1
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Kubis C, König M, Leidecker BN, Selent D, Schröder H, Sawall M, Baumann W, Spannenberg A, Brächer A, Neymeyr K, Franke R, Börner A. Interplay between Catalyst Complexes and Dormant States: In Situ Spectroscopic Investigations on a Catalyst System for Alkene Hydroformylation. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Affiliation(s)
- Christoph Kubis
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
| | - Matthias König
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
- Evonik Operations GmbH, Paul-Baumann-Street 1, 45772 Marl, Germany
| | - Benedict N. Leidecker
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
| | - Detlef Selent
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
| | - Henning Schröder
- University of Rostock, Institute of Mathematics, Ulmenstraße 59, 18057 Rostock, Germany
| | - Mathias Sawall
- University of Rostock, Institute of Mathematics, Ulmenstraße 59, 18057 Rostock, Germany
| | - Wolfgang Baumann
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
| | - Anke Spannenberg
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
| | | | - Klaus Neymeyr
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
- University of Rostock, Institute of Mathematics, Ulmenstraße 59, 18057 Rostock, Germany
| | - Robert Franke
- Evonik Operations GmbH, Paul-Baumann-Street 1, 45772 Marl, Germany
- Chair for Theoretical Chemistry, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Armin Börner
- Leibniz-Institute for Catalysis e.V., Albert-Einstein-Street 29a, 18059 Rostock, Germany
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2
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Metzger C, Dolai R, Reh S, Kelm H, Schmitz M, Oelkers B, Sawall M, Neymeyr K, Krüger HJ. A new Type of Valence Tautomerism in Cobalt Dioxolene Complexes - Temperature-Induced Transition from a Cobalt(III) Catecholate to a Low-Spin Cobalt(II) Semiquinonate State. Chemistry 2023; 29:e202300091. [PMID: 36808779 DOI: 10.1002/chem.202300091] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023]
Abstract
The synthesis and characterization of the monocationic cobalt(III) catecholate complex [Co(L-N4 t Bu2)(Cl2cat)]+ (L-N4 t Bu2 = N,N'-Di-tert.-butyl-2,11-diaza[3.3](2,6)pyridinophane, Cl2cat2- = 4,5-dichlorocatecholate) are presented. The complex exhibits valence tautomeric properties in solution; but, in contrast to the usually observed conversion from a cobalt(III) catecholate to a high-spin cobalt(II) semiquinonate state, valence tautomerism of [Co(L-N4 t Bu2)(Cl2cat)]+ leads to the formation of a low-spin cobalt(II) semiquinonate complex upon raising the temperature. This new type of valence tautomerism for a cobalt dioxolene complex has been unambiguously established by a detailed spectroscopic investigation using variable-temperature NMR, IR and UV-Vis-NIR spectroscopy. Determination of the enthalpies and entropies characterizing the valence tautomeric equilibria in various solutions shows that the influence of the solvent is almost exclusively entropic.
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Affiliation(s)
- Christoph Metzger
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Ramapada Dolai
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Sabine Reh
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Harald Kelm
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Markus Schmitz
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Benjamin Oelkers
- RPTU: Rheinland-Pfalzische Technische Universitat Kaiserslautern-Landau, Department of Chemistry, GERMANY
| | - Mathias Sawall
- Universität Rostock Mathematisch-Naturwissenschaftliche Fakultät: Universitat Rostock Mathematisch-Naturwissenschaftliche Fakultat, Mathematik, GERMANY
| | - Klaus Neymeyr
- Universität Rostock Mathematisch-Naturwissenschaftliche Fakultät: Universitat Rostock Mathematisch-Naturwissenschaftliche Fakultat, Mathematik, GERMANY
| | - Hans-Jörg Krüger
- Technische Universität Kaiserslautern, Department of Chemistry, Erwin-Schrödinger Str Gebäude 54, 67663, Kaiserslautern, GERMANY
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3
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Sawall M, Ruckebusch C, Beese M, Francke R, Prudlik A, Neymeyr K. An active constraint approach to identify essential spectral information in noisy data. Anal Chim Acta 2022; 1233:340448. [DOI: 10.1016/j.aca.2022.340448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/24/2022] [Indexed: 11/01/2022]
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4
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Meinhardt D, Schröder H, Hellwig J, Steimers E, Friebel A, Beweries T, Sawall M, von Harbou E, Neymeyr K. Model-based signal tracking in the quantitative analysis of time series of NMR spectra. J Magn Reson 2022; 339:107212. [PMID: 35398778 DOI: 10.1016/j.jmr.2022.107212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 06/14/2023]
Abstract
Hard modeling of NMR spectra by Gauss-Lorentz peak models is an effective way for dimensionality reduction. In this manner high-dimensional measured data are reduced to low-dimensional information as peak centers, amplitudes or peak widths. For time series of spectra these parameters can be assumed to be smooth functions in time. We suggest to model these time-dependent parameter functions by cubic spline functions, which makes a stable quantitative analysis of NMR series possible even for crossing, highly overlapping peaks. Applications are presented for the batch distillation of methanol and diethylamine, and the reaction of acetic anhydride with 2-propanol.
