90 results on '"Spectroscopy and Catalysis"'
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2. Conductive Polyisocyanide Hydrogels Inhibit Fibrosis and Promote Myogenesis.
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Kumari, J., Paul, O., Verdellen, L., Berking, B.B., Chen, W., Gerrits, L., Postma, Jelle, Wagener, F.A.D.T.G., Kouwer, P.H.J., Kumari, J., Paul, O., Verdellen, L., Berking, B.B., Chen, W., Gerrits, L., Postma, Jelle, Wagener, F.A.D.T.G., and Kouwer, P.H.J.
- Abstract
Contains fulltext : 306408.pdf (Publisher’s version ) (Open Access), Reliable in vitro models closely resembling native tissue are urgently needed for disease modeling and drug screening applications. Recently, conductive biomaterials have received increasing attention in the development of in vitro models as they permit exogenous electrical signals to guide cells toward a desired cellular response. Interestingly, they have demonstrated that they promote cellular proliferation and adhesion even without external electrical stimulation. This paper describes the development of a conductive, fully synthetic hydrogel based on hybrids of the peptide-modified polyisocyanide (PIC-RGD) and the relatively conductive poly(aniline-co-N-(4-sulfophenyl)aniline) (PASA) and its suitability as the in vitro matrix. We demonstrate that incorporating PASA enhances the PIC-RGD hydrogel's electroactive nature without significantly altering the fibrous architecture and nonlinear mechanics of the PIC-RGD network. The biocompatibility of our model was assessed through phenotyping cultured human foreskin fibroblasts (HFF) and murine C2C12 myoblasts. Immunofluorescence analysis revealed that PIC-PASA hydrogels inhibit the fibrotic behavior of HFFs while promoting myogenesis in C2C12 cells without electrical stimulation. The composite PIC-PASA hydrogel can actively change the cell fate of different cell types, providing an attractive tool to improve skin and muscle repair.
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- 2024
3. Supramolecular Materials from Porphyrins and Phthalocyanines
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Nolte, R.J.M., Elemans, J.A.A.W., and Azzaroni, O.
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Spectroscopy and Catalysis ,Physical Organic Chemistry - Abstract
Item does not contain fulltext
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- 2023
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4. A Search for Pulsars around Sgr A* in the First Event Horizon Telescope Data Set
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Torne, P., Liu, K., Eatough, R.P., Brinkerink, C.D., Bronzwaer, T.J.W., Davelaar, J., Falcke, H., Fraga-Encinas, R., Issaoun, S., Jiménez-Rosales, A., La Bella, N., Moscibrodzka, M.A., Müller, C., Musoke, G.R., Olivares, H., Roelofs, F.J., Tilanus, R.P.J., Rossum, D.R. van, Vos, J., Wondrak, M.F., Yfantis, A.I., Young, A., Zhang, S., Zhao, G. -Y., Zhao, S.-S., Torne, P., Liu, K., Eatough, R.P., Brinkerink, C.D., Bronzwaer, T.J.W., Davelaar, J., Falcke, H., Fraga-Encinas, R., Issaoun, S., Jiménez-Rosales, A., La Bella, N., Moscibrodzka, M.A., Müller, C., Musoke, G.R., Olivares, H., Roelofs, F.J., Tilanus, R.P.J., Rossum, D.R. van, Vos, J., Wondrak, M.F., Yfantis, A.I., Young, A., Zhang, S., Zhao, G. -Y., and Zhao, S.-S.
- Abstract
Contains fulltext : 299453.pdf (Publisher’s version ) (Open Access)
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- 2023
5. Kinetic enantio-recognition of chiral viologen guests by planar-chiral porphyrin cages
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Gilissen, Pieter J., Duez, Q.C.N., Tripodi, G.L., Dekker, Magda M.J., Ouyang, Jiangkun, Dhbaibi, Kais, Roithova, Jana, Elemans, Johannes A.A.W., Nolte, R.J.M., Gilissen, Pieter J., Duez, Q.C.N., Tripodi, G.L., Dekker, Magda M.J., Ouyang, Jiangkun, Dhbaibi, Kais, Roithova, Jana, Elemans, Johannes A.A.W., and Nolte, R.J.M.
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Contains fulltext : 298932.pdf (Publisher’s version ) (Open Access)
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- 2023
6. Aliphatic and Aromatic C–H Bond Oxidation by High-Valent Manganese(IV)-Hydroxo Species
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Yujeong Lee, Guilherme L. Tripodi, Donghyun Jeong, Sunggi Lee, Jana Roithova, and Jaeheung Cho
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Anthracenes ,Manganese ,Kinetics ,Colloid and Surface Chemistry ,Spectroscopy and Catalysis ,General Chemistry ,Oxidation-Reduction ,Biochemistry ,Catalysis ,Hydrogen - Abstract
The strong C-H bond activation of hydrocarbons is a difficult reaction in environmental and biological chemistry. Herein, a high-valent manganese(IV)-hydroxo complex, [Mn
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- 2022
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7. Octahedral Iron‐Acyl‐Nitrenoid Intermediates in Sulphur −Nitrogen Coupling and Hydrogen Atom Transfer Reactions
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Mònica Rodríguez, Aleksandr Y. Pereverzev, and Jana Roithová
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Inorganic Chemistry ,Organic Chemistry ,Spectroscopy and Catalysis ,Physical and Theoretical Chemistry ,Catalysis - Abstract
Contains fulltext : 293925.pdf (Publisher’s version ) (Open Access) 05 juni 2023
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- 2023
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8. Bis(3-methyl-1-propyl-1,3-dihydro-1H-imidazol-2-ylidene)silver(I) chlorido(5,10,15,20-tetraphenylporphinato)cadmate(II)
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J. P. J. Bruekers, J. A. A. W. Elemans, R. J. M. Nolte, and P. Tinnemans
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Spectroscopy and Catalysis ,Solid State Chemistry ,Physical Organic Chemistry - Abstract
The structure of the title salt, [Ag(C7H12N2)2][CdCl(C44H28N4)], at 150 K has triclinic symmetry. One of the phenyl rings bonded to the porphyrin molecule and the propyl groups of both ylidene molecules coordinating to silver are disordered over two positions.
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- 2022
9. Sulfonyl Nitrene and Amidyl Radical: Structure and Reactivity
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Jan Zelenka, Aleksandr Pereverzev, Ullrich Jahn, and Jana Roithová
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Electron Transport ,Azides ,Organic Chemistry ,Spectroscopy and Catalysis ,Imines ,General Chemistry ,Protons ,Catalysis ,Hydrogen - Abstract
Photocatalytic generation of nitrenes and radicals can be used to tune or even control their reactivity. Photocatalytic activation of sulfonyl azides leads to the elimination of N
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- 2022
10. Can Copper(I) and Silver(I) be Hydrogen Bond Acceptors?
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Erik Andris, Michal Straka, Jan Vrána, Aleš Růžička, Jana Roithová, and Lubomír Rulíšek
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Organic Chemistry ,Spectroscopy and Catalysis ,General Chemistry ,Catalysis - Abstract
Contains fulltext : 292790.pdf (Publisher’s version ) (Open Access)
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- 2023
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11. Mechanistic studies of the palladium-catalyzed S,O-ligand promoted C-H olefination of aromatic compounds
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Kananat Naksomboon, Enrique Gómez-Bengoa, Jaya Mehara, Jana Roithová, Edwin Otten, M. Ángeles Fernández-Ibáñez, and Molecular Energy Materials
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Spectroscopy and Catalysis ,General Chemistry - Abstract
Pd-catalyzed C–H functionalization reactions of non-directed substrates have recently emerged as an attractive alternative to the use of directing groups. Key to the success of these transformations has been the discovery of new ligands capable of increasing both the reactivity of the inert C–H bond and the selectivity of the process. Among them, a new type of S,O-ligand has been shown to be highly efficient in promoting a variety of Pd-catalyzed C–H olefination reactions of non-directed arenes. Despite the success of this type of S,O-ligand, its role in the C–H functionalization processes is unknown. Herein, we describe a detailed mechanistic study focused on elucidating the role of the S,O- ligand in the Pd-catalyzed C–H olefination of non-directed arenes. For this purpose, several mechanistic tools, including isolation and characterization of reactive intermediates, NMR and kinetic studies, isotope effects and DFT calculations have been employed. The data from these experiments suggest that the C–H activation is the rate-determining step in both cases with and without the S,O-ligand. Furthermore, the results indicate that the S,O-ligand triggers the formation of more reactive Pd cationic species, which explains the observed acceleration of the reaction. Together, these studies shed light on the role of the S,O-ligand in promoting Pd-catalyzed C–H functionalization reactions We acknowledge nancial support from NWO through a VIDI grant (723.013.006) and from MCIN-PID2019-110008GB-I00. E. G.-B. thanks SGIker (UPV/EHU) for providing human and computational resources.
