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Inhomogeneities in PNIPAM Aqueous Solutions: The Inside View by Spin Probe EPR Spectroscopy. Polymers (Basel) 2021; 13:polym13213829. [PMID: 34771385 PMCID: PMC8588346 DOI: 10.3390/polym13213829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 01/15/2023] Open
Abstract
Coil to globule transition in poly(N-isopropylacrylamide) aqueous solutions was studied using spin probe continuous-wave electronic paramagnetic resonance (CW EPR) spectroscopy with an amphiphilic TEMPO radical as a guest molecule. Using Cu(II) ions as the “quencher” for fast-moving radicals in the liquid phase allowed obtaining the individual spectra of TEMPO radicals in polymer globule and observing inhomogeneities in solutions before globule collapsing. EPR spectra simulations confirm the formation of molten globules at the first step with further collapsing and water molecules coming out of the globule, making it denser.
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2
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Witwicki M, Lewińska A, Ozarowski A. o-Semiquinone radical anion isolated as an amorphous porous solid. Phys Chem Chem Phys 2021; 23:17408-17419. [PMID: 34351330 DOI: 10.1039/d1cp01596f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of metal cations is a commonly applied strategy to create S > 1/2 stable molecular systems containing semiquinone radicals. Persistent mono-semiquinonato complexes of diamagnetic metal ions (S = 1/2) have been hitherto less common and mostly limited to the complexes of heavy metal ions. In this work, a mono-semiquinonato complex of aluminum, derived from 1,2-dihydroxybenzene, is obtained using a surprisingly short and uncomplicated procedure. The isolated product is an amorphous and porous solid that exhibits very good stability under ambient conditions. To characterise its molecular and electronic structure, 9.7, 34 and 406 GHz EPR spectroscopy was used in concert with computational techniques (DFT and DLPNO-CCSD). It was revealed that the radical complex is composed of two chemically equivalent aluminum cations and two catechol-like ligands with the unpaired electron uniformly distributed between the two organic molecules. The good stability and porous structure make this complex applicable in heterogeneous aerobic reactions.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
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3
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Abstract
We review recent work on property decomposition techniques using quantum chemical methods and discuss some topical applications in terms of quantum mechanics-molecular mechanics calculations and the constructing of properties of large molecules and clusters. Starting out from the so-called LoProp decomposition scheme [Gagliardi et al., J. Chem. Phys., 2004, 121, 4994] for extracting atomic and inter-atomic contributions to molecular properties we show how this method can be generalized to localized frequency-dependent polarizabilities, to localized hyperpolarizabilities and to localized dispersion coefficients. Some applications of the generalized decomposition technique are reviewed - calculations of frequency-dependent polarizabilities, Rayleigh scattering of large clusters, and calculations of hyperpolarizabilities of proteins.
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Affiliation(s)
- Hans Ågren
- KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Theoretical Chemistry and Biology, SE-106 91 Stockholm, Sweden.
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4
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Remigio RD, Repisky M, Komorovsky S, Hrobarik P, Frediani L, Ruud K. Four-component relativistic density functional theory with the polarisable continuum model: application to EPR parameters and paramagnetic NMR shifts. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1239846] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Roberto Di Remigio
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Tromsø– The Arctic University of Norway, Tromsø, Norway
| | - Michal Repisky
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Tromsø– The Arctic University of Norway, Tromsø, Norway
| | - Stanislav Komorovsky
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Tromsø– The Arctic University of Norway, Tromsø, Norway
| | - Peter Hrobarik
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Luca Frediani
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Tromsø– The Arctic University of Norway, Tromsø, Norway
| | - Kenneth Ruud
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Tromsø– The Arctic University of Norway, Tromsø, Norway
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5
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Witwicki M. Theoretical Characterisation of Phosphinyl Radicals and Their Magnetic Properties: g Matrix. Chemphyschem 2015; 16:1912-25. [PMID: 25873130 DOI: 10.1002/cphc.201500121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/11/2022]
Abstract
The g matrices (g tensors) of various phosphinyl radicals (R2 P(.) ) were calculated using the DFT and multireference configuration interaction (MRCI) methods. The g matrices were distinctly dependent on the molecular structure of the radical. To thoroughly examine this dependence, the contributions from individual atoms and excited states were calculated. The former revealed the gain from the phosphorus atom to be preeminent unless PO or PS bonds are present in the radical molecule. The contributions owing to excited states arising from electronic transitions between doubly occupied molecular orbitals and the SOMO were clearly positive, as in the case of semiquinone and niroxide radicals. The transitions from the phosphorus lone pair were of paramount importance. Surprisingly, unlike for semiquinones and nitroxides, a significant negative contribution was observed from excitations from the SOMO to unoccupied molecular orbitals. For radicals with PO bonds, this contribution to the g2 component was dominant.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283 (Poland).
