Complex methyl groups dynamics in [(CH3)4P]3Sb2Br9 (PBA) from low to high temperatures by proton spin–lattice relaxation and narrowing of proton NMR spectrum

Latanowicz, L.; Medycki, W.; Jakubas, R.

doi:10.1016/j.ssnmr.2009.09.002

Cited by 9 publications

(15 citation statements)

References 41 publications

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“…Such a reduction was observed for solid MAPBB (9), ADhP (10), and PBA (36). Such a reduction was observed for solid MAPBB (9), ADhP (10), and PBA (36).…”

Section: Proton Second Moment Of Nmr Linementioning

confidence: 64%

“…Such a minimum in T 1 has been observed for solid MAPBB (9), ADhP (10), and PBA (36). At higher temperatures the isotropic tumbling or two-or threefold jumps (the correlation time s x ) of the entire molecule can be dominant.…”

Section: Proton Spin-lattice Relaxation Timementioning

confidence: 70%

“…Analysis of T 1 and M 2 is performed in a wide temperature range from 10 K to melting temperatures on the basis of the data published earlier for CH 3 COOK (potassium acetate) (26), (4-CH 3 PyH)SbCl 4 (4-methylpyridinium tetrachloroantimonate) (35), [(CH 3 ) 4 P] 3 Sb 2 Br 9 (tris(tetramethylphosphonium) nanobromodiantimonate) (36), and (CH 3 ) 3 C 6 D 3 (1,3,5-trimethylbenzene with deuterated ring protons) (37). These solids contain methyl groups differing by the value of tunnelling splitting.…”

Section: Illustrative Examplesmentioning

confidence: 99%

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Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups

Latanowicz

2015

Concepts Magnetic Resonance

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Complex proton dynamics in solids containing methyl groups are studied over a wide temperature range. Temperature dependences of the proton T 1 relaxation time and the second moment of NMR lines are analyzed. General rules describing the temperature dependencies have been formulated from an analysis of the data. The second moments, M 2 , are correlated with those based on T 1 measurements. The C 3 jumps over the barrier cause a minimum in T 1 below the liquid nitrogen temperature in the presence of tunnelling splitting, or a little above 77 K when tunnelling splitting equals zero. The slope of the high-temperature side of this minimum permits evaluation of the activation energy, which can be used to characterize the tunnelling correlation time. The T 1 is temperature independent in the lowest temperature range, indicating that the tunnelling correlation time assumes a constant value. The tunnelling splitting was estimated as the best fit parameter from the T 1 temperature dependence. The high tunnelling splitting is responsible for T 1 values which are high and independent from the Larmor frequency. The tunnelling jumps reduce the rigid lattice second moment at zero Kelvin. The second reduction is caused by over the barrier C 3 jumps of methyl protons. The tunnelling jumps cease above a temperature T tun . The occurrence of the minimum T 1 above liquid nitrogen temperature, as well as the reduction of the second moment M 2 are due to slowest motion of protons, which can be the isotropic motion of molecule. This minimum is well described by the Woessner method of calculating the correlation function of complex motion. V C 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part A 44A: 214-225, 2015.

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“…Such a reduction was observed for solid MAPBB (9), ADhP (10), and PBA (36). Such a reduction was observed for solid MAPBB (9), ADhP (10), and PBA (36).…”

Section: Proton Second Moment Of Nmr Linementioning

confidence: 64%

Section: Proton Spin-lattice Relaxation Timementioning

confidence: 70%

Section: Illustrative Examplesmentioning

confidence: 99%

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Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups

Latanowicz

2015

Concepts Magnetic Resonance

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“…The tunnelling correlation time is independent on temperature therefore, T 1 here is also constant value. Such an effect, a constant value of T 1 has been detected at low temperatures for a number of methyl bearing solids [22,23,[27][28][29][30][31][32][33][34][35][36]. The low temperature flattening of T 1 is not visible for the significant values of 1/T 1(inter) (1/T 1EE contribution) [13,[38][39][40][41][42].…”

Section: Proton Spin-lattice Relaxation Timementioning

confidence: 94%

Complex dynamics of 1.3.5-trimethylbenzene-2.4.6-D3 studied by proton spin–lattice NMR relaxation and second moment of NMR line

Hołderna-Natkaniec

Latanowicz

Medycki

et al. 2015

Journal of Physics and Chemistry of Solids

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“…The tunnel splitting o T of methyl groups in [(CH 3 ) 4 P] þ cation was estimated as of low frequency (a few megahertz) (6). The tunnel splitting o T of methyl groups in [(CH 3 ) 4 P] þ cation was estimated as of low frequency (a few megahertz) (6).…”

Section: Examplementioning

confidence: 99%

Concept of correlation time, autocorrelation functions, and spectral densities of the tunneling jumps through the potential barrier

Latanowicz

2012

Concepts Magnetic Resonance

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The concept of the tunneling correlation time according to Schrö dinger is presented. This tunneling jumps and the over the barrier jumps (Arrhenius type) correlation times are applied to calculate the autocorrelation functions and spectral densities of a complex motion. Complex motion means that the relaxation vector performs more than one motion. Two examples of temperature dependencies of a complex motion in a wide temperature regime are given. One example concerns the complex motion consisting of the fast hindered rotation of the methyl group which participates additionally in a slower isotropic motion. The other example concerns the complex motion consisting of the jumps of the proton-proton vector between the two sites in a double hydrogen bond as well as the jumps between other two equilibrium sites (librations of the whole molecule). The latter motion is assumed as slower than the concerted motion of two protons in a double hydrogen bond. In both examples the tunneling jumps are considered as a component of a complex motion. However, only the tunneling jumps of the faster motion are taken into account. Why the tunneling jumps of the slower motion are neglected is explained. The tunneling spectral density dominates only at low temperatures and contributes to the spectral density of the complex motion at intermediate temperatures up to T tun temperature. The sense of T tun temperature is explained. A comparison is made with the other theories of tunneling correlation time. 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 66-79, 2012.

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Complex methyl groups dynamics in [(CH3)4P]3Sb2Br9 (PBA) from low to high temperatures by proton spin–lattice relaxation and narrowing of proton NMR spectrum

Cited by 9 publications

References 41 publications

Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups

Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups

Complex dynamics of 1.3.5-trimethylbenzene-2.4.6-D3 studied by proton spin–lattice NMR relaxation and second moment of NMR line

Concept of correlation time, autocorrelation functions, and spectral densities of the tunneling jumps through the potential barrier

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Complex methyl groups dynamics in [(CH3)4P]3Sb2Br9 (PBA) from low to high temperatures by proton spin–lattice relaxation and narrowing of proton NMR spectrum

Cited by 9 publications

References 41 publications

Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH3 groups

Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH3 groups

Complex dynamics of 1.3.5-trimethylbenzene-2.4.6-D3 studied by proton spin–lattice NMR relaxation and second moment of NMR line

Concept of correlation time, autocorrelation functions, and spectral densities of the tunneling jumps through the potential barrier

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Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups

Spin‐lattice NMR relaxation and second moment of NMR line in solids containing CH₃ groups