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Affiliation(s)
- Denise Meinhardt
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Henning Schröder
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Jan Hellwig
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany
| | - Ellen Steimers
- Technische Universität Kaiserslautern, Laboratory of Engineering Thermodynamics (LTD), 67663 Kaiserslautern, Germany
| | - Anne Friebel
- Technische Universität Kaiserslautern, Laboratory of Engineering Thermodynamics (LTD), 67663 Kaiserslautern, Germany
| | | | - Mathias Sawall
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany
| | - Erik von Harbou
- Technische Universität Kaiserslautern, Laboratory of Reaction and Fluid Process Engineering, 67663 Kaiserslautern, Germany
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V., 18059 Rostock, Germany.
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5
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Lindenau K, Jannsen N, Rippke M, Al Hamwi H, Selle C, Drexler HJ, Spannenberg A, Sawall M, Neymeyr K, Heller D, Reiß F, Beweries T. Mechanistic insights into dehydrocoupling of amine boranes using dinuclear zirconocene complexes. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00531f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic dehydrocoupling of H3B·NMe2H using Cp2Zr(Cl)(μ-Me3SiC3SiMe3)Zr(Cl)Cp2 (1)/MeLi was studied. Spectroscopic monitoring and stoichiometric experiments show the formation and interconversion of several catalytically active Zr species.
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Affiliation(s)
| | - Nora Jannsen
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | - Mirko Rippke
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | | | - Carmen Selle
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | | | | | - Mathias Sawall
- Institut für Mathematik
- Universität Rostock
- 18055 Rostock
- Germany
| | - Klaus Neymeyr
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
- Institut für Mathematik
- Universität Rostock
| | - Detlef Heller
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
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6
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Vali Zade S, Neymeyr K, Abdollahi H, Sawall M. Characterization of the unimodality constraint as an effective chemistry-based condition in resolving of chemical processes data. Microchem J 2021. [DOI: 10.1016/j.microc.2020.105615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Overbeck V, Schröder H, Bonsa AM, Neymeyr K, Ludwig R. Insights into the translational and rotational dynamics of cations and anions in protic ionic liquids by means of NMR fast-field-cycling relaxometry. Phys Chem Chem Phys 2021; 23:2663-2675. [PMID: 33480888 DOI: 10.1039/d0cp05440b] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the translational and rotational dynamics of cations and anions in hydrogen bonded protic ionic liquids (PIls) is still a challenge. In this study, we determine self-diffusion coefficients and rotational correlation times of both ions in triethylammonium based PILs by means of NMR Fast-Field-Cycling (FFC) relaxometry. Global fits of 1H and 19F nuclear magnetic relaxation dispersion (NMRD) curves allowed proper separation into intra and inter molecular relaxation rates for both NMR sensitive nuclei and thus a reliable description of translational and rotational motion for both ions individually. The diffusion coefficients of the cations are in the order of 6 × 10-11 m2 s-1 at room temperature and about 50 per cent larger than those of the anions. The diffusion coefficients of cations and anions in both PILs were compared with those we derived from applying an universal dispersion power law and those known from pulsed field gradient (PFG) NMR studies. Considering the Nernst-Einstein equation, molar conductivities were calculated from cationic and anionic diffusion coefficients and related to directly measured molar conductivities, allowing the determination of the degree of dissociation. The rotational correlation times τR ranging from 50 ps up to 2 ns as a function of temperature were compared with those obtained from high-field NMR quadrupolar relaxation time measurements addressing explicitly the rotation of the NH vector and giving insights into the acidic proton mobility. The Stokes-Einstein and Stokes-Einstein-Debye relations were applied to relate the diffusion coefficients and rotational correlation times to the macroscopic bulk viscosity. The results were also discussed with respect to the archetypical PIL ethylammonium nitrate.
