Review
Chemistry, Multidisciplinary
Si -hua Liu, Hong Wang, Jian-ke Sun, Markus Antonietti, Jiayin Yuan
Summary: This article presents the recent progress and applications of 1,2,4-triazolium-type poly(ionic liquid)s (SHAs). SHAs enhance performance profiles through the formation of smart hydrogen atoms and can be used for materials design at the nano-, micro-, and macroscopic scales. At the nano scale, SHAs can manipulate the shape and surface properties of nanocolloids. At the micro and macro scales, SHAs catalyze single crystal formation of structurally complex organics and enable the fabrication of functional supramolecular porous polyelectrolyte membranes.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Review
Chemistry, Multidisciplinary
Si-hua Liu, Hong Wang, Jian-ke Sun, Markus Antonietti, Jiayin Yuan
Summary: The search for molecular functionality platforms for materials chemistry innovation is a key goal, with Poly(ionic liquid)s (PILs) serving as a bridge between multiple research areas and offering new chemical tools and opportunities for material design. The smart hydrogen atoms (SHAs) in 1,2,4-triazolium-type PILs show enhanced performance profiles, providing possibilities for novel materials applications.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Article
Chemistry, Multidisciplinary
Zi-Jing Zhang, Yu-Hua Wen, Jin Song, Liu-Zhu Gong
Summary: The study developed an efficient KR and DyKAT method using N-heterocyclic carbene (NHC)/copper cooperative catalysis, resulting in highly enantioenriched derivatives and products with high structural diversity. Mechanistic studies indicated that NHC can regulate the catalytic activity of the copper catalyst, enabling the switch of chemical selectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Jian Zhang, Yan-Shan Gao, Bu-Ming Gu, Wu-Lin Yang, Bo-Xue Tian, Wei-Ping Deng
Summary: A cooperative NHC/iridium catalysis has been developed for stereo-selective and regiodivergent annulation reactions of 2-indolyl allyl carbonates with enals, yielding biologically important products with high selectivity. By permutations of the enantiomers of the two chiral catalysts, all four stereoisomers of the products with vicinal stereocenters can be obtained.
Article
Chemistry, Multidisciplinary
David Specklin, Christophe Fliedel, Samuel Dagorne
Summary: This review discusses the recent advancements in the synthesis, structure, and catalytic applications of Zn-NHC species, which have gained attention for their enhanced stability and hydrolytic stability compared to traditional Zn organometallics. NHC stabilization has enabled access to unprecedented Zn species, leading to effective catalysis under mild conditions. The potential of NHC-Zn species for stabilizing novel Zn species and their use in various catalytic applications is still emerging, with a wide range of NHC structures available to promote future developments in the field.
Article
Chemistry, Multidisciplinary
Yuan-Yuan Xu, Zhong-Hua Gao, Cao-Bo Li, Song Ye
Summary: The enantioselective alpha-oxidative coupling of enals with carboxylic acids was achieved by umpolung of an NHC-bound enolate with an iodine(III) reagent. The reaction produced alpha-acyloxyl-beta,gamma-unsaturated esters in good yields, with high regio- and enantioselectivities. The reaction involved the formation of an enol iodine(III) intermediate from the enolate with iodosobenzene, which changed the polarity of the enal's alpha-carbon from nucleophilic to electrophilic and facilitated the subsequent carboxylate addition.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Bastiaan Kooij, Zhaowen Dong, Paul Varava, Farzaneh Fadaei-Tirani, Rosario Scopelliti, Laura Piveteau, Kay Severin
Summary: This study reports the preparation and structural characterization of vanadium complexes with N-heterocyclic vinylidene ligands, enabled by utilizing diazoolefins as ligand precursors. Structural and theoretical analysis show that N-heterocyclic vinylidenes can act as strong 6e(-) donor ligands, forming strong metal-carbon interactions.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Changhang Dai, Matthew Chapman, Masayuki Wasa
