Contribution of Proton NMR Relaxation to the Investigation of Molecular Dynamics and Molecular Organisation in Liquid Crystalline Phases

Deuterium NMR spectroscopy is a very powerful technique for studying partially or totally ordered systems, such as liquid crystals (LCs) and polymers. LCs represent a branch of the most general class of soft materials, with peculiar physical and chemical properties which attracted scientific attention for their potentiality for technological applications. From a chemical point of view, there are three aspects in which 2H NMR could provide significant insights: (i) the conformational and structural properties; (ii) the molecular dynamics and mobility; and (iii) the orientational order and aggregation/distribution of molecules in the different liquid-crystalline phases. In this work, some of the recent developments in this field are discussed, focusing on two main topics: (1) the molecular dynamics of the smectic liquid-crystalline phases formed by rod-like molecules and (2) the unusual orientational and dynamic properties of the new liquid-crystalline mesophases formed by banana-shaped molecules (BLCs).

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Molecular Dynamics in Side-Group Polymers with and without Liquid Crystalline Phases from 2H NMR

Berichte der Bunsengesellschaft für physikalische Chemie ◽

10.1002/bbpc.19930971019 ◽

1993 ◽

Vol 97 (10) ◽

pp. 1306-1311 ◽

Cited By ~ 3

Author(s):

J. Leisen ◽

A. Ohlemacher ◽

C. Boeffel ◽

H. W. Spiess

Keyword(s):

Molecular Dynamics ◽

Liquid Crystalline ◽

2H Nmr ◽

Side Group ◽

Crystalline Phases ◽

Liquid Crystalline Phases

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Orientation of Laurdan in Phospholipid Bilayers Influences Its Fluorescence: Quantum Mechanics and Classical Molecular Dynamics Study

Molecules ◽

10.3390/molecules23071707 ◽

2018 ◽

Vol 23 (7) ◽

pp. 1707 ◽

Cited By ~ 10

Author(s):

Mirza Wasif Baig ◽

Marek Pederzoli ◽

Piotr Jurkiewicz ◽

Lukasz Cwiklik ◽

Jiri Pittner

Keyword(s):

Molecular Dynamics ◽

Lipid Bilayers ◽

Lipid Membranes ◽

Liquid Crystalline ◽

Lipid Membrane ◽

Emission Spectra ◽

Crystalline Phases ◽

Classical Molecular Dynamics ◽

Liquid Crystalline Phases ◽

Lipid Environment

Fluidity of lipid membranes is known to play an important role in the functioning of living organisms. The fluorescent probe Laurdan embedded in a lipid membrane is typically used to assess the fluidity state of lipid bilayers by utilizing the sensitivity of Laurdan emission to the properties of its lipid environment. In particular, Laurdan fluorescence is sensitive to gel vs liquid–crystalline phases of lipids, which is demonstrated in different emission of the dye in these two phases. Still, the exact mechanism of the environment effects on Laurdan emission is not understood. Herein, we utilize dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC) lipid bilayers, which at room temperature represent gel and liquid–crystalline phases, respectively. We simulate absorption and emission spectra of Laurdan in both DOPC and DPPC bilayers with quantum chemical and classical molecular dynamics methods. We demonstrate that Laurdan is incorporated in heterogeneous fashion in both DOPC and DPPC bilayers, and that its fluorescence depends on the details of this embedding.

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