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6
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Harczuk I, Vahtras O, Ågren H. Frequency-dependent force fields for QMMM calculations. Phys Chem Chem Phys 2015; 17:7800-12. [DOI: 10.1039/c4cp05411c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The frequency-dependent localized polarizabilities are calculated for the first time using analytical response theory and benchmarked for different water clusters and the tryptophan residue embedded in a protein.
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Affiliation(s)
- Ignat Harczuk
- KTH Royal Institute of Technology
- School of Biotechnology
- Division of Theoretical Chemistry and Biology
- SE-106 91 Stockholm
- Sweden
| | - Olav Vahtras
- KTH Royal Institute of Technology
- School of Biotechnology
- Division of Theoretical Chemistry and Biology
- SE-106 91 Stockholm
- Sweden
| | - Hans Ågren
- KTH Royal Institute of Technology
- School of Biotechnology
- Division of Theoretical Chemistry and Biology
- SE-106 91 Stockholm
- Sweden
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7
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Witwicki M, Jezierska J. DFT insight into o-semiquinone radicals and Ca2+ ion interaction: structure, g tensor, and stability. Theor Chem Acc 2013. [DOI: 10.1007/s00214-013-1383-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Lipparini F, Cappelli C, Barone V. A gauge invariant multiscale approach to magnetic spectroscopies in condensed phase: general three-layer model, computational implementation and pilot applications. J Chem Phys 2013; 138:234108. [PMID: 23802952 PMCID: PMC4630867 DOI: 10.1063/1.4811113] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Analytical equations to calculate second order electric and magnetic properties of a molecular system embedded into a polarizable environment are presented. The treatment is limited to molecules described at the self consistent field level of theory, including Hartree-Fock theory as well as Kohn-Sham density functional theory and is extended to the Gauge-Including Atomic Orbital method. The polarizable embedding is described by means of our already implemented polarizable quantum mechanical/molecular mechanical (MM) methodology, where the polarization in the MM layer is handled by means of the fluctuating charge (FQ) model. A further layer of description, i.e, the polarizable continuum model, can also be included. The FQ(/polarizable continuum model) contributions to the properties are derived, with reference to the calculation of the magnetic susceptibility, the nuclear magnetic resonance shielding tensor, electron spin resonance g-tensors, and hyperfine couplings.
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Affiliation(s)
- Filippo Lipparini
- Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa, Italy
| | - Chiara Cappelli
- Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa, Italy and Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento, 35 I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa, Italy
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9
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Frecus B, Rinkevicius Z, Ågren H. π-Stacking effects on the EPR parameters of a prototypical DNA spin label. Phys Chem Chem Phys 2013; 15:10466-71. [PMID: 23685812 DOI: 10.1039/c3cp51129d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The character and value of spin labels for probing environments like double-stranded DNA depend on the degree of change in the spin Hamiltonian parameters of the spin label induced by the environment. Herein we provide a systematic theoretical investigation of this issue, based on a density functional theory method applied to a spin labeled DNA model system, focusing on the dependence of the EPR properties of the spin label on the π stacking and hydrogen bonding that occur upon incorporating the spin label into the selected base pair inside DNA. It is found that the EPR spin Hamiltonian parameters of the spin label are only negligibly affected by its incorporation into DNA, when compared to its free form. This result gives a theoretical ground for the common empirical assumption regarding the behaviour of spin Hamiltonian parameters made in EPR based measurements of the distance between spin labels incorporated into DNA.
