Intrinsic rotation

The first term in eq. [21] is the contribution of the intrinsic rotational strengths if oscillators a and/or b are themselves chiral. The second term is the coupled oscillator contribution due to the intrinsic moments and the third term is the coupled oscillator contribution due to the geometric arrangement of the two electric dipole oscillators. The latter two contributions give rise to a conservative bisignate couplet in the observed spectrum, if the coupled modes are sufficiently separated in frequency such that the positive and negative contributions do not cancel. 

Magnetic resonance imaging ultimately depends on the observation that nuclear particles, including protons, neutrons and electrons, have an intrinsic rotation or spin, creating an electromagnetic field. The magnetic fields... 

The PCM/DFT model failed to predict the intrinsic rotation (i.e. the specific rotation extrapolated to infinite dilution) of (R)-3-methylcyclopentanone dissolved in carbon tetrachloride, methanol and acetonitrile [68], This molecule has been investigated because it exists in both an equatorial and an axial form, allowing researchers to investigate the interplay of solvent and conformational effects. The conformer populations used in the Boltzmann averaging were derived from IR absorption and VCD spectra. The deviation of the calculated optical rotation from experiment was found actually to be larger when IEF-PCM was used to account for direct solvent effects (and geometry relaxation) on the optical rotation than when the gas-phase values were used. 

An alternative approach to improve the catalyst design was taken by Maikov and Kocovslcy [80], who employed acyclic N-methyl amino acids in the core of the catalyst structure, as illustrated by catalysts 85 and 86 (Table 7.8). (For experimental details see Chapter 14.21.3). Intrinsic rotational flexibility of the bond linking the stereogenic center with the formamide nitrogen allowed the molecule to adopt the most favorable conformation in the transition state. As a result,... 

The preceding conclusions may be suitably checked upon comparison with PDMS. We send the interested reader to ref. 15 for the choice of the parameters. Unlike the case of PS, a molten polymer sample was also considered, in which case the hydrodynamic interaction was assumed to vanish [i.e., v(q) = 1] because of the hydrodynamic screening exerted by the polymer chains. In view of the apparently low energy barriers to the rotation around SUO chain bonds, we assumed the internal viscosity to be absent, that is. To = O Incidentally, we remark the difference from the case of polystyrene where, in addition to the intrinsic rotation barrier around C-C bonds adjoining tetrahedral-coordinated atoms ( 3 kcal/mol), the side phenyl rings contribute significantly to the rotational hindrance. In Figure 13 the characteristic times ti/2 [13/4 for the melts [115]] are plotted versus Q. 

Electrons have an intrinsic rotation called spin, which may point in only two possible directions, specified by a quantum number m Two electrons in the same orbital with... 

In the "vertical" pin-on-disc configuration, the motion is complex and results in an intrinsic rotation of the contact area. This intrinsic rotation appears to be responsible for the special wear behaviour of PTFE and linear polythenes which are observed to be sensitive to the orientation of their molecular chains in the contact region. 

V mon is simply the sum of the intrinsic rotational strengths of the individual molecules, with the contribution of each subunit weighted by the square of the corresponding coefficient in Pb - This term, sometimes called the one-electron contribution, is independent of how the two molecules are arranged with respect to each other in the dimer, assuming that the intermolecular interactions do not affect the magnetic and electronic transition dipoles of the individual molecules. However, it could reflect perturbations of or by the electrostatic environment in the dimer. 

Polavarapu PL, Petrovic AG, Wang F. Intrinsic rotation and molecular structure. Chirality 2003 15(S1) S143-S 149. 

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