeric pairs of enantiomers. Under basic pH conditions, the two pairs of enantiomers undergo spontaneous and reversible dimerization. The cycloruthenated monomers were fully characterized, and the dimerization process was studied by NMR, IR spectroscopy, and DFT calculations.
Examining Trichloroisocyanuric Acid and Oxalyl Chloride in Complementary Approaches to Fluorination of Group 15 Heteroatoms
Bornemann, Dustin; Brüning, Fabian; Bartalucci, Niccolo; et al. (2021)
Helvetica Chimica Acta
A mild, oxidative fluorination approach to a variety of fluorinated phosphorus compounds using trichloroisocyanuric acid (TCICA) and KF was developed as a complement to a recent study on deoxygenative fluorination using oxalyl chloride. Herein, the syntheses of several fluorinated organophosphorus compounds are reported, and both TCICA/KF and oxalyl chloride/KF conditions are compared and contrasted throughout. Initial investigations of the method on other group 15 heteroatoms (i. e., As, Sb, and Bi) are also reported, with varied success. This work notably extends the known TCICA/KF reactivity series to another group of elements beyond previously studied chalcogens (S, Se, and Te) and halogens (iodine) and expands the utility of the previously reported oxalyl chloride/KF method.
Phosphine Oxide‐Functionalized Terthiophene Redox Systems
Käch, Daniel; Gasser, Aurelio C.; Wettstein, Lionel; et al. (2023)
Angewandte Chemie. International Edition
Main group systems capable of undergoing controlled redox events at extreme potentials are elusive yet highly desirable for a range of organic electronics applications including use as energy storage media. Herein we describe phosphine oxide-functionalized terthiophenes that exhibit two reversible 1e− reductions at potentials below −2 V vs Fc/Fc+ (Fc=ferrocene) while retaining high degrees of stability. A phosphine oxide-functionalized terthiophene radical anion was synthesized in which the redox-responsive nature of the platform was established using combined structural, spectroscopic, and computational characterization. Straightforward structural modification led to the identification of a derivative that exhibits exceptional stability during bulk 2 e− galvanostatic charge–discharge cycling and enabled characterization of a 2 e− redox series. A new multi-electron redox system class is hence disclosed that expands the electrochemical cell potential range achievable with main group electrolytes without compromising stability.
Deoxygenative Fluorination of Phosphine Oxides: A General Route to Fluorinated Organophosphorus(V) Compounds and Beyond
Bornemann, Dustin; Pitts, Cody R.; Wettstein, Lionel; et al. (2020)
Angewandte Chemie. International Edition
Fluorinated organophosphorus(V) compounds are a very versatile class of compounds, but the synthetic methods available to make them bear the disadvantages of 1) occasional handling of toxic or pyrophoric P(III)starting materials and 2) a dependence on hazardous fluorinating reagents such as XeF2. Herein, we present a simple solution and introduce a deoxygenative fluorination (DOF) approach that utilizes easy-to-handle phosphine oxides as starting materials and effectively replaces harsh fluorinating reagents by a combination of oxalyl chloride and potassium fluoride. The reaction has proven to be general, as R3PF2, R2PF3, and RPF(4)compounds (as well as various cations and anions derived from these) are accessible in good yields and on up to a multi-gram scale. DFT calculations were used to bolster our observations. Notably, the discovery of this new method led to a convenient synthesis of 1) new difluorophosphonium ions, 2) hexafluorophosphate salts, and 3) fluorinated antimony- and arsenic- compounds.
A Dye-Sensitized Sensor for Oxygen Detection under Visible Light
Wettstein, Lionel; Specht, Julia; Kesselring, Vera; et al. (2024)
Advanced Science
Sensors that can accurately assess oxygen (O2) concentrations in real time are crucial for a wide range of applications spanning personal health monitoring, environmental protection, and industrial process development. Here a high-performance chemiresistive sensor that allows for the rapid detection of O2 at room temperature under visible light illumination is described. Inspired by the operating principles of dye-sensitized solar cells, the chemiresistor is based on a single-walled carbon nanotube-titania hybrid (SWCNT-TiO2) bearing a molecular Re-based photosensitizer [(Pbpy)(CO)3ReBr] (Pbpy = 4,4 '-[P(O)(OH)2]2-2,2 '-bipyridine). The resulting SWCNT-TiO2-Re composite undergoes photoinduced charge transfer that is sensitive to ppb levels of O2, thereby yielding a rapid and reversible chemiresistive response. Owing to its unique mode of operation and robust components, the sensor shows a high degree of selectivity for O2 over a range of interferants, humidity tolerance, and multimonth benchtop stability. The approach presented herein demonstrates the translatability of concepts in light harvesting to the development of robust, rapid, and low-power sensing technologies.