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Affiliation(s)
- Viviane Overbeck
- Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany. and Physical and Theoretical Chemistry, Department of Chemistry, University of Rostock, Dr-Lorenz-Weg 2, 18059 Rostock, Germany
| | - Henning Schröder
- Department of Mathematics, University of Rostock, Ulmenstr. 69, 18057 Rostock, Germany
| | - Anne-Marie Bonsa
- Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany. and Physical and Theoretical Chemistry, Department of Chemistry, University of Rostock, Dr-Lorenz-Weg 2, 18059 Rostock, Germany
| | - Klaus Neymeyr
- Department of Mathematics, University of Rostock, Ulmenstr. 69, 18057 Rostock, Germany
| | - Ralf Ludwig
- Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany. and Physical and Theoretical Chemistry, Department of Chemistry, University of Rostock, Dr-Lorenz-Weg 2, 18059 Rostock, Germany and Leibniz Institute for Catalysis e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
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8
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Overbeck V, Golub B, Schröder H, Appelhagen A, Paschek D, Neymeyr K, Ludwig R. Probing relaxation models by means of Fast Field-Cycling relaxometry, NMR spectroscopy and molecular dynamics simulations: Detailed insight into the translational and rotational dynamics of a protic ionic liquid. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114207] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Schröder H, Ruckebusch C, Brächer A, Sawall M, Meinhardt D, Kubis C, Mostafapour S, Börner A, Franke R, Neymeyr K. Reaction rate ambiguities for perturbed spectroscopic data: Theory and implementation. Anal Chim Acta 2020; 1137:170-180. [PMID: 33153600 DOI: 10.1016/j.aca.2020.08.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 10/23/2022]
Abstract
The analysis of reaction systems and their kinetic modeling is important for both exploratory research and process design. Multivariate curve resolution (MCR) methods are state-of-the-art tools for the analysis of spectral series, but are also affected by an unavoidable solution ambiguity that impacts the obtained concentration profiles, spectra and model parameters. These uncertainties depend on the underlying model and the magnitude of the measurement perturbations. We present a general theoretical approach together with a computational method for the analysis of the solution ambiguity underlying arbitrary kinetic models. The main idea is to determine all those model parameters for which the corresponding pure component factorizations satisfy all given constraints within small error tolerances. This makes it possible to determine bands of concentration profiles and spectra that reflect the underlying ambiguity and circumscribes the potential reliability of MCR solutions. False conclusions on the uniqueness of a solution can be prevented. The procedure can be applied as a post-processing step to MCR methods as MCR-ALS, ReactLab or others. The Matlab program code is freely accessible and includes not only the proposed ambiguity analysis but also an MCR hard-modeling approach. Application studies are presented for two experimental data sets, namely for UV/Vis spectra on the relaxation of a photoexcited state of benzophenone and for Raman spectra on an aldehyde formation process.
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Affiliation(s)
- Henning Schröder
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057, Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Straße 29a, 18059, Rostock, Germany.
| | - Cyril Ruckebusch
- U Lille, CNRS, LASIRE, Laboratoire de Spectroscopie pour Les Interactions, La Réactivité et L'environnement, F-59000, Lille, France
| | - Alexander Brächer
- Evonik Performance Materials GmbH, Paul-Baumann Straße 1, 45772, Marl, Germany
| | - Mathias Sawall
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057, Rostock, Germany
| | - Denise Meinhardt
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057, Rostock, Germany
| | - Christoph Kubis
- Leibniz-Institut für Katalyse, Albert-Einstein-Straße 29a, 18059, Rostock, Germany
| | - Sara Mostafapour
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057, Rostock, Germany; Department of Chemistry, Shiraz University, 71454, Shiraz, Iran
| | - Armin Börner
- Leibniz-Institut für Katalyse, Albert-Einstein-Straße 29a, 18059, Rostock, Germany
| | - Robert Franke
- Evonik Performance Materials GmbH, Paul-Baumann Straße 1, 45772, Marl, Germany; Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057, Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Straße 29a, 18059, Rostock, Germany
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10
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Sawall M, Rüdt M, Hubbuch J, Neymeyr K. On the analysis of chromatographic biopharmaceutical data by curve resolution techniques in the framework of the area of feasible solutions. J Chromatogr A 2020; 1627:461420. [PMID: 32823115 DOI: 10.1016/j.chroma.2020.461420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 10/23/2022]
Abstract
Monitoring preparative protein chromatographic steps by in-line spectroscopic tools or fraction analytics results in medium or large sized data matrices. Multivariate Curve Resolution (MCR) serve to compute or to estimate the concentration values of the pure components only from these data matrices. However, MCR methods often suffer from an inherent solution ambiguity which underlies the factorization problem. The typical unimodality of the chromatographic profiles of pure components can support the chemometric analysis. Here we present the pure components estimation process within the framework of the area of feasible solutions, which is a systematic approach to represent the range of all possible solutions. The unimodality constraint in combination with Pareto optimization is shown to be an effective method for the pure component calculation. Applications are presented for chromatograms on a model protein mixture containing ribonuclease A, cytochrome c and lysozyme and on a two-dimensional chromatographic separation of a monoclonal antibody from its aggregate species. The root mean squared errors of the first case study are 0.0373, 0.0529 and 0.0380 g/L compared to traditional off-line analytics. The second case study illustrates the potential of recovering hidden components with MCR from off-line reference analytics.