Summary: We propose a method for the combination of N-allylamines and carbonyl compounds through the concerted action of B(C6F5)(3) and a N-based Bronsted base under redox-neutral conditions. By the reaction of in situ generated conjugated iminium ions and enolates, & delta;-aminocarbonyl compounds are obtained without waste generation. Furthermore, the cooperative action of B(C6F5)(3), a chiral Zn-based complex, and an amine enables the stereoselective reaction of a glycinate Schiff base ester and an N-allylamine to yield an & alpha;-substituted & alpha;-amino ester.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Zheng-Wang Qu, Hui Zhu, Rainer Streubel, Stefan Grimme
Summary: Extensive DFT calculations in this study show that the isomerization of unprotected C-5-position mesoionic N-heterocyclic olefins (mNHOs) can be efficiently catalyzed by weakly protic acidic species, including mNHOs themselves, their Lewis adducts, and polar H2O molecules, leading to the formation of more Lewis-basic mesoionic carbenes (MICs) and enabling catalytic isomerization and H-isotope exchange of mNHOs and their Lewis adducts.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Hyunho Kim, Minseop Kim, Hayoung Song, Eunsung Lee
Summary: The synthesis of ambiphilic N-heterocyclic carbene ligand indol-2-ylidene (IdY, A) was described, along with its ambiphilicity and synthetic utility. Experimental and computational studies showed that IdY lies between CAAC-5 and CAArC, with copper complexes capable of carboboration of terminal alkynes with high regioselectivity and good yields within 30 minutes.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Wacharee Harnying, Panyapon Sudkaow, Animesh Biswas, Albrecht Berkessel
Summary: Simple carboxylic acids, like benzoic acid, have been found to enhance the activity of N-heterocyclic carbene (NHC) catalysts in the oxidative esterification of aldehydes. A protocol using a novel N-Mes-/N-2,4,6-trichlorophenyl 1,2,4-triazolium salt as catalyst and benzoic acid as co-catalyst was developed for the transformation of a wide range of sterically hindered alpha- and beta-substituted aliphatic aldehydes/enals. The observed effect is believed to be due to the carboxylic acid-induced acceleration of acyl transfer from azolium enolate intermediates.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Ningwei Sun, Shi-Tong Zhang, Frank Simon, Anja Maria Steiner, Jonas Schubert, Yixuan Du, Zhi Qiao, Andreas Fery, Franziska Lissel
Summary: By using N-heterocyclic carbenes (NHCs) as anchor groups, organic ligands can be bound to colloidal gold, resulting in the successful preparation of P3HTs-NHC-Au with narrow molecular weight distributions. These gold nanoparticles exhibit excellent thermal and redox stability.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Luis Werner, Julika Hagn, Janis Walpuski, Udo Radius
Summary: This study synthesized aminoborate complexes using N-heterocyclic carbene ligands and assessed their potential applications in catalytic CO2 conversion.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Lenka Pallova, Laura Abella, Marion Jean, Nicolas Vanthuyne, Cecile Barthes, Laure Vendier, Jochen Autschbach, Jeanne Crassous, Stephanie Bastin, Vincent Cesar
Summary: The first efficient chiral helicene-NHC gold(I) complexes for enantioselective catalysis have been synthesized. Their structural and stereochemical characterization confirms their potential in asymmetric catalysis, demonstrated by the benchmark cycloisomerization reaction with high enantiomeric excess.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Xiaoye Yu, Anirban Maity, Armido Studer
Summary: An alternative disconnection approach using aroyl fluorides as bifunctional reagents for fluoroaroylation of gem-difluoroalkenes through cooperative photoredox and N-heterocyclic carbene (NHC) catalysis is reported. This strategy enables the synthesis of alpha-CF3-substituted ketones efficiently and without the use of expensive or sensitive reagents and the requirement for ketone pre-functionalization. The methodology also allows rapid access to mono- or difluoroalkyl ketones.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Polymer Science
