Review
Chemistry, Multidisciplinary
Yong Xia, Xiaohua Liu, Xiaoming Feng
Summary: The donor-acceptor (D-A) cyclopropanes, due to the synergistic push-pull effect of vicinal electron-donating and electron-withdrawing groups, are recognized as powerful building blocks for generating polyfunctional reactive intermediates. Enantioselective reactions of D-A cyclopropanes provide an efficient approach to enantioenriched acyclic and cyclic compounds. Chiral Lewis/Bronsted acids, transition metals, and organocatalysts have been designed for such transformations, including ring-openings, annulations, and rearrangements.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Nils L. Ahlburg, Oliver Hergert, Peter G. Jones, Daniel B. Werz
Summary: A novel class of highly activated donor-acceptor cyclopropanes with a single vinylogous acceptor is presented. These moieties undergo cycloaddition reactions with various substrates to form carbo- and heterocycles. The stereochemical outcome can be controlled by the choice of catalyst. Mechanistic and kinetic experiments were conducted to explain the catalytic cycle and stereoselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Stefano Nicolai, Jerome Waser
Summary: This study reports a Lewis acid catalyzed (4+3) annulative addition reaction for the efficient synthesis of densely substituted azepanes. The reaction achieved good yields and high diastereoselectivity under mild conditions using ytterbium triflate or copper triflate with a trisoxazoline ligand as the catalyst. The obtained cycloadducts were convenient substrates for further modifications.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
David A. McLeod, Mathias Kirk Thogersen, Casper Larsen Barlose, Mette Louise Skipper, Erlaitz Basabe Obregon, Karl Anker Jorgensen
Summary: This study presents a novel enantioselective (8+3) cycloaddition reaction using a chiral bifunctional Bronsted base catalyst. The reaction leverages an anionic activation strategy and differs from typical Lewis-acid activation protocols. Experimental and computational results support the relevance of this reaction and its potential application in organic synthesis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Ming Bao, Karlos Lopez, Raj Gurung, Hadi Arman, Michael P. Doyle
Summary: A highly enantioselective synthesis of chiral dihydro-3H-carbazole-2-carboxylate derivatives is achieved via a one-pot cascade reaction catalyzed by nickel(II) perchlorate hexahydrate and scandium(III) trifluoromethanesulfonate. The reaction proceeds under mild conditions and provides the desired products in high yields and enantioretention. Furthermore, these dihydro-3H-carbazole-2-carboxylates can be transformed into decarboxylated compounds through hydrolysis and decarboxylation under unexpectedly mild reaction conditions, giving moderate yields with high retention of enantiomeric purity.
Article
Chemistry, Multidisciplinary
Monika M. Lindner, M. Wasim Alachraf, Benjamin Mitschke, Philipp Schulze, Markus Leutzsch, Benjamin List
Summary: A method for converting aldehydes into arenes is designed, involving the reaction of aldehydes to form fulvenes, followed by photochemical and platinum-catalyzed rearrangements into Dewar benzene derivatives, which finally isomerize into the desired arenes. Computational studies support the feasibility of this route, but fulvene irradiation unexpectedly results in isomerization into spiro[2.4]heptadienes. The mechanistic investigation of this unusual photorearrangement provides access to various spiro[2.4]heptadienes with different substituents.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Shiksha Deswal, Avishek Guin, Akkattu T. Biju
Summary: The use of benzotriazoles as nucleophilic triggers in the three-component Yb(OTf)(3)-catalyzed ring-opening 1,3-aminofunctionalization of donor-acceptor (D-A) cyclopropanes is described. The reaction yields 1,3-aminohalogenation products in up to 84% yield when N-halo succinimide (NXS) is used as the third component. Alkyl halides or Michael acceptors as the third components lead to the formation of 3,1-carboaminated products in up to 96% yield in a one-pot operation. Using Selectfluor as the electrophile, the reaction affords 1,3-aminofluorinated products in a 61% yield.
Article
Chemistry, Physical
Ming Bao, Karlos Lopez, Raj Gurung, Hadi Arman, Michael P. Doyle
Summary: A highly enantioselective synthesis of chiral dihydro-3H-carbazole-2-carboxylate derivatives is achieved via a one-pot cyclopentannulation-rearrangement cascade reaction. The reaction is catalyzed by nickel(II) perchlorate hexahydrate and scandium(III) trifluoromethanesulfonate, and involves the use of 3-methylindole and non-racemic donor-acceptor cyclopropanes. The resulting products show high yields and enantioretention under mild reaction conditions, and further transformation into decarboxylated compounds can be achieved with moderate yields and high enantiomeric purity.