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- 2023
12. Hydrogen Bonding Effect on the Oxygen Binding and Activation in Cobalt(III)-Peroxo Complexes
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Rob Bakker, Abhinav Bairagi, Mònica Rodríguez, Guilherme L. Tripodi, Aleksandr Y. Pereverzev, and Jana Roithová
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Inorganic Chemistry ,Spectroscopy and Catalysis ,Physical and Theoretical Chemistry - Abstract
Contains fulltext : 290658.pdf (Publisher’s version ) (Open Access)
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- 2023
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13. Enantiodivergent Sulfoxidation Catalyzed by a Photoswitchable Iron Salen Phosphate Complex
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Pieter J. Gilissen, Xiaofei Chen, Joep De Graaf, Paul Tinnemans, Ben L. Feringa, Johannes A. A. W. Elemans, Roeland J. M. Nolte, Stratingh Institute of Chemistry, and Synthetic Organic Chemistry
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Hammett plot ,Organic Chemistry ,Spectroscopy and Catalysis ,asymmetric catalysis ,photoresponsive ,Solid State Chemistry ,General Chemistry ,Physical Organic Chemistry ,Catalysis ,sulfoxidation ,supramolecular chemistry - Abstract
Here we describe a photoswitchable iron(III) salen phosphate catalyst, which is able to catalyze the enantiodivergent oxidation of prochiral aryl alkyl sulfides to chiral aryl alkyl sulfoxides. The stable (S)-axial isomer of the catalyst produced enantioenriched sulfoxides with the (R)-configuration in up to 75 % e.e., whereas the photoisomerized metastable (R)-axial isomer of the catalyst favored the formation of (S)-sulfoxides in up to 43 % e.e. The maximum Δe.e. value obtained in the enantiodivergent sulfoxidation was 118 %, which is identical to the maximum Δe.e. value that was measured in the enantiodivergent epoxidation of alkenes by a related recently described Mn1 catalyst. This iron-based catalyst broadens the scope of photoswitchable enantiodivergent catalysts and may be used in the future to develop a photoswitchable catalytic system that can write digital information on a polymer chain in the form chiral sulfoxide functions.
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- 2023
14. Copper(II)-TEMPO Interaction
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Jaya Mehara and Jana Roithová
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Spectroscopy and Catalysis ,General Chemistry - Abstract
Contains fulltext : 292792.pdf (Publisher’s version ) (Open Access) 01 mei 2023
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- 2023
15. Spectroscopic Evidence for a Cobalt-Bound Peroxyhemiacetal Intermediate
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Yeongjin Son, Aleksandr Pereverzev, Jaeheung Cho, Guilherme L. Tripodi, Kyungmin Kim, Seonghan Kim, and Jana Roithová
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chemistry.chemical_classification ,Letter ,Direct evidence ,aldehyde deformylation ,chemistry.chemical_element ,Aldehyde ,Medicinal chemistry ,Adduct ,bioinorganic chemistry ,Metal ,Isotopic labeling ,Chemistry ,chemistry ,Nucleophile ,peroxyhemiacetal species ,dichotomic reactivity ,visual_art ,visual_art.visual_art_medium ,Spectroscopy and Catalysis ,Reactivity (chemistry) ,Cobalt ,QD1-999 ,cobalt-dioxygen adduct - Abstract
Aldehyde deformylation reactions by metal dioxygen adducts have been proposed to involve peroxyhemiacetal species as key intermediates. However, direct evidence of such intermediates has not been obtained to date. We report the spectroscopic characterization of a mononuclear cobalt(III)-peroxyhemiacetal complex, [Co(Me3-TPADP)(O2CH(O)CH(CH3)C6H5)]+ (2), in the reaction of a cobalt(III)-peroxo complex (1) with 2-phenylpropionaldehyde (2-PPA). The formation of 2 is also investigated by isotope labeling experiments and kinetic studies. The conclusion that the peroxyhemiacetalcobalt(III) intermediate is responsible for the aldehyde deformylation is supported by the product analyses. Furthermore, isotopic labeling suggests that the reactivity of the cobalt(III)-peroxo complex depends on the second reactant. The aldehyde inserts between the oxygen atoms of 1, whereas the reaction with acyl chlorides proceeds by a nucleophilic attack. The observation of the peroxyhemiacetal intermediate provides significant insight into the initial step of aldehyde deformylation by metalloenzymes.
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- 2021
16. Computing Arithmetic Functions Using Immobilised Enzymatic Reaction Networks
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Nikita M. Ivanov, Mathieu G. Baltussen, Cristina Lía Fernández Regueiro, Max T. G. M. Derks, and Wilhelm T. S. Huck
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Spectroscopy and Catalysis ,General Chemistry ,General Medicine ,Catalysis ,Physical Organic Chemistry - Abstract
Living systems use enzymatic reaction networks to process biochemical information and make decisions in response to external or internal stimuli. Here, we present a modular and reusable platform for molecular information processing using enzymes immobilised in hydrogel beads and compartmentalised in a continuous stirred tank reactor. We demonstrate how this setup allows us to perform simple arithmetic operations, such as addition, subtraction and multiplication, using various concentrations of substrates or inhibitors as inputs and the production of a fluorescent molecule as the readout.
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- 2022
17. Host‐guest tuning of the CO 2 reduction activity of an iron porphyrin cage
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Adarsh Koovakattil Surendran, Guilherme L. Tripodi, Eva Pluhařová, Aleksandr Y. Pereverzev, Jeroen P. J. Bruekers, Johannes A. A. W. Elemans, Evert Jan Meijer, and Jana Roithová
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Cultural Studies ,Linguistics and Language ,History ,Anthropology ,Spectroscopy and Catalysis ,Physical Organic Chemistry ,Language and Linguistics - Abstract
Contains fulltext : 287543.pdf (Publisher’s version ) (Open Access) 28 november 2022
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- 2022
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18. Tracking Reaction Pathways by a Modular Flow Reactor Coupled to Electrospray Ionization Mass Spectrometry
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Max T. G. M. Derks, Jana Roithová, Floris P. J. T. Rutjes, and Guilherme L. Tripodi
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Reaction mechanism ,Chromatography ,business.industry ,Chemistry ,010405 organic chemistry ,Electrospray ionization ,Synthetic Organic Chemistry ,Flow chemistry ,General Medicine ,Modular design ,Tracking (particle physics) ,Mass spectrometry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Flow (mathematics) ,Spectroscopy and Catalysis ,business - Abstract
Contains fulltext : 245382.pdf (Publisher’s version ) (Open Access)
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- 2021
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19. Synthetic fibrous hydrogels as a platform to decipher cell-matrix mechanical interactions
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Hongbo Yuan, Kaizheng Liu, Mar Cóndor, Jorge Barrasa-Fano, Boris Louis, Johannes Vandaele, Paula de Almeida, Quinten Coucke, Wen Chen, Egbert Oosterwijk, Chengfen Xing, Hans Van Oosterwyck, Paul H. J. Kouwer, and Susana Rocha
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Multidisciplinary ,Systems Chemistry ,Molecular Materials ,Urological cancers Radboud Institute for Molecular Life Sciences [Radboudumc 15] ,Spectroscopy and Catalysis ,cellular traction forces ,Hydrogels ,Cell Communication ,mechanobiology ,cell–matrix interactions ,nonlinear mechanics ,biomaterials ,Extracellular Matrix - Abstract
Cells continuously sense external forces from their microenvironment, the extracellular matrix (ECM). In turn, they generate contractile forces, which stiffen and remodel this matrix. Although this bidirectional mechanical exchange is crucial for many cell functions, it remains poorly understood. Key challenges are that the majority of available matrices for such studies, either natural or synthetic, are difficult to control or lack biological relevance. Here, we use a synthetic, yet highly biomimetic hydrogel based on polyisocyanide (PIC) polymers to investigate the effects of the fibrous architecture and the nonlinear mechanics on cell-matrix interactions. Live-cell rheology was combined with advanced microscopy-based approaches to understand the mechanisms behind cell-induced matrix stiffening and plastic remodeling. We demonstrate how cell-mediated fiber remodeling and the propagation of fiber displacements are modulated by adjusting the biological and mechanical properties of this material. Moreover, we validate the biological relevance of our results by demonstrating that cellular tractions in PIC gels develop analogously to those in the natural ECM. This study highlights the potential of PIC gels to disentangle complex bidirectional cell-matrix interactions and to improve the design of materials for mechanobiology studies. ispartof: Proc Natl Acad Sci U S A vol:120 issue:15 pages:e2216934120- ispartof: location:United States status: published
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- 2022
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20. Do Sulfonamides Interact with Aromatic Rings?