Hande Acikalin, Pradeep K. R. Panyam, Abdul Wasif Shaikh, Dongren Wang, Shravan R. Kousik, Petia Atanasova, Michael R. Buchmeiser
Summary: Non-porous polyurethane-based monoliths with low specific surface areas and pore volumes are prepared under solvent-induced phase separation conditions. Mesoporosity can be introduced by varying the monomers and solvents. The monoliths are functionalized with quaternary ammonium groups and used to immobilize an ionic liquid containing an ionic Rh-catalyst for hydrosilylation reactions. The confined small mesopores contribute to the significant increase in Z-selectivity.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2023)
Article
Chemistry, Inorganic & Nuclear
Janis V. V. Musso, Vincent Gramm, Sarjano Stein, Wolfgang Frey, Michael R. R. Buchmeiser
Summary: A series of molybdenum alkylidyne silyloxy N-heterocyclic carbene complexes were synthesized, and the study found that the air stability of the complexes in the solid-state increased with the increasing steric demand of the alkylidyne group. The most stable complex could remain stable in air for 24 hours without showing signs of decomposition.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Polymer Science
Michael R. Buchmeiser, Patrick Probst, Dongren Wang, Philipp Hauser
Summary: A series of cationic tungsten sulfido alkylidene N-heterocyclic carbene complexes were used as initiators in ROMP, achieving high stereocontrol and varying percentages of syndiotactic sequences. Mechanistic investigations suggest that the unique reactivity of the initiators contributes to the predominant trans-isospecifity observed in the polymerization.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2023)
Article
Energy & Fuels
Martha L. Chacon-Patino, Anika Neumann, Christopher P. Ruger, Paolo G. Bomben, Lukas Friederici, Ralf Zimmermann, Erik Frank, Philipp Kreis, Michael R. . Buchmeiser, Murray R. Gray
Summary: Asphaltenes derived from bitumen can be used as potential feedstocks for stable carbon fiber production after upgrading processes to adjust their rheological properties.
Article
Chemistry, Inorganic & Nuclear
Michael R. Buchmeiser, Dominik Imbrich, Dongren Wang, Stefan Naumann
Summary: The authors synthesized a series of tungsten (VI) imido alkylidene N-heterocyclic olefin (NHO) complexes and found that the catalysts showed improved activity in ring-closing metathesis by adjusting the number and type of NHO ligands. The results indicate that further optimization of the catalysts' performance can be achieved by ligand tuning.
JOURNAL OF ORGANOMETALLIC CHEMISTRY
(2023)
Article
Polymer Science
Janis V. Musso, Paul Gebel, Vincent Gramm, Wolfgang Frey, Michael R. Buchmeiser
Summary: A system for visible-light-controlled ring-opening metathesis polymerization (ROMP) was developed by combining thermally latent group 6 olefin metathesis initiators with a photoredox catalyst. This system can be applied to two-dimensional (2D) photolithography, and it exhibits high activity and stability without the need for thermal or UV post-curing.
Article
Polymer Science
Klaus Heudorfer, Johannes Bauer, Yavuz Caydamli, Bruno Gompf, Jens Take, Michael R. Buchmeiser, Peter Middendorf
Summary: Recently, fiber-reinforced, epoxy-based, optically transparent composites were successfully produced using resin transfer molding (RTM) techniques. A new mold design was described, and three plates of optically transparent glass fiber-reinforced polymers (tGFRP) were produced with reproducible properties and high fiber volume fractions. The research found improved surface quality and good transmission data for samples manufactured by a new Optical-RTM setup.
Article
Chemistry, Physical
Felix Ziegler, Johanna R. Bruckner, Michal Nowakowski, Matthias Bauer, Patrick Probst, Boshra Atwi, Michael R. Buchmeiser
Summary: The immobilization of tungsten-based catalysts inside ordered mesoporous silica results in enhanced macrocyclization and Z-selectivity, allowing high substrate concentrations. Smaller mesopores exhibit a stronger confinement effect. The two supported catalysts show different selectivities, which can be rationalized by their structures.