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Affiliation(s)
- Mathias Sawall
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany.
| | - Matthias Rüdt
- Karlsruhe Institute of Technology, Institute of Engineering in Life Sciences, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
| | - Jürgen Hubbuch
- Karlsruhe Institute of Technology, Institute of Engineering in Life Sciences, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
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11
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Lange H, Schröder H, Oberem E, Villinger A, Rabeah J, Ludwig R, Neymeyr K, Seidel WW. Facile Synthesis of a Stable Side-on Phosphinyne Complex by Redox Driven Intramolecular Cyclisation. Chemistry 2020; 26:11492-11502. [PMID: 32181544 PMCID: PMC7540294 DOI: 10.1002/chem.201905750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/08/2020] [Indexed: 11/23/2022]
Abstract
Alkyne complexes with vicinal substitution by a Lewis acid and a Lewis base at the coordinated alkyne are prospective frustrated Lewis pairs exhibiting a particular mutual distance and, hence, a specific activation potential. In this contribution, investigations on the generation of a WII alkyne complex bearing a phosphine as Lewis base and a carbenium group as Lewis acid are presented. Independently on potential substrates added, an intramolecular cyclisation product was always isolated. A subsequent deprotonation step led to an unprecedented side-on λ5 -phosphinyne complex, which is interpreted as highly zwitterionic according to visible absorption spectroscopy supported by TD-DFT. Low-temperature 31 P NMR and EPR spectroscopic measurements combined with time-dependent IR-spectroscopic monitoring provided insights in the mechanism of the cyclisation reaction. Decomposition of the multicomponent IR spectra by multivariate curve resolution and a kinetic hard-modelling approach allowed the derivation of kinetic parameters. Assignment of the individual IR spectra to potential intermediates was provided by DFT calculations.
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Affiliation(s)
- Helge Lange
- Institut für ChemieUniversität RostockAlbert-Einstein-Str. 3a18059RostockGermany
| | - Henning Schröder
- Institut für MathematikUniversität RostockUlmenstraße 6918057RostockGermany
| | - Elisabeth Oberem
- Institut für ChemieUniversität RostockAlbert-Einstein-Str. 3a18059RostockGermany
| | - Alexander Villinger
- Institut für ChemieUniversität RostockAlbert-Einstein-Str. 3a18059RostockGermany
| | - Jabor Rabeah
- Leibniz-Institut für Katalyse e.V.Albert-Einstein-Straße 29a18059RostockGermany
| | - Ralf Ludwig
- Institut für ChemieUniversität RostockAlbert-Einstein-Str. 3a18059RostockGermany
- Leibniz-Institut für Katalyse e.V.Albert-Einstein-Straße 29a18059RostockGermany
| | - Klaus Neymeyr
- Institut für MathematikUniversität RostockUlmenstraße 6918057RostockGermany
- Leibniz-Institut für Katalyse e.V.Albert-Einstein-Straße 29a18059RostockGermany
| | - Wolfram W. Seidel
- Institut für ChemieUniversität RostockAlbert-Einstein-Str. 3a18059RostockGermany
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12
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Roeters SJ, Sawall M, Eskildsen CE, Panman MR, Tordai G, Koeman M, Neymeyr K, Jansen J, Smilde AK, Woutersen S. Unraveling VEALYL Amyloid Formation Using Advanced Vibrational Spectroscopy and Microscopy. Biophys J 2020; 119:87-98. [PMID: 32562617 DOI: 10.1016/j.bpj.2020.05.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 04/23/2020] [Accepted: 05/11/2020] [Indexed: 12/19/2022] Open
Abstract
Intermediate species are hypothesized to play an important role in the toxicity of amyloid formation, a process associated with many diseases. This process can be monitored with conventional and two-dimensional infrared spectroscopy, vibrational circular dichroism, and optical and electron microscopy. Here, we present how combining these techniques provides insight into the aggregation of the hexapeptide VEALYL (Val-Glu-Ala-Leu-Tyr-Leu), the B-chain residue 12-17 segment of insulin that forms amyloid fibrils (intermolecularly hydrogen-bonded β-sheets) when the pH is lowered below 4. Under such circumstances, the aggregation commences after approximately an hour and continues to develop over a period of weeks. Singular value decompositions of one-dimensional and two-dimensional infrared spectroscopy spectra indicate that intermediate species are formed during the aggregation process. Multivariate curve resolution analyses of the one and two-dimensional infrared spectroscopy data show that the intermediates are more fibrillar and deprotonated than the monomers, whereas they are less ordered than the final fibrillar structure that is slowly formed from the intermediates. A comparison between the vibrational circular dichroism spectra and the scanning transmission electron microscopy and optical microscope images shows that the formation of mature fibrils of VEALYL correlates with the appearance of spherulites that are on the order of several micrometers, which give rise to a "giant" vibrational circular dichroism effect.