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Roel Hammink, Jasmin Mecinović, Jie Jian, Christine J. McKenzie, F. Matthias Bickelhaupt, Jordi Poater, Chemistry and Pharmaceutical Sciences, AIMMS, and Theoretical Chemistry
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Models, Molecular ,Stereochemistry ,Drug design ,Synthetic Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,noncovalent interactions ,Molecular recognition ,polar–pi interactions ,sulfonamides ,Spectroscopy and Catalysis ,Non-covalent interactions ,Moiety ,Theoretical Chemistry ,chemistry.chemical_classification ,Sulfonamides ,010405 organic chemistry ,Hydrogen bond ,aromatic compounds ,Organic Chemistry ,Proteins ,Aromaticity ,Hydrogen Bonding ,General Chemistry ,0104 chemical sciences ,Sulfonamide ,chemistry ,Proton affinity ,molecular recognition ,Protons - Abstract
Aromatic rings form energetically favorable interactions with many polar groups in chemical and biological systems. Recent molecular studies have shown that sulfonamides can chelate metal ions and form hydrogen bonds, however, it is presently not established whether the polar sulfonamide functionality also interacts with aromatic rings. Here, synthetic, spectroscopic, structural, and quantum chemical analyses on 2,6-diarylbenzenesulfonamides are reported, in which two flanking aromatic rings are positioned close to the central sulfonamide moiety. Fine-tuning the aromatic character by substituents on the flanking rings leads to linear trends in acidity and proton affinity of sulfonamides. This physical-organic chemistry study demonstrates that aromatic rings have a capacity to stabilize sulfonamides via through-space NH–π interactions. These results have implications in rational drug design targeting electron-rich aromatic rings in proteins.
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- 2021
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21. Enantioselective synthesis of chiral porphyrin macrocyclic hosts and kinetic enantiorecognition of viologen guests
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Annemiek D. Slootbeek, Johannes A. A. W. Elemans, Jiang-Kun Ou-Yang, Nicolas Vanthuyne, Pieter J. Gilissen, Rob Bakker, Roeland J. M. Nolte, Institute for Molecules and Materials [Nijmegen], Radboud university [Nijmegen], Institut des Sciences Moléculaires de Marseille (ISM2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Radboud University [Nijmegen]
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Stereochemistry ,High Energy Physics::Lattice ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Spectroscopy and Catalysis ,medicine ,[CHIM]Chemical Sciences ,Computer Science::Operating Systems ,010405 organic chemistry ,Chemistry ,High Energy Physics::Phenomenology ,Enantioselective synthesis ,Viologen ,General Chemistry ,Porphyrin ,3. Good health ,0104 chemical sciences ,Stereoselectivity ,Threading (protein sequence) ,Enantiomer ,Selectivity ,Physical Organic Chemistry ,Macromolecule ,medicine.drug - Abstract
The construction of macromolecular hosts that are able to thread chiral guests in a stereoselective fashion is a big challenge. We herein describe the asymmetric synthesis of two enantiomeric C2-symmetric porphyrin macrocyclic hosts that thread and bind different viologen guests. Time-resolved fluorescence studies show that these hosts display a factor 3 kinetic preference (ΔΔG‡on = 3 kJ mol−1) for threading onto the different enantiomers of a viologen guest appended with bulky chiral 1-phenylethoxy termini. A smaller kinetic selectivity (ΔΔG‡on = 1 kJ mol−1) is observed for viologens equipped with small chiral sec-butoxy termini. Kinetic selectivity is absent when the C2-symmetric hosts are threaded onto chiral viologens appended with chiral tails in which the chiral moieties are located in the centers of the chains, rather than at the chain termini. The reason is that the termini of the latter guests, which engage in the initial stages of the threading process (entron effect), cannot discriminate because they are achiral, in contrast to the chiral termini of the former guests. Finally, our experiments show that the threading and de-threading rates are balanced in such a way that the observed binding constants are highly similar for all the investigated host–guest complexes, i.e. there is no thermodynamic selectivity., Chiral guests display kinetic stereoselective threading through chiral porphyrin cages if their chirality is located at the chain ends and not in the centers, supporting the previously reported entron effect of threading.
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- 2021
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22. 1,1'-Methylenebis(4-tert-butylpyridinium) dichloride hemihydrate
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Johannes A. A. W. Elemans, Roeland J. M. Nolte, Jeroen P. J. Bruekers, and Paul Tinnemans
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Tert butyl ,chemistry.chemical_classification ,crystal structure ,cl...π contacts ,Crystallography ,Hemihydrate ,Salt (chemistry) ,Crystal structure ,Solid State Chemistry ,Rotation ,o—h...cl hydrogen bonds ,chemistry.chemical_compound ,chemistry ,QD901-999 ,Spectroscopy and Catalysis ,Pyridinium ,Symmetry (geometry) ,Physical Organic Chemistry ,Monoclinic crystal system - Abstract
The structure of the title hydrated salt, C19H28N2 2+·2Cl−·0.5H2O, at 150 K has monoclinic (C2/c) symmetry. The water molecule is located on a twofold rotation axis.
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- 2021
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23. Fibrous Hydrogels under Multi-Axial Deformation: Persistence Length as the Main Determinant of Compression Softening
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Paul H. J. Kouwer, Paul A. Janmey, and Paula de Almeida
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Persistence length ,Materials science ,Systems Chemistry ,02 engineering and technology ,Deformation (meteorology) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Compression (physics) ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Self-healing hydrogels ,Spectroscopy and Catalysis ,Electrochemistry ,Multi axial ,Composite material ,0210 nano-technology ,Softening - Abstract
Contains fulltext : 235937.pdf (Publisher’s version ) (Open Access) 24 maart 2021
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- 2021
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24. Mechanistic Study of Pd/NHC‐Catalyzed Sonogashira Reaction: Discovery of NHC‐Ethynyl Coupling Process
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Dmitry B. Eremin, Alexander Yu. Kostyukovich, Jana Roithová, Valentine P. Ananikov, Mariarosa Anania, Ekaterina A. Denisova, Daniil A. Boiko, Jos Oomens, Julia V. Burykina, Giel Berden, and Jonathan Martens
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FELIX Molecular Structure and Dynamics ,chemistry.chemical_classification ,Collision-induced dissociation ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Sonogashira coupling ,Alkyne ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Bond-dissociation energy ,Catalysis ,Dissociation (chemistry) ,0104 chemical sciences ,Molecular dynamics ,Computational chemistry ,Spectroscopy and Catalysis ,Infrared multiphoton dissociation - Abstract
The product of a revealed transformation-NHC-ethynyl coupling-was observed as a catalyst transformation pathway in the Sonogashira cross-coupling, catalyzed by Pd/NHC complexes. The 2-ethynylated azolium salt was isolated in individual form and fully characterized, including X-ray analysis. A number of possible intermediates of this transformation with common formulae (NHC)n Pd(C2 Ph) (n=1,2) were observed and subjected to collision-induced dissociation (CID) and infrared multiphoton dissociation (IRMPD) experiments to elucidate their structure. Measured bond dissociation energies (BDEs) and IRMPD spectra were in an excellent agreement with quantum calculations for coupling product π-complexes with Pd0 . Molecular dynamics simulations confirmed the observed multiple CID fragmentation pathways. An unconventional methodology to study catalyst evolution suggests the reported transformation to be considered in the development of new catalytic systems for alkyne functionalization reactions.