Article
Chemistry, Multidisciplinary
Koushani Kundu, Janis V. Musso, Mathis J. Benedikter, Wolfgang Frey, Katrin Gugeler, Johannes Kaestner, Michael R. Buchmeiser
Summary: Neutral and cationic Mo imido alkylidene CAAC complexes were synthesized and their synthetic peculiarities were investigated. Due to the Σ-donor/π-acceptor characteristics of CAACs, stabilizing donor ligands like nitriles were not required for these complexes. Selected complexes were characterized by single-crystal X-ray analysis. All cationic complexes showed higher activity compared to analogous NHC complexes in olefin metathesis reactions, with turnover numbers (TONs) up to 9500 even at room temperature. Some Mo imido alkylidene CAAC complexes exhibited tolerance towards functional groups like thioethers and sulfonamides.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Philipp Kreis, Erik Frank, Bernd Clauss, Volker Bauch, Heiko Stolpmann, Lisa Kuske, Tanja Schneck, Simon Koenig, Michael R. Buchmeiser
Summary: This study reports the preparation of lignin-based carbon fibers by dry spinning from aqueous solution, followed by stabilization and continuous carbonization to endless yarns. The effects of carbonization temperature and draw ratio on the morphology and mechanical properties of the final carbon fibers were investigated. The study found that a draw ratio of 5% (1.05) and a carbonization temperature of 1400 degrees C resulted in the best mechanical properties of the carbon fibers.
MACROMOLECULAR MATERIALS AND ENGINEERING
(2023)
Article
Chemistry, Inorganic & Nuclear
Laura Stohr, Christian Fajman, Roman Schowner, Iris Elser, Andreas Fuchs, Philipp M. Hauser, Somnath Bhattacharya, Dongren Wang, Michael R. Buchmeiser
Summary: This study determined the interconversion rates of the syn- and anti-isomers of neutral molybdenum and tungsten imido alkylidene N-heterocyclic carbene complexes and found that they were significantly lower than in tetracoordinated Schrock catalysts. NMR investigations suggest that higher transition state Gibbs free energy values are due to the dissociation of an anionic ligand from a neutral pentacoordinated catalyst. The anti-isomer showed higher reactivity and productivity in both ring-opening metathesis polymerization and ring-closing metathesis reactions.
Article
Chemistry, Physical
Pradeep K. R. Panyam, Michael R. Buchmeiser
Summary: Polymeric mesoporous monoliths were prepared via ring-opening metathesis polymerization (ROMP) and surface grafted with 1-(2-((norborn-5-ene-2-carbonyl)oxy)ethyl)-3-ethyl-1H-imidazol-3-ium tetrafluoroborate. A supported ionic-liquid-phase (SILP) system was created by immobilizing the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] with the cationic catalyst [Rh((1-pyrid-1-yl)-3-mesitylimidazol-2-ylidene)(COD)+BF4-]. The hydrosilylation reaction using Rh@SILPROMP showed higher beta-(Z) selectivity and no metal leaching compared to Rh-1 under biphasic conditions.
FARADAY DISCUSSIONS
(2023)
Review
Polymer Science
Stefan Naumann
Summary: Since 2016, there has been an increased interest in the use of simple triethylborane (Et3B) as a catalyst for the copolymerization of epoxides and carbon dioxide. This catalyst has demonstrated improved functional group tolerance, polymerization control, and practical aspects such as low catalyst loadings and metal-free setups. These advancements have allowed for more precise synthesis of polyethers, complex architectures, and epoxide-based copolymers, leading to extended and novel applications in various fields. This review highlights the catalytic performance of Et3B, strategies for catalyst design, and their impact on polymer properties.
Article
Electrochemistry
Julian Kappler, Sina V. Klostermann, Pia L. Lange, Michael Dyballa, Lothar Veith, Thomas Schleid, Tanja Weil, Johannes Kaestner, Michael R. Buchmeiser
Summary: This study compares sulfur/polymer composites derived from nitrogen-containing poly(acrylonitrile) (PAN) and nitrogen-free poly(vinylacetylene) (PVac). Results indicate the importance of a nitrogen-rich, aromatic carbon backbone for full addressability of polymer-bound sulfur and its reversible binding to the aromatic backbone, even at high current rates.
BATTERIES & SUPERCAPS
(2023)
Article
Chemistry, Multidisciplinary
Ayla Sirin-Sariaslan, Stefan Naumann
Summary: This article presents chiral diborane polymerization catalysts with 3,30-disubstituted binaphthol-backbones. These compounds deliver isotactic poly(propylene oxide) with high isotactic diad (m) and triad (mm) placements of up to 92% and 480%, respectively, from racemic monomer.
CHEMICAL COMMUNICATIONS
(2023)