Triphenylphosphine Oxide: A Versatile Covalent Functionality for Carbon Nanotubes
Pan, Yanlin; Baster, Dominika; Kach, Daniel; et al. (2024)
Angewandte Chemie. International Edition
Broadening the scope of functionalities that can be covalently bound to single-walled carbon nanotubes (SWCNTs) is crucial for enhancing the versatility of this promising nanomaterial class in applied settings. Here we report the covalent linkage of triphenylphosphine oxide [Ph₃P(O)] to SWCNTs, a hitherto overlooked surface functionality. We detail the synthesis and structural characterization of a new family of phosphine oxide-functionalized diaryliodonium salts that can facilitate direct Ph₃P(O) transfer and afford novel SWCNTs with tunable Ph₃P(O) content (SWCNT-P). The molecularly-distributed and robust nature of the covalent Ph₃P(O) attachment in SWCNT-P was supported by a combination of characterization methods including Raman, infrared, UV/Vis-NIR and X-ray photoelectron spectroscopies coupled with thermogravimetric analysis. Electron microscopy further revealed the effectiveness of the Ph₃P(O) moiety for de-bundling SWCNTs to yield SWCNT-P with superior dispersibility and processability. Finally, electrochemical studies established that SWCNT-P is sensitive to the presence of Li⁺, Na⁺ and K⁺ wherein the Gutmann-Beckett Lewis acidity parameters of the ions were quantitatively transduced by Ph₃P(O) to electrochemical responses. This work hence presents a synthetic, structural, spectroscopic and electrochemical foundation for a new phosphorus-enriched responsive nanomaterial platform featuring the Ph₃P(O) functionality.
Desoxyfluorierung von Phosphanoxiden: Ein allgemeiner Weg zu fluorierten Organophosphor(V)‐Verbindungen und noch mehr
Bornemann, Dustin; Pitts, Cody R.; Wettstein, Lionel; et al. (2020)
Angewandte Chemie
Fluorierte Organophosphor(V)‐Spezies sind eine vielseitige Klasse von Verbindungen. Ihre aktuell zur Verfügung stehenden Synthesemethoden haben jedoch die Nachteile der gelegentlichen Handhabung von toxischen oder pyrophoren PIII‐Ausgangsmaterialien und der Abhängigkeit von gefährlichen Fluorierungsreagenzien wie XeF2. Wir präsentieren hier eine alternative Methode zur Lösung dieser Probleme mittels Desoxyfluorierung (DOF) von einfach zu gebrauchenden Phosphanoxiden als Ausgangsmaterialien und vermeiden gleichzeitig aggressive Fluorierungsreagenzien durch eine Kombination von Oxalylchlorid und Kaliumfluorid. Die Reaktion hat sich als allgemein anwendbar erwiesen, da R3PF2‐, R2PF3‐ und RPF4‐Verbindungen (sowie verschiedene davon abgeleitete Kationen und Anionen) in guten Ausbeuten und im Multi‐Gramm‐Maßstab zugänglich sind. DFT‐Berechnungen wurden verwendet, um unsere Beobachtungen zu untermauern. Insbesondere führte die Entdeckung dieser neuen Methode zu einer bequemen Synthese von 1) neuen Difluorphosphoniumionen, 2) Hexafluorphosphatsalzen und 3) fluorierten Antimon‐ und Arsenverbindungen.
Functionalized Terthiophene as an Ambipolar Redox System: Structure, Spectroscopy, and Switchable Proton-Coupled Electron Transfer
Käch, Daniel; Klose, Daniel; Wettstein, Lionel; et al. (2025)
Journal of the American Chemical Society
Organic redox systems that can undergo oxidative and reductive (ambipolar) electron transfer are elusive yet attractive for applications across synthetic chemistry and energy science. Specifically, the use of ambipolar redox systems in proton-coupled electron transfer (PCET) reactions is largely unexplored but could enable "switchable" reactivity wherein the uptake and release of hydrogen atoms are controlled using a redox stimulus. Here, we describe the synthesis and characterization of an ambipolar functionalized terthiophene (TTH) bearing methyl thioether and phosphine oxide groups that exhibits switchable PCET reactivity. Electrochemical studies established that the functionalized TTH can be reversibly oxidized and reduced, prompting the synthesis and characterization of cationic and anionic radicals on a single TTH platform. Combined structural, spectroscopic, and computational investigations revealed the influence of the methyl thioether and phosphine oxide moieties on the TTH electronic structure that results in the stabilization of both cationic and anionic radicals. Upon single-electron oxidation, the functionalized TTH serves as a hydrogen atom acceptor and undergoes PCET with 1,4-dihydroquinone to generate a TTH hydroxyphosphonium species. The process was found to be reversible upon single-electron reduction, with functionalized TTH acting as a hydrogen atom donor in a PCET reaction with 2,3-dimethylanthraquinone. The thermochemistry of the O-H bond formed and cleaved in functionalized TTH during the reaction sequence was investigated, revealing that a bond weakening of 30 kcal/mol underpins the switchable PCET reactivity. Overall, these studies provide an electrochemical, structural, spectroscopic, and thermochemical foundation for the use of ambipolarity to control PCET reactions in organic redox systems.

Publications 1 - 8 of 8

Lionel Wettstein

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results