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Affiliation(s)
- Steven J Roeters
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, the Netherlands.
| | - Mathias Sawall
- Institut für Mathematik, Universität Rostock, Rostock, Germany
| | - Carl E Eskildsen
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands
| | - Matthijs R Panman
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Gergely Tordai
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Mike Koeman
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Klaus Neymeyr
- Institut für Mathematik, Universität Rostock, Rostock, Germany; Leibniz-Institut für Katalyse, Rostock, Germany
| | - Jeroen Jansen
- Institute for Molecules and Materials, Radboud University, Nijmegen, the Netherlands
| | - Age K Smilde
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Sander Woutersen
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, the Netherlands
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13
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Steimers E, Sawall M, Behrens R, Meinhardt D, Simoneau J, Münnemann K, Neymeyr K, von Harbou E. Application of a new method for simultaneous phase and baseline correction of NMR signals (SINC). Magn Reson Chem 2020; 58:260-270. [PMID: 31710133 DOI: 10.1002/mrc.4964] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/17/2019] [Accepted: 10/25/2019] [Indexed: 06/10/2023]
Abstract
Recently, we presented a new approach for simultaneous phase and baseline correction of nuclear magnetic resonance (NMR) signals (SINC) that is based on multiobjective optimization. The algorithm can automatically correct large sets of NMR spectra, which are commonly acquired when reactions and processes are monitored with NMR spectroscopy. The aim of the algorithm is to provide spectra that can be evaluated quantitatively, for example, to calculate the composition of a mixture or the extent of reaction. In this work, the SINC algorithm is tested in three different studies. In an in-house comparison study, spectra of different mixtures were corrected both with the SINC method and manually by different experienced users. The study shows that the results of the different users vary significantly and that their average uncertainty of the composition measurement is larger than the uncertainty obtained when the spectra are corrected with the SINC method. By means of a dilution study, we demonstrate that the SINC method is also applicable for the correction of spectra with low signal-to-noise ratio. Furthermore, a large set of NMR spectra that was acquired to follow a reaction was corrected with the SINC method. Even in this system, where the areas of the peaks and their chemical shifts changed during the course of reaction, the SINC method corrected the spectra robustly. The results show that this method is especially suited to correct large sets of NMR spectra and it is thus an important contribution for the automation of the evaluation of NMR spectra.
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Affiliation(s)
- Ellen Steimers
- Laboratory of Engineering Thermodynamics (LTD), Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Mathias Sawall
- Institute of Mathematics, University of Rostock, Rostock, Germany
| | - Richard Behrens
- Laboratory of Engineering Thermodynamics (LTD), Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Denise Meinhardt
- Institute of Mathematics, University of Rostock, Rostock, Germany
- Leibniz Institut für Katalyse, Rostock, Germany
| | - Joël Simoneau
- Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Kerstin Münnemann
- Laboratory of Engineering Thermodynamics (LTD), Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Klaus Neymeyr
- Institute of Mathematics, University of Rostock, Rostock, Germany
- Leibniz Institut für Katalyse, Rostock, Germany
| | - Erik von Harbou
- Laboratory of Engineering Thermodynamics (LTD), Technische Universität Kaiserslautern, Kaiserslautern, Germany
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14
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Devos O, Schröder H, Sliwa M, Placial JP, Neymeyr K, Métivier R, Ruckebusch C. Photochemical multivariate curve resolution models for the investigation of photochromic systems under continuous irradiation. Anal Chim Acta 2019; 1053:32-42. [PMID: 30712567 DOI: 10.1016/j.aca.2018.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 12/03/2018] [Indexed: 01/23/2023]
Abstract
We propose a multivariate curve resolution approach for the investigation of photochromic systems using UV-Visible spectroscopy. The incorporation of photochemical hard-models as constraints in multivariate curve resolution alternating least squares (MCR-ALS) allows extracting reaction quantum yields in situations where a complete knowledge of the system is not available. We apply this approach to the study of the photochromism of CMTE (cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene) under continuous monochromatic irradiation. The mechanism, involving 3 species and 2 reversible reactions, is written and translated into a kinetic constraint that can be applied to the concentration profiles within ALS. First, ambiguity of the solution obtained for photochemical model(s) is calculated and discussed for single set analysis. Multiset analysis is then proposed combining data obtained under different irradiation wavelengths to provide more reliable results. Finally, the photochemical reactivity of CMTE is widely unraveled, and some description of the mechanism observed under irradiation at 365 nm is given.