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- 2020
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25. Gel Casting as an Approach for Tissue Engineering of Multilayered Tubular Structures
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Debby Gawlitta, Laetitia M.O. de Kort, Jos Malda, Franziska S. Zügel, Pedro F. Costa, Rana Ramadan, Petra de Graaf, Barbara J. Klotz, Melissa J.J. van Velthoven, Miguel Castilho, Orthopaedic Biomechanics, EAISI Health, and ICMS Affiliated
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Materials science ,Cell Survival ,0206 medical engineering ,Green Fluorescent Proteins ,Myocytes, Smooth Muscle ,Biomedical Engineering ,Medicine (miscellaneous) ,Neovascularization, Physiologic ,Bioengineering ,macromolecular substances ,02 engineering and technology ,urologic and male genital diseases ,SDG 3 – Goede gezondheid en welzijn ,03 medical and health sciences ,Tissue engineering ,vascularization ,SDG 3 - Good Health and Well-being ,Human Umbilical Vein Endothelial Cells ,Spectroscopy and Catalysis ,Humans ,urology ,hydrogels ,030304 developmental biology ,0303 health sciences ,Tissue Engineering ,urogenital system ,Molecular Materials ,020601 biomedical engineering ,female genital diseases and pregnancy complications ,Coculture Techniques ,Male urethra ,Luminescent Proteins ,nervous system ,Self-healing hydrogels ,Gel casting ,Pericytes ,Gels ,Biomedical engineering - Abstract
Several urological structures, such as the male urethra, have a tubular organization consisting of different layers. However, in severe urethral disease, urologists are limited to replacing solely the epithelial layer. In case of severe hypospadias and urethral stricture disease, the underlying supporting structure (the corpus spongiosum) is either absent or fibrotic, causing suboptimal vascularization and therefore increasing the risk of graft failure. Recapitulating the multilayered architecture of the urethra, including supporting structure with tissue engineering, might minimize urethral graft failure. However, current tissue engineering applications for complex multilayered tubular constructs are limited. We describe a gel casting method to tissue engineer multilayered tubular constructs based on fiber-reinforced cell-laden hydrogels. For this, a multichambered polydimethylsiloxane mold was casted with fiber-reinforced hydrogels containing smooth muscle cells (SMCs) and a coculture of endothelial cells and pericytes. The cell-loaded hydrogels were rolled, with the fiber mesh as guidance, into a tubular construct. In the lumen, urothelial cells were seeded and survived for 2 weeks. In the tubular construct, the cells showed good viability and functionality: endothelial cells formed capillary-like structures supported by pericytes and SMCs expressed elastin. With a graft produced by this technique, supported with subepithelial vascularization, urethral reconstructive surgery can be improved. This approach toward tissue engineering of multilayered tubular structures can also be applied to other multilayered tubular structures found in the human body. Impact Statement Recapitulating the multilayered architecture of tubular structures found in the human body might minimize graft failure. Current tissue engineering applications for complex multilayered tubular constructs are limited. Here we describe a gel casting approach based on fiber-reinforced cell-laden hydrogels. A multichambered polydimethylsiloxane mold was casted with cell-loaded, fiber-reinforced hydrogels, with the fiber mesh as guidance, into a tubular construct. A graft produced by this technique can improve reconstructive surgery by providing subepithelial vascularization and thereby can reduce graft failure.
- Published
- 2020
26. Biofabrication of a Functional Tubular Construct from Tissue Spheroids Using Magnetoacoustic Levitational Directed Assembly
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Vladislav A. Parfenov, P. A. Karalkin, Elena A. Bulanova, Vladimir Mironov, Elizaveta V. Koudan, Oleg A. Sapozhnikov, E. A. Annenkova, Peter C. M. Christianen, Elizaveta K. Nezhurina, Peter M. van der Kraan, Alisa A. Krokhmal, Vladimir Kasyanov, A. A. Gryadunova, Yusef D. Khesuani, Egbert Oosterwijk, Hans Engelkamp, Stanislav V. Petrov, S.J.C. Granneman, Henk M. van Beuningen, F. D. A. S. Pereira, Sergey A. Tsysar, and Kaizheng Liu
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Materials science ,Human bladder ,Biomedical Engineering ,Pharmaceutical Science ,Biocompatible Materials ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biomaterial scaffold ,Biomaterials ,All institutes and research themes of the Radboud University Medical Center ,Tissue engineering ,Smooth muscle ,Soft Condensed Matter and Nanomaterials ,Spheroids, Cellular ,Urological cancers Radboud Institute for Molecular Life Sciences [Radboudumc 15] ,Spectroscopy and Catalysis ,Humans ,Volume concentration ,Acoustic field ,Tissue Engineering ,Tissue Scaffolds ,Molecular Materials ,Spheroid ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Magnetic Fields ,0210 nano-technology ,Inflammatory diseases Radboud Institute for Molecular Life Sciences [Radboudumc 5] ,Biofabrication ,Biomedical engineering ,Biotechnology - Abstract
In traditional tissue engineering, synthetic or natural scaffolds are usually used as removable temporal support, which involves some biotechnology limitations. The concept of "scaffield" approach utilizing the physical fields instead of biomaterial scaffold has been proposed recently. In particular, a combination of intense magnetic and acoustic fields can enable rapid levitational bioassembly of complex-shaped 3D tissue constructs from tissue spheroids at low concentration of paramagnetic agent (gadolinium salt) in the medium. In the current study, the tissue spheroids from human bladder smooth muscle cells (myospheres) are used as building blocks for assembling the tubular 3D constructs. Levitational assembly is accomplished at low concentrations of gadolinium salts in the high magnetic field at 9.5 T. The biofabricated smooth muscle constructs demonstrate contraction after the addition of vasoconstrictive agent endothelin-1. Thus, hybrid magnetoacoustic levitational bioassembly is considered as a new technology platform in the emerging field of formative biofabrication. This novel technology of scaffold-free, nozzle-free, and label-free bioassembly opens a unique opportunity for rapid biofabrication of 3D tissue and organ constructs with complex geometry.
- Published
- 2020
27. Mechanistic Investigation of Photochemical Reactions by Mass Spectrometry
- Author
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Jan Zelenka and Jana Roithová
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chemistry.chemical_classification ,Spectrometry, Mass, Electrospray Ionization ,Photoisomerization ,010405 organic chemistry ,Biomolecule ,Electrospray ionization ,Organic Chemistry ,Reaction intermediate ,Photochemical Processes ,010402 general chemistry ,Mass spectrometry ,Photochemistry ,01 natural sciences ,Biochemistry ,Mass spectrometric ,0104 chemical sciences ,Characterization (materials science) ,chemistry ,Spectroscopy and Catalysis ,Molecular Medicine ,Peptides ,Spectroscopy ,Molecular Biology - Abstract
This Minireview highlights the application of electrospray ionization mass spectrometry (ESI-MS) to investigating photochemical reactions. We show possible approaches to on-line ESI-MS monitoring of photocatalytic reactions and give examples of the characterization of short-lived photochemical intermediates by ion spectroscopy. The minireview also exemplifies in-depth mass spectrometric studies of photoisomerization reactions and photofragmentation reactions. Apart from mechanistic studies, the coupling of photochemistry and mass spectrometry is a powerful approach to studying structure and properties of biomolecules. We show several examples focused on investigation of intrinsic properties of model biomolecules.