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Affiliation(s)
- Bogdan Frecus
- KTH Royal Institute of Technology, School of Biotechnology, Division of Theoretical Chemistry & Biology, SE-106 91 Stockholm, Sweden.
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10
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Niskanen J, Arul Murugan N, Rinkevicius Z, Vahtras O, Li C, Monti S, Carravetta V, Ågren H. Hybrid density functional–molecular mechanics calculations for core-electron binding energies of glycine in water solution. Phys Chem Chem Phys 2013; 15:244-54. [DOI: 10.1039/c2cp43264a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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Frecus B, Rinkevicius Z, Murugan NA, Vahtras O, Kongsted J, Ågren H. EPR spin Hamiltonian parameters of encapsulated spin-labels: impact of the hydrogen bonding topology. Phys Chem Chem Phys 2013; 15:2427-34. [DOI: 10.1039/c2cp43951d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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12
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Li X, Rinkevicius Z, Kongsted J, Murugan NA, Ågren H. Binding Mechanism and Magnetic Properties of a Multifunctional Spin Label for Targeted EPR Imaging of Amyloid Proteins: Insight from Atomistic Simulations and First-Principles Calculations. J Chem Theory Comput 2012; 8:4766-74. [DOI: 10.1021/ct300606q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Xin Li
- Department of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Zilvinas Rinkevicius
- Department of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
- Swedish e-Science Research Center
(SeRC), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Jacob Kongsted
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - N. Arul Murugan
- Department of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Hans Ågren
- Department of Theoretical Chemistry
and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
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13
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Schwabe T, Sneskov K, Haugaard Olsen JM, Kongsted J, Christiansen O, Hättig C. PERI–CC2: A Polarizable Embedded RI-CC2 Method. J Chem Theory Comput 2012; 8:3274-83. [DOI: 10.1021/ct3003749] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tobias Schwabe
- Center for Bioinformatics and
Institute of Physical Chemistry, University of Hamburg, Bundesstraße
43, D-20146 Hamburg, Germany
| | - Kristian Sneskov
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, DK-8000 Aarhus C, Denmark
- The Lundbeck Foundation Center
for Theoretical Chemistry, Department of Chemistry, Aarhus University,
Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Jógvan Magnus Haugaard Olsen
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230
Odense M, Denmark
| | - Jacob Kongsted
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230
Odense M, Denmark
| | - Ove Christiansen
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, DK-8000 Aarhus C, Denmark
- The Lundbeck Foundation Center
for Theoretical Chemistry, Department of Chemistry, Aarhus University,
Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Christof Hättig
- Lehrstuhl
für Theoretische
Chemie, Ruhr-Universität Bochum, 44801 Bochum, Germany
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14
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Rinkevicius Z, Frecuş B, Murugan NA, Vahtras O, Kongsted J, Ågren H. Encapsulation Influence on EPR Parameters of Spin-Labels: 2,2,6,6-Tetramethyl-4-methoxypiperidine-1-oxyl in Cucurbit[8]uril. J Chem Theory Comput 2011; 8:257-63. [DOI: 10.1021/ct200816z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Zilvinas Rinkevicius
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
- Swedish e-Science Research Center (SeRC), Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Bogdan Frecuş
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - N. Arul Murugan
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Olav Vahtras
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Hans Ågren
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
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15
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Rinkevicius Z, Murugan NA, Kongsted J, Frecuş B, Steindal AH, Ågren H. Density Functional Restricted–Unrestricted/Molecular Mechanics Theory for Hyperfine Coupling Constants of Molecules in Solution. J Chem Theory Comput 2011; 7:3261-71. [DOI: 10.1021/ct2003572] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zilvinas Rinkevicius
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
- Swedish e-Science Research Center (SeRC), Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - N. Arul Murugan
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Jacob Kongsted
- Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Bogdan Frecuş
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Arnfinn Hykkerud Steindal
- Centre of Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
| | - Hans Ågren
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
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