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Affiliation(s)
- O Devos
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, 59000, Lille, France.
| | - H Schröder
- Universität Rostock, Institut für Mathematik, Ulmenstrasse 69, 18057, Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059, Rostock, Germany
| | - M Sliwa
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, 59000, Lille, France
| | - J P Placial
- PPSM, ENS Cachan, CNRS, Université Paris-Saclay, Cachan, France
| | - K Neymeyr
- Universität Rostock, Institut für Mathematik, Ulmenstrasse 69, 18057, Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059, Rostock, Germany
| | - R Métivier
- PPSM, ENS Cachan, CNRS, Université Paris-Saclay, Cachan, France
| | - C Ruckebusch
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, 59000, Lille, France.
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15
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Sawall M, von Harbou E, Moog A, Behrens R, Schröder H, Simoneau J, Steimers E, Neymeyr K. Multi-objective optimization for an automated and simultaneous phase and baseline correction of NMR spectral data. J Magn Reson 2018; 289:132-141. [PMID: 29510348 DOI: 10.1016/j.jmr.2018.02.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Spectral data preprocessing is an integral and sometimes inevitable part of chemometric analyses. For Nuclear Magnetic Resonance (NMR) spectra a possible first preprocessing step is a phase correction which is applied to the Fourier transformed free induction decay (FID) signal. This preprocessing step can be followed by a separate baseline correction step. Especially if series of high-resolution spectra are considered, then automated and computationally fast preprocessing routines are desirable. A new method is suggested that applies the phase and the baseline corrections simultaneously in an automated form without manual input, which distinguishes this work from other approaches. The underlying multi-objective optimization or Pareto optimization provides improved results compared to consecutively applied correction steps. The optimization process uses an objective function which applies strong penalty constraints and weaker regularization conditions. The new method includes an approach for the detection of zero baseline regions. The baseline correction uses a modified Whittaker smoother. The functionality of the new method is demonstrated for experimental NMR spectra. The results are verified against gravimetric data. The method is compared to alternative preprocessing tools. Additionally, the simultaneous correction method is compared to a consecutive application of the two correction steps.
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Affiliation(s)
- Mathias Sawall
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany
| | - Erik von Harbou
- Technische Universität Kaiserslautern, Lehrstuhl für Thermodynamik, Erwin-Schrödinger-Straße 44, 67663 Kaiserslautern, Germany
| | - Annekathrin Moog
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany
| | - Richard Behrens
- Technische Universität Kaiserslautern, Lehrstuhl für Thermodynamik, Erwin-Schrödinger-Straße 44, 67663 Kaiserslautern, Germany
| | - Henning Schröder
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany
| | - Joël Simoneau
- Université de Sherbrooke, Department of Chemical & Biotechnological Engineering, 2500 Blvd. de L'Université, Sherbrooke, Canada
| | - Ellen Steimers
- Technische Universität Kaiserslautern, Lehrstuhl für Thermodynamik, Erwin-Schrödinger-Straße 44, 67663 Kaiserslautern, Germany
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, Ulmenstraße 69, 18057 Rostock, Germany; Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Straße 29a, 18059 Rostock, Germany.
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16
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Sawall M, Schmode S, Schröder H, Ludwig R, Neymeyr K. A chemometric study in the area of feasible solution of an acid–base titration of N-methyl-6-oxyquinolone. RSC Adv 2018; 8:9922-9932. [PMID: 35540806 PMCID: PMC9078702 DOI: 10.1039/c7ra13427d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/01/2018] [Indexed: 11/21/2022] Open
Abstract
Multivariate curve resolution methods aim at recovering the underlying chemical components from spectroscopic data on chemical reaction systems. In most cases the spectra and concentration profiles of the pure components cannot be uniquely determined from the given spectral data. Instead continua of possible factors exist. This fact is known as rotational ambiguity. The sets of all possible pure component factors can be represented in the so-called area of feasible solutions (AFS). This paper presents an AFS study of the pure component reconstruction problem for a series of UV/Vis spectra taken from an acid–base titration of N-methyl-6-oxyquinolone. Additional information on the equilibrium concentration profiles for a varying acid concentration is taken from fluorescence measurements. On this basis chemometric duality arguments lead to the construction of a unique final solution. Multivariate curve resolution methods aim at recovering the underlying chemical components from spectroscopic data on chemical reaction systems.![]()