- Published
- 2020
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28. Mechanistic Studies on the Epoxidation of Alkenes by Macrocyclic Manganese Porphyrin Catalysts
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Xiaofei Chen, Quentin Duez, Guilherme L. Tripodi, Pieter J. Gilissen, Dimitrios Piperoudis, Paul Tinnemans, Johannes A. A. W. Elemans, Jana Roithová, and Roeland J. M. Nolte
- Subjects
Organic Chemistry ,Spectroscopy and Catalysis ,Solid State Chemistry ,Physical and Theoretical Chemistry ,Physical Organic Chemistry - Abstract
Macrocyclic metal porphyrin complexes can act as shape-selective catalysts mimicking the action of enzymes. To achieve enzyme-like reactivity, a mechanistic understanding of the reaction at the molecular level is needed. We report a mechanistic study of alkene epoxidation by the oxidant iodosylbenzene, mediated by an achiral and a chiral manganese(V)oxo porphyrin cage complex. Both complexes convert a great variety of alkenes into epoxides in yields varying between 20-88 %. We monitored the process of the formation of the manganese(V)oxo complexes by oxygen transfer from iodosylbenzene to manganese(III) complexes and their reactivity by ion mobility mass spectrometry. The results show that in the case of the achiral cage complex the initial iodosylbenzene adduct is formed on the inside of the cage and in the case of the chiral one on the outside of the cage. Its decomposition leads to a manganese complex with the oxo ligand on either the inside or outside of the cage. These experimental results are confirmed by DFT calculations. The oxo ligand on the outside of the cage reacts faster with a substrate molecule than the oxo ligand on the inside. The results indicate how the catalytic activity of the macrocyclic porphyrin complex can be tuned and explain why the chiral porphyrin complex does not catalyze the enantioselective epoxidation of alkenes.
- Published
- 2022
29. Supramolecular Catalysis by Metallohosts Based on Glycoluril
- Author
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Bruekers, J.P.J., Elemans, J.A.A.W., Nolte, R.J.M., Leeuwen, P.W.N.M. van, and Leeuwen, P.W.N.M. van
- Subjects
Spectroscopy and Catalysis ,Physical Organic Chemistry - Abstract
Item does not contain fulltext
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- 2022
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30. Enantiodivergent epoxidation of alkenes with a photoswitchable phosphate manganese-salen complex
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Xiaofei Chen, Pieter J. Gilissen, Paul Tinnemans, Nicolas Vanthuyne, Floris P. J. T. Rutjes, Ben L. Feringa, Johannes A. A. W. Elemans, Roeland J. M. Nolte, and Synthetic Organic Chemistry
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Spectroscopy and Catalysis ,Solid State Chemistry ,Synthetic Organic Chemistry ,Physical Organic Chemistry - Abstract
The development of enantiodivergent catalysts capable of preparing both enantiomeric products from one substrate in a controlled fashion is challenging. Introducing a switching function into the catalyst can address this challenge, allowing the chiral reaction environment to reversibly change during catalysis. Here we report a photoswitchable phosphate ligand, derived from 2,2'-biphenol, which axially coordinates as the counter ion to an achiral manganese(III) salen catalyst, providing the latter with the ability to switch stereoselectivity in the epoxidation of alkenes. The enantiomers of the chiral ligand exist as a pair of pseudo-enantiomers, which can be interconverted by irradiation with light of different wavelengths. The opposite axial chirality of these pseudo-enantiomers is efficiently transferred to the manganese(III) salen catalyst. With this switchable supramolecular catalyst, the enantioselectivity of the epoxidation of a variety of alkenes can be controlled, resulting in opposite enantiomeric excesses of the epoxide products. This transfer of chirality from a photoswitchable anionic ligand to a metal complex broadens the scope of supramolecular catalysts.
- Published
- 2022
31. Paramagnetic relaxation enhancement NMR as a tool to probe guest binding and exchange in metallohosts
- Author
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Anne Swartjes, Paul B. White, Jeroen P. J. Bruekers, Johannes A. A. W. Elemans, and Roeland J. M. Nolte
- Subjects
Multidisciplinary ,Spectroscopy and Catalysis ,General Physics and Astronomy ,General Chemistry ,Synthetic Organic Chemistry ,General Biochemistry, Genetics and Molecular Biology ,Physical Organic Chemistry - Abstract
Paramagnetic metallohost systems can bind guest molecules and find application as biomimetic catalysts. Due to the presence of the paramagnetic metal center, rigorous characterization of these systems by NMR spectroscopy can be very difficult. We report here that metallohost-guest systems can be studied by using the paramagnetic relaxation enhancement (PRE) effect. Manganese(III) porphyrin cage compounds are shown through their PRE to thread and bind viologen guests, including a polymeric one. The binding constants and dethreading activation parameters are lower than those of the metal-free porphyrin cage compounds, which is proposed to be a result of charge repulsion of the trivalent metal center and dicationic viologen guest. The threading rate of the manganese(III) porphyrin cage onto the polymer is more than 10 times faster than that of the non-metallated one, which is ascribed to initial binding of the cage to the polymer chain prior to threading, and to an entron effect.
- Published
- 2022
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32. Binding Interactions in Copper, Silver and Gold pi-Complexes
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Jaya Mehara, Brandon T. Watson, Anurag Noonikara‐Poyil, Adway O. Zacharias, Jana Roithová, and H. V. Rasika Dias
- Subjects
Silver ,Organic Chemistry ,Spectroscopy and Catalysis ,Gold ,General Chemistry ,Crystallography, X-Ray ,Ligands ,Copper ,Catalysis - Abstract
The copper(I), silver(I), and gold(I) metals bind π-ligands by σ-bonding and π-back bonding interactions. These interactions were investigated using bidentate ancillary ligands with electron donating and withdrawing substituents. The π-ligands span from ethylene to larger terminal and internal alkenes and alkynes. Results of X-ray crystallography, NMR, and IR spectroscopy and gas phase experiments show that the binding energies increase in the order AgCuAu and the binding energies are slightly higher for alkynes than for alkenes. Modulation of the electron density at the metal using substituents on the ancillary ligands shows that the π-back bonding interaction plays a dominant role for the binding in the copper and gold complexes.
- Published
- 2022
33. Cationic Gold(II) Complexes: Experimental and Theoretical Study
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Jaya Mehara, Adarsh Koovakattil Surendran, Teun van Wieringen, Deeksha Setia, Cina Foroutan‐Nejad, Michal Straka, Lubomír Rulíšek, and Jana Roithová
- Subjects
Halogens ,Nitrogen ,Cations ,Organic Chemistry ,Spectroscopy and Catalysis ,Gold ,General Chemistry ,Models, Theoretical ,Ligands ,Crystallography, X-Ray ,Copper ,Catalysis - Abstract
Gold(II) complexes are rare and their application for catalysis of chemical transformations is unexplored. The reason is their easy oxidation or reduction to the more stable gold(III) or gold(I) complexes, respectively. We explored the thermodynamics of the formation of the [(L)AuIIX]+ complexes (L = ligand, X = halogen) from their gold(III) precursors and investigated the stability and the spectral properties in the IR and VIS range of the formed gold(II) complexes in the gas phase. The results show that the best ancillary ligands L for stabilizing gaseous [(L)AuIIX]+ complexes are bidentate and tridentate ligands with nitrogen donor atoms. The electronic structure and spectral properties of the investigated gold(II) complexes were correlated with the quantum chemical calculations. The results show that the molecular and electronic structure of the gold(II) complexes as well as their spectroscopic properties are very similar to the analogous stable copper(II) complexes.
- Published
- 2022
34. Experimental techniques and terminology in gas-phase ion spectroscopy
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Aleksandr Pereverzev and Jana Roithová
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Ions ,Spectrum Analysis ,Spectroscopy and Catalysis ,Mass Spectrometry ,Spectroscopy - Abstract
This perspective gives an overview of the action spectroscopy methods for measurements of electronic, vibrational, and rotational spectra of mass-selected ions in the gas phase. We classify and give a short overview of the existing experimental approaches in this field. There is currently a plethora of names used for, essentially, the same techniques. Hence within this overview, we scrutinized the notations and suggested terms to be generally used. The selection was either driven by making the name unique and straightforward or the term being the most broadly used one. We believe that a simplification and a unification of the notation in ion spectroscopy can make this field better accessible for experts outside the mass spectrometry community where the applications of gas-phase action ion spectroscopy can make a large impact.