Article
Materials Science, Multidisciplinary
P. J. Jumana, A. Anil, V Kumar
Summary: This study reports the possibility of using defect chemistry to suppress hexagonal phase formation in donor-acceptor co-doped BaTiO3 for the first time. The stabilization of the perovskite phase is related to the donor/acceptor ratio and the doping mechanism.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Chemistry, Multidisciplinary
Meifeng Hou, Jiajun Li, Fucai Rao, Zuliang Chen, Yingjing Wei
Summary: In this study, the construction of N-heterocyclic eight-membered rings using Lu(OTf)(3) as a catalyst is reported. A formal [4+4] cycloaddition reaction of cyclobutane 1,1-diesters with anthranils was used to deliver oxa-bridged eight-membered heterocycles, providing a potential method for building complex azocine compounds.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Gwyndaf A. Oliver, Maximilian N. Loch, Andre U. Augustin, Pit Steinbach, Mohammed Sharique, Uttam K. Tambar, Peter G. Jones, Christoph Bannwarth, Daniel B. Werz
Summary: The paper presents rare examples of cycloadditions involving D-A cyclopropanes and cyclobutanes with N-sulfinylamines and a sulfur diimide, leading to the formation of five- and six-membered rings containing adjacent heteroatoms. A one-pot, two-step strategy is introduced for the formal insertion of HNSO2 into D-A cyclopropanes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Polymer Science
Alexis Emmerich, Constantin C. Daniliuc, Armido Studer
Summary: The stereospecific ionic ring-opening polymerization of various donor-acceptor cyclopropanes allows for the preparation of chiral polymers, with the potential for diverse applications by adjusting the substituents of the monomers.
MACROMOLECULAR RAPID COMMUNICATIONS
(2021)
Article
Chemistry, Organic
Kanyashree Jana, Debarghya Sarkar, Preeti Jaiswal, Jarugu Narasimha Moorthy
Summary: A set of donor-acceptor azahelical coumarins (DA-AHCs) with high fluorosolvatochromic shifts and high quantum yields in solution and solid states were designed and synthesized. The excited-state properties of these compounds were investigated, revealing the contribution of intramolecular charge transfer and crystal packing to their emission behaviors. The analysis showed that strengthened hydrogen bonding promoted quenching, efficient crystal packing promoted high emission, and loose crystal packing contributed to excited-state deactivation.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Electrochemistry
Sandra Pluczyk-Malek, Damian Honisz, Alexander Akkuratov, Pavel Troshin, Mieczyslaw Lapkowski
Summary: Two molecules with D-A(2)-A(1)-A(2)-D structure, named QXBT and BXBT, were synthesized and characterized using various techniques. Changing the A(2) acceptor unit was found to tune the conjugation of molecules and affect both reduction and oxidation processes.
ELECTROCHIMICA ACTA
(2021)
Article
Biochemistry & Molecular Biology
Samuel Quinn, E. Stephen Davies, Nicholas Pearce, Callum Rosenberg, Constance R. R. Pfeiffer, Georgia R. F. Orton, Neil R. R. Champness
Summary: This study describes donor-acceptor dyads and triads composed of core-substituted naphthalene diimide (NDI) chromophores and either phenothiazine or phenoxazine donors. Synthesis, electrochemical, and spectroelectrochemical investigations are used to characterize the different redox states of these molecules, confirming their ability to combine electron donating and accepting moieties while retaining the individual redox properties.