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Affiliation(s)
- Mathias Sawall
- Universität Rostock
- Institut für Mathematik
- 18057 Rostock
- Germany
| | - Stella Schmode
- Universität Rostock
- Institut für Chemie
- 18059 Rostock
- Germany
| | | | - Ralf Ludwig
- Universität Rostock
- Institut für Chemie
- 18059 Rostock
- Germany
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock
| | - Klaus Neymeyr
- Universität Rostock
- Institut für Mathematik
- 18057 Rostock
- Germany
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock
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17
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Sawall M, Neymeyr K. A ray casting method for the computation of the area of feasible solutions for multicomponent systems: Theory, applications and FACPACK-implementation. Anal Chim Acta 2017; 960:40-52. [DOI: 10.1016/j.aca.2016.11.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 10/06/2016] [Accepted: 11/24/2016] [Indexed: 10/20/2022]
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18
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Schröder H, Sawall M, Kubis C, Selent D, Hess D, Franke R, Börner A, Neymeyr K. On the ambiguity of the reaction rate constants in multivariate curve resolution for reversible first-order reaction systems. Anal Chim Acta 2016; 927:21-34. [PMID: 27237834 DOI: 10.1016/j.aca.2016.04.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 02/22/2016] [Accepted: 04/05/2016] [Indexed: 11/28/2022]
Abstract
If for a chemical reaction with a known reaction mechanism the concentration profiles are accessible only for certain species, e.g. only for the main product, then often the reaction rate constants cannot uniquely be determined from the concentration data. This is a well-known fact which includes the so-called slow-fast ambiguity. This work combines the question of unique or non-unique reaction rate constants with factor analytic methods of chemometrics. The idea is to reduce the rotational ambiguity of pure component factorizations by considering only those concentration factors which are possible solutions of the kinetic equations for a properly adapted set of reaction rate constants. The resulting set of reaction rate constants corresponds to those solutions of the rate equations which appear as feasible factors in a pure component factorization. The new analysis of the ambiguity of reaction rate constants extends recent research activities on the Area of Feasible Solutions (AFS). The consistency with a given chemical reaction scheme is shown to be a valuable tool in order to reduce the AFS. The new methods are applied to model and experimental data.
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Affiliation(s)
- Henning Schröder
- Universität Rostock, Institut für Mathematik, Ulmenstrasse 69, 18057 Rostock, Germany
| | - Mathias Sawall
- Universität Rostock, Institut für Mathematik, Ulmenstrasse 69, 18057 Rostock, Germany
| | - Christoph Kubis
- Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
| | - Detlef Selent
- Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
| | - Dieter Hess
- Evonik Performance Materials GmbH, Paul-Baumann Strasse 1, 45772 Marl, Germany
| | - Robert Franke
- Evonik Performance Materials GmbH, Paul-Baumann Strasse 1, 45772 Marl, Germany; Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Armin Börner
- Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
| | - Klaus Neymeyr
- Universität Rostock, Institut für Mathematik, Ulmenstrasse 69, 18057 Rostock, Germany; Leibniz-Institut für Katalyse, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany.
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Golshan A, Abdollahi H, Beyramysoltan S, Maeder M, Neymeyr K, Rajkó R, Sawall M, Tauler R. A review of recent methods for the determination of ranges of feasible solutions resulting from soft modelling analyses of multivariate data. Anal Chim Acta 2016; 911:1-13. [DOI: 10.1016/j.aca.2016.01.011] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/23/2015] [Accepted: 01/04/2016] [Indexed: 11/17/2022]
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Sawall M, Kubis C, Barsch E, Selent D, Börner A, Neymeyr K. Peak group analysis for the extraction of pure component spectra. J IRAN CHEM SOC 2015. [DOI: 10.1007/s13738-015-0727-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Sawall M, Kubis C, Börner A, Selent D, Neymeyr K. A multiresolution approach for the convergence acceleration of multivariate curve resolution methods. Anal Chim Acta 2015; 891:101-12. [DOI: 10.1016/j.aca.2015.07.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/23/2015] [Accepted: 07/27/2015] [Indexed: 12/01/2022]
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22
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Abstract
Chemometric analysis of the IR and UV-Vis absorbance data revealed the pronounced effect of the stability of the associated methanol–water cluster in mixtures of solvents.