- Published
- 2022
35. Unmasking the Iron-Oxo Bond of the [(Ligand)Fe-OIAr](2+/+) Complexes
- Author
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Guilherme L. Tripodi and Jana Roithová
- Subjects
Structural Biology ,Spectroscopy and Catalysis ,Spectroscopy - Abstract
Contains fulltext : 253441.pdf (Publisher’s version ) (Open Access) 25 augustus 2022
- Published
- 2022
36. Monitoring Reaction Intermediates to Predict Enantioselectivity Using Mass Spectrometry
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Roelant Hilgers, Sin Yong Teng, Anamarija Briš, Aleksandr Y. Pereverzev, Paul White, Jeroen J. Jansen, and Jana Roithová
- Subjects
asymmetric catalysis ,ion mobility mass spectrometry ,kinetics ,organocatalysis ,reactive intermediates ,Asymmetric Catalysis ,Reactive Intermediates ,Aldehydes ,Food Chemistry ,Organocatalysis ,Stereoisomerism ,General Chemistry ,General Medicine ,Synthetic Organic Chemistry ,Catalysis ,Mass Spectrometry ,Analytical Chemistry ,Kinetics ,Ion Mobility Spectrometry ,Levensmiddelenchemie ,Spectroscopy and Catalysis ,Ethers ,VLAG - Abstract
Enantioselective reactions are at the core of chemical synthesis. Their development mostly relies on prior knowledge, laborious product analysis and post-rationalization by theoretical methods. Here, we introduce a simple and fast method to determine enantioselectivities based on mass spectrometry. The method is based on ion mobility separation of diastereomeric intermediates, formed from a chiral catalyst and prochiral reactants, and delayed reactant labeling experiments to link the mass spectra with the reaction kinetics in solution. The data provide rate constants along the reaction paths for the individual diastereomeric intermediates, revealing the origins of enantioselectivity. Using the derived kinetics, the enantioselectivity of the overall reaction can be predicted. Hence, this method can offer a rapid discovery and optimization of enantioselective reactions in the future. We illustrate the method for the addition of cyclopentadiene (CP) to an α, β-unsaturated aldehyde catalyzed by a diarylprolinol silyl ether.
- Published
- 2022
37. Light-gated binding in double-motorized porphyrin cages
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Roeland J. M. Nolte, Nicolas Vanthuyne, Johannes A. A. W. Elemans, Ben L. Feringa, and Pieter J. Gilissen
- Subjects
Cultural Studies ,Linguistics and Language ,History ,chemistry.chemical_compound ,Chemistry ,Science ,Anthropology ,Spectroscopy and Catalysis ,Photochemistry ,Porphyrin ,Language and Linguistics ,Physical Organic Chemistry - Abstract
Molecular motors change conformation under the influence of light and when attached to host molecules, they may find applications as sensors and switchable catalysts. Here, we present a porphyrin macrocyclic host functionalized with two motor appendages for future catalytic applications. The compound is formed as a mixture of six stereoisomers (three sets of enantiomers), which have been separated by (chiral) chromatography. 1H NMR and chiral spectroscopy revealed that in one set of enantiomers, the two motors interact with the cavity of the host (bound‐bound), whereas in a second set, one interacts and the other one does not (bound‐loose). In the third set, both motors do not interact with the host compound (loose‐loose). The motorized hosts bind guest molecules in the order: (loose‐loose) > (bound‐loose) > (bound‐bound). They can be switched with light to pseudoidentical diastereomers, leading to orthogonal behavior in the light‐gated binding of guest molecules. Although the photoisomerization of the diastereomer set loose‐loose significantly lowers the binding affinity for viologen guests, the opposite is true for the diastereomer set bound‐bound, that is, the binding affinity increases. For the diastereomer set bound‐loose, no influence on guest binding is observed as the effect of photoisomerization on the motors is cancelled out. Key Points We present a porphyrin cage compound with two light‐switchable molecular motors for future catalytic applications The double‐motorized porphyrin cage compound is formed as a mixture of six stereoisomers (three sets of enantiomers), which could be separated, and by photoswitching converted to pseudoidentical stereoisomers The stereoisomers display different binding affinities for guest molecules, which reverse on photoswitching, leading to orthogonal guest binding behavior
- Published
- 2022
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38. 113Cd as a Probe in NMR Studies of Allosteric Host-Guest-Ligand Complexes of Porphyrin Cage Compounds
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Jeroen P. J. Bruekers, Matthijs A. Hellinghuizen, Anne Swartjes, Paul Tinnemans, Paul B. White, Johannes A. A. W. Elemans, and Roeland J. M. Nolte
- Subjects
Organic Chemistry ,Spectroscopy and Catalysis ,Solid State Chemistry ,Synthetic Organic Chemistry ,Physical and Theoretical Chemistry ,Physical Organic Chemistry - Abstract
Contains fulltext : 249263.pdf (Publisher’s version ) (Open Access)
- Published
- 2022
39. Probing Single-Cell Macrophage Polarization and Heterogeneity Using Thermo-Reversible Hydrogels in Droplet-Based Microfluidics
- Author
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B. M. Tiemeijer, M. W. D. Sweep, J. J. F. Sleeboom, K. J. Steps, J. F. van Sprang, P. De Almeida, R. Hammink, P. H. J. Kouwer, A. I. P. M. Smits, J. Tel, Immunoengineering, Biomedical Engineering, Microsystems, Group Den Toonder, Biomedical Materials and Chemistry, Soft Tissue Biomech. & Tissue Eng., ICMS Affiliated, and ICMS Core
- Subjects
Histology ,cytokine secretion ,Systems Chemistry ,Microfluidics ,Biomedical Engineering ,Macrophage polarization ,Bioengineering ,PHENOTYPE ,Single-cell analysis ,cellular heterogeneity ,polyisocyanide ,Spectroscopy and Catalysis ,single-cell analysis ,Viability assay ,MODULATION ,PLASTICITY ,high-throughput ,Original Research ,Science & Technology ,droplet microfluidics ,Chemistry ,flow cytometry ,Bioengineering and Biotechnology ,Juxtacrine signalling ,Multidisciplinary Sciences ,Biotechnology & Applied Microbiology ,Cell culture ,inflammation ,Self-healing hydrogels ,Biophysics ,Science & Technology - Other Topics ,Cytokine secretion ,Life Sciences & Biomedicine ,TP248.13-248.65 ,Biotechnology ,RESPONSES - Abstract
Human immune cells intrinsically exist as heterogenous populations. To understand cellular heterogeneity, both cell culture and analysis should be executed with single-cell resolution to eliminate juxtacrine and paracrine interactions, as these can lead to a homogenized cell response, obscuring unique cellular behavior. Droplet microfluidics has emerged as a potent tool to culture and stimulate single cells at high throughput. However, when studying adherent cells at single-cell level, it is imperative to provide a substrate for the cells to adhere to, as suspension culture conditions can negatively affect biological function and behavior. Therefore, we combined a droplet-based microfluidic platform with a thermo-reversible polyisocyanide (PIC) hydrogel, which allowed for robust droplet formation at low temperatures, whilst ensuring catalyzer-free droplet gelation and easy cell recovery after culture for downstream analysis. With this approach, we probed the heterogeneity of highly adherent human macrophages under both pro-inflammatory M1 and anti-inflammatory M2 polarization conditions. We showed that co-encapsulation of multiple cells enhanced cell polarization compared to single cells, indicating that cellular communication is a potent driver of macrophage polarization. Additionally, we highlight that culturing single macrophages in PIC hydrogel droplets displayed higher cell viability and enhanced M2 polarization compared to single macrophages cultured in suspension. Remarkably, combining phenotypical and functional analysis on single cultured macrophages revealed a subset of cells in a persistent M1 state, which were undetectable in conventional bulk cultures. Taken together, combining droplet-based microfluidics with hydrogels is a versatile and powerful tool to study the biological function of adherent cell types at single-cell resolution with high throughput. ispartof: FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY vol:9 ispartof: location:Switzerland status: published
- Published
- 2021
40. A photoswitchable catalyst for the enantiodivergent epoxidation of alkenes
- Author
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Gilissen, P.J. and Elemans, J.A.A.W.