Review
Chemistry, Multidisciplinary
Arijit Singha Hazari, Shubhadeep Chandra, Sanjib Kar, Biprajit Sarkar
Summary: Metal complexes of multi-porphyrins and multi-corroles have unique and interesting properties. The chemistry of metal complexes of bis-porphyrins and bis-corroles has been relatively underexplored. Despite the challenging synthesis, the exciting properties of these compounds make a strong case for further research.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Andreas C. Hans, Patrick M. Becker, Johanna Haussmann, Simon Suhr, Daniel M. Wanner, Vera Lederer, Felix Willig, Wolfgang Frey, Biprajit Sarkar, Johannes Kaestner, Rene Peters
Summary: This article discloses a catalyst type that enables highly efficient direct 1,4-additions. The catalyst is a zwitterionic entity, with acetate binding to negatively charged Cu-II and serving as a counterion for benzimidazolium. All three functionalities are involved in the catalytic activation. The productivity of maleimides increased by a factor greater than 300 compared to the literature (TONs up to 6700). High stereoselectivity and productivity were achieved for a wide range of other Michael acceptors as well. The polyfunctional catalyst, accessible in only 4 steps from N-Ph-benzimidazole with an overall yield of 96%, remained robust during catalysis, allowing for multiple reuse with nearly constant efficiency. Mechanistic studies, particularly using DFT, provided a detailed understanding of how the catalyst operates. The benzimidazolium unit stabilizes the coordinated enolate nucleophile and prevents the dissociation of acetate/acetic acid from the catalyst.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Inorganic & Nuclear
Jan Hormann, Olga Verbitsky, Xiaoyu Zhou, Beatrice Battistella, Margarete van der Meer, Biprajit Sarkar, Cunyuan Zhao, Nora Kulak
Summary: We synthesized and characterized Cu(ii) complexes CuL1-CuL6 with cyclen-based ligands. The ligands L-1-L-6 comprise different donor sets including S and O atoms. The substitution of N donor atoms with hard donor O atoms leads to efficient oxidative nucleases, but dissociation of the complex upon reduction. We are showing that the rational combination of O and S atoms next to two nitrogen donors within the macrocycle leads to the stabilization of both redox states, resulting in the highest oxidative DNA cleavage activity within this family of cyclen-based Cu(ii) complexes.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Felix Stein, Simon Suhr, Arijit Singha Hazari, Robert Walter, Maite Noessler, Biprajit Sarkar
Summary: The synthesis and characterization of cationic azide-substituted 1,2,3-triazolium salts and their reactivity towards triphenylphosphine were reported. These salts were used as building blocks to develop unsymmetrical MIC-triazene-NHC/MIC' compounds which can be converted to radicals. The investigation of these radicals using various techniques sheds new light on the stabilization ability of MICs and their pi-accepting ability.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Felix Stein, Maite Noessler, Arijit Singha Hazari, Lisa Boeser, Robert Walter, Hang Liu, Elias Klemm, Biprajit Sarkar
Summary: In recent years, terpyridines (tpy) and mesoionic carbenes (MIC) have been widely used in metal complexes. In this study, a new class of complexes was obtained by combining PFC substituted tpy and MIC ligands within the same platform, and their structural, electrochemical and UV/Vis/NIR spectroelectrochemical properties were investigated. The resulting metal complexes were found to be potent electrocatalysts for CO2 reduction, with CO exclusively formed and a faradaic efficiency of 92%. A preliminary mechanistic study, including the isolation and characterization of a key intermediate, was also reported.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Timon Kurzawa, Reinhold Zimmer, Ernst-Ulrich Wuerthwein, Hans-Ulrich Reissig
Summary: In this study, the acetic anhydride-promoted reaction of a model pyrimidine N-oxide to a 4-acetoxymethyl-substituted pyrimidine derivative was investigated. The experiments and quantum chemical calculations revealed that a (pyrimidin-4-yl)methyl radical is a key species in the rearrangement and that the reaction proceeds through radical intermediates. The calculations also showed that both concerted [3,3]-sigmatropic rearrangements and stepwise processes are energetically feasible.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Maite Noessler, Rene Jaeger, David Hunger, Marc Reimann, Tobias Bens, Nicolas I. Neuman, Arijit Singha Hazari, Martin Kaupp, Joris van Slageren, Biprajit Sarkar
Summary: Due to their ability to form stable molecular complexes, terpyridine ligands with tailor-made properties are of great interest in chemistry and material science. By synthesizing two terpyridine ligands with different fluorinated phenyl rings, we were able to prepare Co-II and Fe-II complexes and investigate their properties using various analytical techniques. Our findings revealed the structural characteristics, electrochemical behavior, and magnetic properties of these complexes, providing valuable insights into their applications and potential uses.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Simon Suhr, Nicolai Schroter, Merlin Kleoff, Nicolas Neuman, David Hunger, Robert Walter, Clemens Lucke, Felix Stein, Serhiy Demeshko, Hang Liu, Hans -Ulrich Reissig, Joris van Slageren, Biprajit Sarkar
Summary: Two homoleptic Fe(II) complexes with superbasic terpyridine derivatives as ligands were studied to investigate the relationship between spin state and electrochemical/spectroscopic behavior. Antiferromagnetic coupling between a ligand-centered radical and the high-spin metal center resulted in an anodic shift of the first reduction potential and a mixed valency species with a moderately intense intervalence-charge-transfer band. The different spin states also influenced the electrochemical reactivity, with the low-spin species acting as a precatalyst for electrocatalytic CO2 reduction and showing a Faradaic efficiency of 37% for CO formation, while the high-spin species only catalyzed proton reduction with a modest Faradaic efficiency of approximately 20%.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Tobias Bens, Jasmin A. Kubler, Robert R. M. Walter, Julia Beerhues, Oliver S. Wenger, Biprajit Sarkar
Summary: We have developed new synthetic strategies to obtain a series of Ru(II) complexes with pyridyl-mesoionic carbene ligands. By replacing bpy ligands in [Ru(bpy)3]2+ with pyridyl-MIC ligands, we were able to isolate three new complexes. We analyzed their properties using NMR spectroscopy, single-crystal X-ray diffraction analysis, cyclic voltammetry, and other techniques. These complexes showed potential applications in photocatalysis and photosensitization.
