Molecular dynamics in a blue phase liquid crystal: a 1H fast field-cycling NMR relaxometry study

Gradišek, Anton; Apih, T.; Domenici, Valentina; Novotná, Vladimı́ra; Sebastião, Pedro J.

doi:10.1039/c3sm51625c

Cited by 15 publications

(33 citation statements)

References 40 publications

(62 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An example of two-exponential and single-exponential fittings of the magnetization recorded at high and low fields for the sample L1 in the isotropic phase reported Figure S1 (Supplementary Materials). Similar phenomena have been observed before, for example in HZL 7/* [56] and 10BBL [57] liquid crystals, where multi-exponential functions gave better fitting of the magnetization than a single-exponential function. In such cases [56,57], the different components were attributed to the relaxation of methyl, methylene, and aromatic protons in the LC molecule.…”

Section: H Nmr Relaxometrysupporting

confidence: 87%

“…Another important NMR technique is represented by 1 H NMR relaxometry, based on the experimental measurement of 1 H spin-lattice relaxation times, T 1 , at different 1 H Larmor frequencies, typically from few KHz to several tens of MHz [49][50][51][52]. The analyses of the frequency-dependence of 1 H NMR T 1 can be done invoking different dynamic contributions by means of suitable theoretical models [51][52][53][54][55][56][57][58][59].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

et al. 2019

Self Cite

View full text Add to dashboard Cite

In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled 9/2 RS/RS, and a bimesogenic liquid crystal labelled L1, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of 1H NMR diffusometry and 1H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the 1H spin-lattice relaxation time (T1) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of 1H T1 at different temperatures gives information about the main motional processes active in the isotropic mesophases.

show abstract

Section: H Nmr Relaxometrysupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…35 The details of the experimental techniques used with each equipment can be found in the literature. 24,34,[36][37][38] Viscosity measurements…”

Section: H-nmr Assaysmentioning

confidence: 99%

¹H NMR Relaxation Study of a Magnetic Ionic Liquid as a Potential Contrast Agent

et al. 2015

View full text Add to dashboard Cite

A proton nuclear magnetic relaxation dispersion (1)H NMRD study of the molecular dynamics in mixtures of magnetic ionic liquid [P66614][FeCl4] with [P66614][Cl] ionic liquid and mixtures of [P66614][FeCl4] with dimethyl sulfoxide (DMSO) is presented. The proton spin-lattice relaxation rate, R1, was measured in the frequency range of 8 kHz-300 MHz. The viscosity of the binary mixtures was measured as a function of an applied magnetic field, B, in the range of 0-2 T. In the case of DMSO/[P66614][FeCl4] the viscosity was found to be independent from the magnetic field, while in the case of the [P66614][Cl]/[P66614][FeCl4] system viscosity decreased with the increase of the magnetic field strength. The spin-lattice relaxation results were analyzed for all systems taking into account the relaxation mechanisms associated with the molecular motions with correlation times in a range between 10(-11) and 10(-7)s, usually observed by NMRD, and the paramagnetic relaxation contributions associated with the presence of the magnetic ions in the systems. In the case of the DMSO/[P66614][FeCl4] system the R1 dispersion shows the relaxation enhancement due to the presence of the magnetic ions, similar to that reported for contrast agents. For the [P66614][Cl]/[P66614][FeCl4] system, the R1 dispersion presents a much larger paramagnetic relaxation contribution, in comparison with that observed for the DMSO/[P66614][FeCl4] mixtures but different from that reported for other magnetic ionic liquid system. In the [P66614][Cl]/[P66614][FeCl4] system the relaxation enhancement associated with the paramagnetic ions is clearly not proportional to the concentration of magnetic ions, in contrast with what is observed for the DMSO/[P66614][FeCl4] system.

show abstract

“…Some representative examples of the problems addressed by researchers are fluid dynamics at the solid interface, transport in porous media (filtration, imbibition, and conduction), [21] role of physical chemistry at the pore surface (proton exchange and wettability), [22,23] phase transitions in confinement, hydration of proteins, biological tissues and membranes, [24][25][26][27][28] dynamics of water at the protein surface, [29][30][31][32][33][34][35] dynamics of polymers [36][37][38][39][40][41] and liquid crystals, [12,[42][43][44][45] and the study of MRI contrast agents and differential diagnosis.…”

Section: Discussionmentioning

confidence: 99%

New applications and perspectives of fast field cycling NMR relaxometry

Steele

Korb

Ferrante

et al. 2015

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

The field cycling NMR relaxometry method (also known as fast field cycling (FFC) when instruments employing fast electrical switching of the magnetic field are used) allows determination of the spin-lattice relaxation time (T1 ) continuously over five decades of Larmor frequency. The method can be exploited to observe the T1 frequency dependence of protons, as well as any other NMR-sensitive nuclei, such as (2) H, (13) C, (31) P, and (19) F in a wide range of substances and materials. The information obtained is directly correlated with the physical/chemical properties of the compound and can be represented as a 'nuclear magnetic resonance dispersion' curve. We present some recent academic and industrial applications showing the relevance of exploiting FFC NMR relaxometry in complex materials to study the molecular dynamics or, simply, for fingerprinting or quality control purposes. The basic nuclear magnetic resonance dispersion features are outlined in representative examples of magnetic resonance imaging (MRI) contrast agents, porous media, proteins, and food stuffs. We will focus on the new directions and perspectives for the FFC technique. For instance, the introduction of the latest Wide Bore FFC NMR relaxometers allows probing, for the first time, of the dynamics of confined surface water contained in the macro-pores of carbonate rock cores. We also evidence the use of the latest field cycling technology with a new cryogen-free variable-field electromagnet, which enhances the range of available frequencies in the 2D T1 -T2 correlation spectrum for separating oil and water in crude oil. Copyright © 2015 John Wiley & Sons, Ltd.

show abstract

Molecular dynamics in a blue phase liquid crystal: a 1H fast field-cycling NMR relaxometry study

Cited by 15 publications

References 40 publications

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

¹H NMR Relaxation Study of a Magnetic Ionic Liquid as a Potential Contrast Agent

New applications and perspectives of fast field cycling NMR relaxometry

Contact Info

Product

Resources

About

Molecular dynamics in a blue phase liquid crystal: a 1H fast field-cycling NMR relaxometry study

Cited by 15 publications

References 40 publications

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

1H NMR Relaxation Study of a Magnetic Ionic Liquid as a Potential Contrast Agent

New applications and perspectives of fast field cycling NMR relaxometry

Contact Info

Product

Resources

About

¹H NMR Relaxation Study of a Magnetic Ionic Liquid as a Potential Contrast Agent