Inter- and Intramolecular Relaxation in Molecular Liquids by Field Cycling 1H NMR Relaxometry

Meier, R.; Kruk, Danuta; Bourdick, Axel; Schneider, E.; Rössler, E. A.

doi:10.1007/s00723-012-0410-1

Cited by 52 publications

(97 citation statements)

References 31 publications

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“…The results are also compared with the relative diffusion coefficients of pure propylene glycol. 39 The values obtained for the solution of 4-oxo-TEMPO-h 16 -14 N from regime III are in very good agreement with those for pure solvent. This implies that in the investigated temperature range the diffusion coefficients of the paramagnetic molecule are close to the diffusion coefficients of the solvent molecule; this applies also to glycerol solutions (Fig.…”

Section: Analysis and Discussionsupporting

confidence: 62%

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Kruk

Korpała

Kubica

et al. 2013

The Journal of Chemical Physics

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For nitroxide radicals in solution one can identify three frequency regimes in which (1)H spin-lattice relaxation rate of solvent molecules depend linearly on square root of the (1)H resonance frequency. Combining a recently developed theory of nuclear (proton) spin-lattice relaxation in solutions of nitroxide radicals [D. Kruk et al., J. Chem. Phys. 137, 044512 (2012)] with properties of the spectral density function associated with translational dynamics, relationships between the corresponding linear changes of the relaxation rate (for (14)N spin probes) and relative translational diffusion coefficient of the solvent and solute molecules have been derived (in analogy to (15)N spin probes [E. Belorizky et al., J. Phys. Chem. A 102, 3674 (1998)]). This method allows a simple and straightforward determination of diffusion coefficients in spin-labeled systems, by means of (1)H nuclear magnetic resonance (NMR) relaxometry. The approach has thoroughly been tested by applying to a large set of experimental data-(1)H spin-lattice relaxation dispersion results for solutions of different viscosity (decalin, glycerol, propylene glycol) of (14)N and (15)N spin probes. The experiments have been performed versus temperature (to cover a broad range of translational diffusion coefficients) using field cycling spectrometer which covers three decades in (1)H resonance frequency, 10 kHz-20 MHz. The limitations of NMR relaxometry caused by the time scale of the translational dynamics as well as electron spin relaxation have been discussed. It has been shown that for spin-labeled systems NMR relaxometry gives access to considerably faster diffusion processes than for diamagnetic systems.

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Section: Analysis and Discussionsupporting

confidence: 62%

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Kruk

Korpała

Kubica

et al. 2013

The Journal of Chemical Physics

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“…18,19 On the basis of the universal dispersion law (eq 1), one can rescale R 1 (ω) reaching a common low-frequency behavior…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Iso-Frictional Mass Dependence of Diffusion of Polymer Melts Revealed by¹H NMR Relaxometry

et al. 2013

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We extract the translational diffusion coefficient D(T,M) from field cycling (FC) 1 H NMR relaxometry which provides the relaxation dispersion of poly(dimethylsiloxane), 1,4-poly(butadiene), poly(styrene), 1,4-poly(isoprene), and poly(propylene glycol) with various molecular masses M. Oligomers with very low M, nonentangled (M < M e ), and entangled (M > M e ) polymers are included. The low-frequency 1 H NMR relaxation dispersion is dominated by translational dynamics and allows extracting D via benefiting from an universal dispersion power-law characteristic of free diffusion. In order to correct for the additional mass dependence of the monomeric friction coefficient observed at low M and controlled by the M dependence of the glass transition, the segmental correlation time τ s (T,M) is taken from previous analyses of the FC susceptibility master curves. Consequently, we present the temperature independent, iso-frictional quantity Dτ s ∝ F(M), which reveals the M-dependence of the pure collective polymer dynamics. While at the lowest M the quantity Dτ s displays a trend to become M independent typical of simple liquids, it crosses over to a behavior characteristic of Rouse dynamics. In most systems, however, this crossover manifests itself in a rather narrow M interval as entanglement dynamics takes over at M > M e . Thus, pure Rouse behavior is difficult to identify, yet the approach allows one to decide when a molecule becomes a polymer, in terms of the (smallest) Rouse unit.

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“…Actually, the experimentally observed ratio may be larger, reaching 60 3. 10, 11, 15 The timescale separation allows the total relaxation dispersion ${R_1 \left( \omega \right)}$ to be decomposed into contributions associated with the rotational and translational dynamics (see Section 3.1).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…23 It has been shown that the intermolecular spectral density can be approximated by a sum of the purely translational term ${J_{{\rm{trans}}} \left( \omega \right)}$ and a rotational contribution [Eq. (9)]:11, 15 …”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Thus, in the present Minireview, attention is drawn to the role of the intermolecular dipolar relaxation, which only recently has been studied systematically by FC 1 H NMR relaxometry 6–11. It is demonstrated that, by benefiting from the dominating contribution of the intermolecular relaxation at low frequencies, one can determine, in addition to rotational time constants, translation diffusion coefficients of liquids and polymer melts 11–15. Moreover, in the case of subdiffusive motion in polymer systems, even the mean square displacement as a function of time can be revealed and compared to polymer theories 7.…”

Section: Introductionmentioning

confidence: 97%

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Reactivity of Fluoro‐Substituted Bis(thiocarbonyl) Donors with Diiodine: An XRD, FT–Raman, and DFT Investigation

Mancini

Aragoni

Bingham

et al. 2013

Chemistry An Asian Journal

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The reactions of 1,3,8,10-tetrakis(4'-fluorophenyl)-4,5,6,7-tetrathiocino[1,2-b:3,4-b']diimidazolyl-2,9-dithione (4) and molecular diiodine afforded spoke adducts with stoichiometries 4·I2 and 4·3I2 , isolated in the compound 4·3I2·xCH2Cl2·(1-x)I2 (x=0.70), and characterized by single-crystal XRD and FT-Raman spectroscopy. The nature of the reaction products was investigated under the prism of theoretical calculations carried out at the DFT level. The structural data, FT-Raman spectroscopy, and quantum mechanical calculations agree in indicating that the introduction of fluorophenyl substituents results in a lowering of the Lewis basicity of this class of bis(thiocarbonyl) donors compared with alkyl-substituted tetrathiocino donors and fluorine allows for extended interactions that are responsible for solid-state crystal packing.

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Inter- and Intramolecular Relaxation in Molecular Liquids by Field Cycling 1H NMR Relaxometry

Cited by 52 publications

References 31 publications

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Iso-Frictional Mass Dependence of Diffusion of Polymer Melts Revealed by¹H NMR Relaxometry

Reactivity of Fluoro‐Substituted Bis(thiocarbonyl) Donors with Diiodine: An XRD, FT–Raman, and DFT Investigation

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Inter- and Intramolecular Relaxation in Molecular Liquids by Field Cycling 1H NMR Relaxometry

Cited by 52 publications

References 31 publications

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

Iso-Frictional Mass Dependence of Diffusion of Polymer Melts Revealed by1H NMR Relaxometry

Reactivity of Fluoro‐Substituted Bis(thiocarbonyl) Donors with Diiodine: An XRD, FT–Raman, and DFT Investigation

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Iso-Frictional Mass Dependence of Diffusion of Polymer Melts Revealed by¹H NMR Relaxometry