A Multiple-Quantum1H NMR Study of Conformational Biasing of Biphenyl in a Nematic Liquid Crystal

Torsion sensitivity in NMR of aligned molecules: study on various substituted biphenyls

“…The latter precision is still much higher, compared to the ones in the literature. [9,13,28,29] Data for BP and DCBP in various media were taken from Refs. [9,13,28] and [29] respectively.…”

“…[21,22] The development of methods for extracting the conformational distribution function from intertorsion dipolar couplings in LXNMR made it possible to study BP with higher precision in solution, but slightly different values were obtained for the preferred twist angle depending on the theoretical approach and unexpectedly close values obtained in different types of aligning media. [9,13] Values of 37.4 ± 0.2…”

Multiple Quantum and High-Resolution NMR, Molecular Structure, and Order Parameters of Partially Oriented ortho and meta Dimethyl-, Dichloro-, and Chloromethylbenzenes Codissolved in Nematic Liquid Crystals

“…However, estimates of spectral parameters can be obtained from analysis of MQ NMR spectra. MQ spectra tend to be easier than high-resolution spectra to analyze since there are comparatively fewer lines (3,4,(22)(23)(24)(25)(26). However, broad peaks, poor resolution, and a lack of correlation between the intensities of calculated and experimental frequencies can make analysis of the MQ spectrum somewhat difficult, but not as difficult as analysis of the high-resolution spectrum.…”

“…a version of the least-squares routine modified to include the subroutine VICO (42,43), which corrects for the nonnegligible effects of normal mode molecular vibrations on D ij using Eq. [4]. Mean square amplitudes ͗⌬␦ 2 ͘ were calculated using the program MSAV (44) from normal mode vibrational analysis using force constants from Refs.…”

Obtaining the structure and bond rotational potential of a substituted ethane by NMR spectroscopy of solutions in nematic liquid-crystalline solvents

“…6,7 For molecules with just a single bond rotational motion it should be possible to test models for the bond rotation potential, and a classic case is a molecule such as biphenyl. 8,9 In this case there are a sufficient number of interproton dipolar couplings obtained from an analysis of the proton spectrum of a sample dissolved in a liquid-crystalline solvent to establish the relative positions of the protons within each ring, the separation of the two rings, and test models for the interring rotation potential. There have been a number of such studies on similar molecules to biphenyl, but the same is not the case for simple, substituted ethanes XCH 2 CH 2 Y.…”