- Subjects
Spectroscopy and Catalysis ,Physical Organic Chemistry - Abstract
Item does not contain fulltext
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- 2022
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41. Monoaurated vs. diaurated intermediates: causality or independence?†
- Author
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Jana Roithová, Mariarosa Anania, Juraj Jašík, Elena Shcherbachenko, Jan Zelenka, and Lucie Jašíková
- Subjects
chemistry.chemical_classification ,Reaction mechanism ,Ketone ,010405 organic chemistry ,Chemistry ,Kinetics ,Photodissociation ,Protonation ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,3. Good health ,0104 chemical sciences ,Catalysis ,Reaction rate ,Kinetic isotope effect ,Spectroscopy and Catalysis - Abstract
Diaurated intermediates of gold-catalysed reactions have been a long-standing subject of debate. Although diaurated complexes were regarded as a drain of active monoaurated intermediates in catalytic cycles, they were also identified as the products of gold–gold cooperation in dual–activation reactions. This study shows investigation of intermediates in water addition to alkynes catalysed by [(IPr)Au(CH3CN)(BF4)]. Electrospray ionisation mass spectrometry (ESI-MS) allowed us to detect both monoaurated and diaurated complexes in this reaction. Infrared photodissociation spectra of the trapped complexes show that the structure of the intermediates corresponds to α-gold ketone intermediates protonated or aurated at the oxygen atom. Delayed reactant labelling experiments provided the half life of the intermediates in reaction of 1-phenylpropyne (∼7 min) and the kinetic isotope effects for hydrogen introduction to the carbon atom (KIE ∼ 4–6) and for the protodeauration (KIE ∼ 2). The results suggest that the ESI-MS detected monoaurated and diaurated complexes report on species with a very similar or the same kinetics in solution. Kinetic analysis of the overall reaction showed that the reaction rate is first-order dependent on the concentration of the gold catalyst. Finally, all results are consistent with the reaction mechanism proceeding via monoaurated neutral α-gold ketone intermediates only., Reaction kinetics and detected α-gold ketone intermediates reveal that gold-mediated hydration of alkynes does not rely on dual activation.
- Published
- 2019
42. Chemoselectivity in the Oxidation of Cycloalkenes with a Non-Heme Iron(IV)-Oxo-Chloride Complex: Epoxidation vs. Hydroxylation Selectivity
- Author
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Martin Srnec, Ilaria Gamba, Miquel Costas, Thibault Terencio, Erik Andris, and Jana Roithová
- Subjects
Allylic rearrangement ,Cyclohexene ,Epoxidation ,010402 general chemistry ,Oxidació ,Iron compounds ,DFT calculations ,01 natural sciences ,Medicinal chemistry ,Reaccions químiques ,Hydroxylation ,chemistry.chemical_compound ,Structural Biology ,Chemical reactions ,Oxidation ,Focus: Honoring Helmut Schwarzʻs Election to the National Academy of Sciences: Research Article ,Gas-phase reactions ,Spectroscopy and Catalysis ,Reactivity (chemistry) ,Chemoselectivity ,Spectroscopy ,Density functionals ,Funcional de densitat, Teoria del ,010401 analytical chemistry ,Solvation ,Ferro -- Compostos ,Iron complexes ,Transition state ,3. Good health ,0104 chemical sciences ,chemistry ,Cycloheptene ,C–H activation - Abstract
We report and analyze chemoselectivity in the gas phase reactions of cycloalkenes (cyclohexene, cycloheptene, cis-cyclooctene, 1,4-cyclohexadiene) with a non-heme iron(IV)-oxo complex [(PyTACN)Fe(O)(Cl)]+, which models the active species in iron-dependent halogenases. Unlike in the halogenases, we did not observe any chlorination of the substrate. However, we observed two other reaction pathways: allylic hydrogen atom transfer (HAT) and alkene epoxidation. The HAT is clearly preferred in the case of 1,4-cyclohexadiene, both pathways have comparable reaction rates in reaction with cyclohexene, and epoxidation is strongly favored in reactions with cycloheptene and cis-cyclooctene. This preference for epoxidation differs from the reactivity of iron(IV)-oxo complexes in the condensed phase, where HAT usually prevails. To understand the observed selectivity, we analyze effects of the substrate, spin state, and solvation. Our DFT and CASPT2 calculations suggest that all the reactions occur on the quintet potential energy surface. The DFT-calculated energies of the transition states for the epoxidation and hydroxylation pathways explain the observed chemoselectivity. The SMD implicit solvation model predicts the relative increase of the epoxidation barriers with solvent polarity, which explains the clear preference of HAT in the condensed phase. Electronic supplementary material The online version of this article (10.1007/s13361-019-02251-1) contains supplementary material, which is available to authorized users.
- Published
- 2019
43. Characterized cis-FeV(O)(OH) intermediate mimics enzymatic oxidations in the gas phase
- Author
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Erik Andris, Jana Roithová, Rafael Navrátil, Margarida Borrell, and Miquel Costas
- Subjects
0301 basic medicine ,Oxygenase ,Stereochemistry ,Iron ,Science ,Catalitzadors ,Reactive intermediate ,General Physics and Astronomy ,Context (language use) ,02 engineering and technology ,Article ,Catalysis ,General Biochemistry, Genetics and Molecular Biology ,Bioinorganic chemistry ,Chemistry, Physical and theoretical ,03 medical and health sciences ,Spectroscopy and Catalysis ,Reactivity (chemistry) ,lcsh:Science ,chemistry.chemical_classification ,Multidisciplinary ,Catalysts ,General Chemistry ,Química bioinorgànica ,021001 nanoscience & nanotechnology ,3. Good health ,respiratory tract diseases ,030104 developmental biology ,Enzyme ,chemistry ,Dihydroxylation ,Oxygenases ,lcsh:Q ,0210 nano-technology ,Oxidation-Reduction ,Iron Compounds ,Fisicoquímica - Abstract
FeV(O)(OH) species have long been proposed to play a key role in a wide range of biomimetic and enzymatic oxidations, including as intermediates in arene dihydroxylation catalyzed by Rieske oxygenases. However, the inability to accumulate these intermediates in solution has thus far prevented their spectroscopic and chemical characterization. Thus, we use gas-phase ion spectroscopy and reactivity analysis to characterize the highly reactive [FeV(O)(OH)(5tips3tpa)]2+ (32+) complex. The results show that 32+ hydroxylates C–H bonds via a rebound mechanism involving two different ligands at the Fe center and dihydroxylates olefins and arenes. Hence, this study provides a direct evidence of FeV(O)(OH) species in non-heme iron catalysis. Furthermore, the reactivity of 32+ accounts for the unique behavior of Rieske oxygenases. The use of gas-phase ion characterization allows us to address issues related to highly reactive intermediates that other methods are unable to solve in the context of catalysis and enzymology., FeV(O)(OH) species have long been thought to play a role in a range of enzymatic oxidations, but their characterization has remained elusive. Here, using gas-phase ion spectroscopy, the authors characterize an FeV(O)(OH) species and find that its reactivity mimics that of Rieske oxygenases.
- Published
- 2019
44. Tagging fullerene ions with helium in a cryogenic quadrupole trap
- Author
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Dieter Gerlich, Juraj Jašík, and Jana Roithová
- Subjects
Fullerene ,Infrared ,Chemistry ,010401 analytical chemistry ,chemistry.chemical_element ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,7. Clean energy ,Spectral line ,0104 chemical sciences ,Ion ,Quadrupole ,Spectroscopy and Catalysis ,Ion trap ,Physical and Theoretical Chemistry ,Atomic physics ,Ternary operation ,Instrumentation ,Spectroscopy ,Helium - Abstract
Helium tagging of charged C60q+ ions (q = 1–3) has been used for measuring electronic and infrared gas phase spectra, allowing astronomers to improve the identification of fullerenes in space. Here, we present a detailed study of the attachment of He to cold mass selected fullerene ions. Experiments were performed in the temperature variable radio frequency (rf) ion trap ISORI at high He densities and a few K. For all three charge states, the ternary rate coefficients for forming He-C60q+ are below 10−31 cm6s–1 and all three show temperature dependences, proportional to exp(-T/T0) with T0.
