Intramolecular orientational

Brown s reactivity index, Z-value 73), is also the one in which the frontier term solely controls the intramolecular orientation. 

The intramolecular orientations of the transition dipoles for the St and S2 bands of ethidium were determined from polarized fluorescence studies of... 

A more serious factor that has direct regard to initial steps of mesophase formation in polymer solutions has to be assessed. That is the interaction between the molecules of LC polymer and of the solvent. The conformation of the macromolecule appears to be sensitive to the thermodynamic quality of the solvent, and this has a very pronounced effect on the mode of intramolecular structure formation. For instance, the folding of the chain in a bad solvent leads to a sharp rise in intramolecular orientational ordering of the side branches. This is manifest as an increase of optical... 

To gain better understanding of and to control molecular assembly processes, one needs chemical imaging techniques that can follow interactions at a broad range of length and time scales. During assembly, it would be advantageous to record inter- and intramolecular orientations and distances at picosecond to second... 

Appendix. Intramolecular Orientational Ordering in the Isotropic Phase. . 95... 

To find the anisotropy of the whole molecule in molecular coordinates h, the value of cos d should be averaged over all chain elements and all its conformations corresponding to a given value of h. To solve this problem Kuhn and Griin ) have considered the statistics of the intramolecular orientational distribution of segments with respect to h in a freely jointed chain and have shown that for the most probable distribution the value of cos d averaged over all chain segments can be expressed as a unique function of the h/L ratio... 

Intramolecular orientational order in polymer molecules was investigated by a comprehensive study of the conformation of these molecules in the unassociated state... 

Table 2 gives the experimental data on the degree of Intramolecular orientational axial order S for a series... 

Table 2. Intramolecular Orientational-Axial Order Degree S for Some Mesogenic Polymers. 

It may be assumed that the decisive part in the appearance of lyotropic mesomorphism in a concentrated polymer solution is played by the parameter A which determines the degree of its intramolecular orientational axial order, Experimental data show that in contrast to low molecular weight liquid crystals, in this case, the mesomorphism is determined by the length of the part that is of rodlike shape rather than by the chain length as a whole. 

NMR relaxation and small-angle X-ray scattering indicated that the intramolecular orientation is only slightly affected by the presence of other chains in the glassy amorphous state and that axial correlation is of the order of 1 nm or less. 

The study of the molecular organization of lyotropic and some thermotropic comb-shaped polymers was of primary importance in understanding the mechanism of formation of intramolecular orientational order [9] these concepts subsequently served as the basis for notions on ordering of liquid-crystal polymers on the molecular level. 

Devanathan, S. and Ramamurthy, V., Intramolecular orientation at the micellar interface control of Norrish type I and type II reactivity of benzoin alkyl ethers via conformational effects, /. Phys. Org. Chem., 1,91,1988. 

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