Molecular dynamics and local molecular conformation in solid materials studied by nuclear magnetic resonance

Abstract

After the huge development occurred during the last 30 years, including the proposition of methods such as magic-angle spinning, multiple-resonance experiments (cross-polarization, high-power decoupling, etc.), multiple-pulses techniques, multiple quantum experiments, and multidimensional spectroscopy, pulsed Solid-State NMR became one of the most important experimental tools for studying physical and chemical properties of new materials in the solid-state. In this article we will review some of the NMR methods employed for studying an important class of solid materials: organic materials, particularly polymers and derivatives, which allow the application of a large number of different techniques for understanding their molecular dynamics and local conformation.

Correlation Between Molecular Conformation, Packing, and Dynamics in Oligofluorenes: A Theoretical/Experimental Study

“…The distinct behavior of 5F6 can be understood by considering the tendency of this oligomer to adopt specific chain arrangements. In the more stable theoretical configuration of 5F6, the aliphatic side chains of different molecules can organize themselves into a more compact packing structure, 40 which explains the higher tendency to form a crystalline phase. It is important to mention that the use of different solvents and preparation procedures might induce the formation of other ordered phases, as was already described regarding the same type of oligomers documented in the literature.…”

NMR Study of Mangífera Índica Starch Applied as Food Human

“…This section gives a brief introduction about the exchange methods employed in this work. Detailed descriptions of the methods described below are found in references [20][21][22][23][24][25]. 2D Exchange NMR.…”

Structure and dynamics of poly(9,9-dioctylfluoren-2,7->i<co>/i<-benzothiadiazole) (F8BT) and correlations with its electrical properties

“…The most commonly used 1 H decoupling method consists of a continuous irradiation in resonance with hydrogen, while the carbon signal is measured. Such irradiation will artificially rotate the hydrogen's magnetization in such a way that the dipolar field in the carbon site is averaged out 68,69 . To efficiently suppress the C-H dipolar coupling the intensity of the applied irradiation field (B 1 ) must satisfy the relation:…”

“…The combination of the techniques mentioned before, i.e., decoupling, MAS and CP, is used in order to converge to the well-known Cross-Polarization Magic The DIPSHIFT methodology correlates two spin interactions already discussed in this work, the heteronuclear dipolar interaction ( 1 H -13 C) and the 13 C chemical-shift, and provides useful information concerning internuclear distance, torsion angles of molecular dynamics. [64][65][66][67][68] Technically, the NMR spectrum acquired in this experiment is obtained under 1 H decoupling, CP and MAS. Therefore, it is possible to measure high resolution 13 C spectra, composed by narrow lines arising from carbons in different chemical groups.…”

“…The CODEX technique is a NMR methodology which belongs to a set of experiments known as Exchange [64][65][66][67][68] . Essentially, the Exchange methods measure changes in the molecular orientation by probing the orientation of the chemicalshift tensor, which occurs in the time scale ranging from seconds to milliseconds.…”