- Published
- 2019
45. Controlling internal degrees: general discussion
- Author
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Jana Roithová, Roland Wester, Sotiris S. Xantheas, Stephan Schlemmer, Mark A. Johnson, Steven F. Daly, Otto Dopfer, Marie-Pierre Gaigeot, Jan R. R. Verlet, Anouk M. Rijs, Daniel M. Neumark, Christopher J. Johnson, Chin-wen Chou, Jack Simons, Xue-Bin Wang, Laura McCaslin, L. Ellis-Gibbings, Adam J. Trevitt, Mark H. Stockett, Martin Mayer, Anne B. McCoy, Anna I. Krylov, Thomas R. Rizzo, Jos Oomens, Benny Gerber, Peter J. Sarre, Knut R. Asmis, Ivan Avdonin, Stefan Willitsch, Valérie Gabelica, Kenneth D. Jordan, Martin K. Beyer, Michael Gatchell, Musahid Ahmed, Evan J. Bieske, Sana Bougueroua, and Milan Ončák
- Subjects
visible photodissociation spectra ,ab-initio ,FELIX Molecular Structure and Dynamics ,spectroscopy ,business.industry ,Computer science ,water ,temperature ,dynamics ,Data science ,p-hydroxybenzoic acid ,rhodamine ions ,Text mining ,Spectroscopy and Catalysis ,molecules ,clusters ,Physical and Theoretical Chemistry ,business - Abstract
Contains fulltext : 214969.pdf (Publisher’s version ) (Closed access)
- Published
- 2019
- Full Text
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46. Ion spectroscopy in methane activation
- Author
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Joost M. Bakker and Jana Roithová
- Subjects
0301 basic medicine ,Metal ions in aqueous solution ,Carbyne ,Reaction intermediate ,Photochemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Methane ,Mass Spectrometry ,Analytical Chemistry ,Ion ,03 medical and health sciences ,chemistry.chemical_compound ,Spectroscopy and Catalysis ,Molecule ,Spectroscopy ,FELIX Condensed Matter Physics ,Ions ,Chemistry ,Spectrum Analysis ,010401 analytical chemistry ,Condensed Matter Physics ,0104 chemical sciences ,Characterization (materials science) ,030104 developmental biology ,Metals - Abstract
This review is devoted to ion spectroscopy studies of complexes relevant for the understanding of methane activation with metal ions and clusters. Methane activation starts with the formation of a complex with a metal ion. The degree of the interaction between an intact methane molecule and the ion can be monitored by the perturbations of C-H stretch vibrations in the methane molecule. Binding mediated by the electrostatic interaction results in a η3 type coordination of methane. In contrast, binding governed by orbital interactions results in a η2 type coordination of methane. We further review the spectroscopic characterization of activation products of metal-methane reactions, such as the metal-carbene and carbyne products resulting from the interaction of selected 5d metals with methane. The focus of recent research in the field has shifted towards the investigation of interactions between methane and metal clusters. We show examples highlighting that metal clusters can be more reactive in methane activation reactions.
- Published
- 2021
47. Gold(I) and Silver(I) pi-Complexes with Unsaturated Hydrocarbons
- Author
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Juraj Jašík, Petr Motloch, Jana Roithová, Motloch, Petr [0000-0002-3118-4119], Roithová, Jana [0000-0001-5144-0688], and Apollo - University of Cambridge Repository
- Subjects
34 Chemical Sciences ,010405 organic chemistry ,Ligand ,Organic Chemistry ,Photodissociation ,Binding energy ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Bond-dissociation energy ,Article ,0104 chemical sciences ,3402 Inorganic Chemistry ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,3406 Physical Chemistry ,Spectroscopy and Catalysis ,Density functional theory ,Physical and Theoretical Chemistry ,Alkadienes ,Acetonitrile ,Phosphine - Abstract
Gold π-complexes have been studied largely in the past 2 decades because of their role in gold-catalyzed reactions. We report an experimental and theoretical investigation of the interaction between a wide range of unsaturated hydrocarbons (alkanes, alkynes, alkadienes, and allenes) and triphenylphosphine-gold(I), triphenylphosphine-silver(I), and acetonitrile-silver(I) cations. The bond dissociation energies of these complexes were determined by mass spectrometry collision-induced dissociations and their structures were studied by density functional theory calculations and infrared photodissociation spectroscopy. The results show that with the same phosphine ligand, gold binds stronger to the π-ligands than silver and thereby activates the unsaturated bond more effectively. Ligand exchange of phosphine by acetonitrile at the silver complexes increases the binding energy as well as the activation of the π-ligands. We also show that the substitution of an unsaturated bond is more important than the bond type.
- Published
- 2021
48. Multi-epoch searches for relativistic binary pulsars and fast transients in the Galactic Centre
- Author
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Kang Liu, Gregory Desvignes, Luciano Rezzolla, Michael Kramer, Heino Falcke, D. J. Champion, Kejia Lee, Laura Spitler, Bernd Klein, R. P. Eatough, Robert Wharton, Pablo Torne, Ramesh Karuppusamy, Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Astronomy ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Magnetar ,01 natural sciences ,Radio telescope ,stars: magnetars ,Pulsar ,Millisecond pulsar ,pulsars: general ,0103 physical sciences ,Spectroscopy and Catalysis ,education ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,education.field_of_study ,Supermassive black hole ,010308 nuclear & particles physics ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy: centre ,Neutron star ,Sagittarius A ,13. Climate action ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
The high stellar density in the central parsecs around the Galactic Centre makes it a seemingly favourable environment for finding relativistic binary pulsars. These include pulsars orbiting other neutron stars, stellar-mass black holes or the central supermassive black hole, Sagittarius A*. Here we present multi-epoch pulsar searches of the Galactic Centre at four observing frequencies, (4.85, 8.35, 14.6 18.95) GHz, using the Effelsberg 100-m radio telescope. Observations were conducted one year prior to the discovery of, and during monitoring observations of, the Galactic Centre magnetar PSR J1745-2900. Our data analysis features acceleration searches on progressively shorter time series to maintain sensitivity to relativistic binary pulsars. The multi-epoch observations increase the likelihood of discovering transient or nulling pulsars, or ensure orbital phases are observed at which acceleration search methods work optimally. In ~147 h of separate observations, no previously undiscovered pulsars have been detected. Through calibration observations, we conclude this might be due to insufficient instantaneous sensitivity; caused by the intense continuum emission from the Galactic Centre, its large distance and, at higher frequencies, the aggregate effect of steep pulsar spectral indices and atmospheric contributions to the system temperature. Additionally we find that for millisecond pulsars in wide circular orbits ~, 17 pages, 12 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society
- Published
- 2021
- Full Text
- View/download PDF
49. Combining Mechanical Tuneability with Function: Biomimetic Fibrous Hydrogels with Nanoparticle Crosslinkers
- Author
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Wen Chen and Paul H. J. Kouwer
- Subjects
Biomaterials ,Materials science ,Nanocomposite hydrogels ,Systems Chemistry ,Self-healing hydrogels ,Electrochemistry ,Spectroscopy and Catalysis ,Nanoparticle ,Nanotechnology ,Condensed Matter Physics ,Function (biology) ,Electronic, Optical and Magnetic Materials - Abstract
Contains fulltext : 240256.pdf (Publisher’s version ) (Open Access)
- Published
- 2021
50. Magnetic Stiffening in 3D Cell Culture Matrices
- Author
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Hans Engelkamp, Jyoti Kumari, Paul H. J. Kouwer, Ying Zhang, and Wen Chen
- Subjects
Materials science ,Letter ,Systems Chemistry ,Cell Culture Techniques ,Bioengineering ,Cell morphology ,Matrix (mathematics) ,3D cell culture ,Magnetics ,adaptive hydrogels ,Soft Condensed Matter and Nanomaterials ,magnetic iron oxide nanoparticles ,Spectroscopy and Catalysis ,General Materials Science ,Composite material ,mammary epithelium ,extracellular matrices ,Mechanical Engineering ,Magnetic Phenomena ,ferrogels ,Hydrogels ,General Chemistry ,Condensed Matter Physics ,equipment and supplies ,Magnetic field ,Stiffening ,Magnet ,Self-healing hydrogels ,Nanorod ,Stress, Mechanical - Abstract
The mechanical environment of a cell is not constant. This dynamic behavior is exceedingly difficult to capture in (synthetic) in vitro matrices. This paper describes a novel, highly adaptive hybrid hydrogel composed of magnetically sensitive magnetite nanorods and a stress-responsive synthetic matrix. Nanorod rearrangement after application of (small) magnetic fields induces strain in the network, which results in a strong (over 10-fold) stiffening even at minimal (2.5 wt %) nanorod concentrations. Moreover, the stiffening mechanism yields a fast and fully reversible response. In the manuscript, we quantitatively analyze that forces generated by the particles are comparable to cellular forces. We demonstrate the value of magnetic stiffening in a 3D MCF10A epithelial cell experiment, where simply culturing on top of a permanent magnet gives rise to changes in the cell morphology. This work shows that our hydrogels are uniquely suited as 3D cell culture systems with on-demand adaptive mechanical properties.
- Published
- 2021
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