ACS ORGANIC & INORGANIC AU
(2023)
Article
Chemistry, Organic
Hans-Ulrich Reissig, Fei Yu
Summary: In this study, the nucleophilic substitution of benzylic bromides with sodium azide and copper-catalyzed cycloaddition with terminal alkynes were combined to successfully synthesize complex alkynes bearing 1,2-oxazinyl substituents. The use of tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) as a ligand for the click step was found to be highly advantageous. However, the reductive cleavage of the 1,2-oxazine rings to aminopyran moieties did not proceed cleanly with these compounds.
BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Finn Schulz, Shun Takamaru, Tobias Bens, Jun-ichi Hanna, Biprajit Sarkar, Sabine Laschat, Hiroaki Iino
Summary: This study synthesized and characterized three novel azulene-thiophene hybrid materials, and prepared uniformly flat films using the liquid crystalline phase. The thin films exhibited high mobilities in organic field effect transistors.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Julia Volk, Myron Heinz, Michael Leibold, Clemens Bruhn, Tobias Bens, Biprajit Sarkar, Max C. Holthausen, Ulrich Siemeling
Summary: Researchers have synthesized a novel cyclic compound with a 1,1'-ferrocenylene backbone, which exhibits unique structural and chemical properties. The compound's wide bond angle and redox-active backbone open up new possibilities for studying unconventional metalloradicals and oligoradicals.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Simon Suhr, Robert Walter, Julia Beerhues, Uta Albold, Biprajit Sarkar
Summary: In this contribution, we investigate Rh(iii) complexes with different substituted diamidobenzene ligands and show that the substituents on the ligands significantly affect the bonding, donor, electrochemical and spectroscopic properties of the Rh complexes. We also present design strategies for the isolation of mononuclear Rh(ii) metallates with high redox potentials and discover the reactivity of the metal complexes with small molecules.
Article
Chemistry, Inorganic & Nuclear
Maite Noessler, David Hunger, Nicolas Neuman, Marc Reimann, Felix Reichert, Mario Winkler, Johannes Klein, Tobias Bens, Lisa Suntrup, Serhiy Demeshko, Jessica Stubbe, Martin Kaupp, Joris van Slageren, Biprajit Sarkar
Summary: Controlling the spin state of metal complexes is crucial for manipulating their physical and chemical properties. Currently, this control is challenging due to the difficulties in precisely controlling the properties of the secondary coordination sphere. This study demonstrates that non-covalent interactions in the secondary coordination sphere can enable spin state control in metal complexes. By using fluorinated triazole ligands, mononuclear Co-II and Fe-II complexes with specific fluorinated benzyl substituents were synthesized and characterized. The spin state of the metal center was found to be influenced by the substituents and geometric structure, as revealed by magnetometry and spectroscopy. Quantum-chemical calculations provided insight into the role of fluorine-specific interactions. Notably, this work highlights the ability of the same fluorinated tripodal ligands to induce spin crossover behavior in both Fe-II and Co-II complexes.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Multidisciplinary
Ramananda Maity, Biprajit Sarkar
Summary: This paper provides an overview of recent developments in the field of 1,2,3-triazolylidene-type Mesoionic carbenes (MICs). These compounds are popular due to their modular synthesis and strong donor properties, and have found applications with both transition metals and main group elements. The paper discusses various aspects of MIC-containing compounds, including their synthesis, spectroscopic properties, and potential applications in catalysis and small-molecule activation.