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Affiliation(s)
| | | | - M. Shamsipur
- Department of Chemistry
- Razi University
- Kermanshah
- Iran
| | - K. Neymeyr
- Institute of Mathematics
- Rostock University
- Rostock
- Germany
- Leibniz Institute for Catalysis
| | - M. Sawall
- Institute of Mathematics
- Rostock University
- Rostock
- Germany
- Leibniz Institute for Catalysis
| | - A. Mohajeri
- Department of Chemistry
- Shiraz University
- Shiraz
- Iran
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23
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Kubis C, Sawall M, Block A, Neymeyr K, Ludwig R, Börner A, Selent D. An Operando FTIR Spectroscopic and Kinetic Study of Carbon Monoxide Pressure Influence on Rhodium-Catalyzed Olefin Hydroformylation. Chemistry 2014; 20:11921-31. [DOI: 10.1002/chem.201402515] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Indexed: 11/11/2022]
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Sawall M, Kubis C, Franke R, Hess D, Selent D, Börner A, Neymeyr K. How To Apply the Complementarity and Coupling Theorems in MCR Methods: Practical Implementation and Application to the Rhodium-Catalyzed Hydroformylation. ACS Catal 2014. [DOI: 10.1021/cs5003614] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mathias Sawall
- Institut
für Mathematik, Universität Rostock, Ulmenstraße
69, 18057 Rostock, Germany
| | - Christoph Kubis
- Leibniz-Institut
für Katalyse e. V., Universität Rostock, Albert-Einstein-Straße
29a, 18059 Rostock, Germany
| | - Robert Franke
- Evonik Industries AG, Paul-Baumann
Straße 1, 45772 Marl, Germany
- Lehrstuhl
für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Dieter Hess
- Evonik Industries AG, Paul-Baumann
Straße 1, 45772 Marl, Germany
| | - Detlef Selent
- Leibniz-Institut
für Katalyse e. V., Universität Rostock, Albert-Einstein-Straße
29a, 18059 Rostock, Germany
| | - Armin Börner
- Leibniz-Institut
für Katalyse e. V., Universität Rostock, Albert-Einstein-Straße
29a, 18059 Rostock, Germany
| | - Klaus Neymeyr
- Institut
für Mathematik, Universität Rostock, Ulmenstraße
69, 18057 Rostock, Germany
- Leibniz-Institut
für Katalyse e. V., Universität Rostock, Albert-Einstein-Straße
29a, 18059 Rostock, Germany
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25
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Kubis C, Baumann W, Barsch E, Selent D, Sawall M, Ludwig R, Neymeyr K, Hess D, Franke R, Börner A. Investigation into the Equilibrium of Iridium Catalysts for the Hydroformylation of Olefins by Combining In Situ High-Pressure FTIR and NMR Spectroscopy. ACS Catal 2014. [DOI: 10.1021/cs500368z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Christoph Kubis
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
| | - Wolfgang Baumann
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
| | - Enrico Barsch
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
- Institut für Chemie, Universität Rostock, Albert-Einstein Str. 3, D-18059 Rostock, Germany
| | - Detlef Selent
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
| | - Mathias Sawall
- Institut für Mathematik, Universität Rostock, Ulmenstrasse 69, D-18057 Rostock, Germany
| | - Ralf Ludwig
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
- Institut für Chemie, Universität Rostock, Albert-Einstein Str. 3, D-18059 Rostock, Germany
| | - Klaus Neymeyr
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
- Institut für Mathematik, Universität Rostock, Ulmenstrasse 69, D-18057 Rostock, Germany
| | - Dieter Hess
- Evonik Industries AG, Paul-Baumann-Str. 1, D-45772 Marl, Germany
| | - Robert Franke
- Evonik Industries AG, Paul-Baumann-Str. 1, D-45772 Marl, Germany
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Armin Börner
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Str. 29a, D-18059 Rostock, Germany
- Institut für Chemie, Universität Rostock, Albert-Einstein Str. 3, D-18059 Rostock, Germany
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Sawall M, Neymeyr K. On the area of feasible solutions and its reduction by the complementarity theorem. Anal Chim Acta 2014; 828:17-26. [DOI: 10.1016/j.aca.2014.04.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 10/25/2022]
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Kubis C, Selent D, Sawall M, Ludwig R, Neymeyr K, Baumann W, Franke R, Börner A. Exploring Between the Extremes: Conversion-Dependent Kinetics of Phosphite-Modified Hydroformylation Catalysis. Chemistry 2012; 18:8780-94. [DOI: 10.1002/chem.201200603] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Indexed: 11/09/2022]
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28
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Fischer C, Schulz S, Drexler HJ, Selle C, Lotz M, Sawall M, Neymeyr K, Heller D. The Influence of Substituents in Diphosphine Ligands on the Hydrogenation Activity and Selectivity of the Corresponding Rhodium Complexes as Exemplified by ButiPhane. ChemCatChem 2011. [DOI: 10.1002/cctc.201100277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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29
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Kubis C, Ludwig R, Sawall M, Neymeyr K, Börner A, Wiese KD, Hess D, Franke R, Selent D. A Comparative In Situ HP-FTIR Spectroscopic Study of Bi- and Monodentate Phosphite-Modified Hydroformylation. ChemCatChem 2010. [DOI: 10.1002/cctc.200900292] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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30
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Kubis C, Ludwig R, Sawall M, Neymeyr K, Börner A, Wiese KD, Hess D, Franke R, Selent D. Inside Cover: A Comparative In Situ HP-FTIR Spectroscopic Study of Bi- and Monodentate Phosphite-Modified Hydroformylation (ChemCatChem 3/2010). ChemCatChem 2010. [DOI: 10.1002/cctc.201090010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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