Molecular size parameters

Examination of 3-indolyl compounds for relationships between antioxidation potential (using in vitro LP assays) and electronic, polar, and steric parameters, including bond dissociation energies, bond lengths, dipole moments, electronic charge densities, and molecular size parameters showed that antioxidant efficacy of 3-indolyl compounds was most strongly predicted... 

M. Meireles, A. Beissieres, I. Rogissart, P. Aimar and V. Sanchez, An appropriate molecular size parameter for porous membrane calibration. /. Membr. Sci, 103 (1/2) (1995) 105. 

Experience has shown that the RED number combined with a solvent molecular size parameter, such as the molar volume, frequently provides all the technical information required to evaluate solvent quality. The original Hildebrand theory predicted that larger solvent molecules are inherently poorer solvents than smaller counterparts with the same cohesion energy parameter. Molecular size... 

The SAFT equation of state typically contains five pure compound parameters, which are estimated from both vapor pressure and liquid density data. These are the molecular size parameter m, the segment size parameter v, the segment energy parameter u°lk, and the two association parameters the association energy e /k and the association volume. ... 

It can be seen that the relaxation time becomes independent of temperature and depends only on the viscosity of the fluid and molecular size parameters. Hildebrand adapted a theory of viscosity to self-diffusivity ... 

Similar to the work of Wolbach and Sandler for the molecular size parameters, Sheldon and co-workers" " derived values for m and a by mapping the molecular dimensions calculated from Hartree-Fock calculations onto a sphero-cylinder the remaining parameters were then determined by comparison to the usual vapour pressure and saturated liquid density data. Promising... 

The essence of the application of these equations to real fluids consists of three parts first the replacement of the hard-sphere results for the pure gas viscosity and the interaction viscosity by the values for the real fluid system second, the evaluation of a pseudo-radial distribution function for each binary interaction to replace the hard-sphere equivalent at contact and, finally, the selection of a molecular size parameter for each binary interaction to account for the mean free-path shortening in the dense gas. 

However, as there are various measure of the size of a macromolecule (for instance, the radius of gyration and the hydrodynamic radius), a fundamental problem in the theory of SEC has been the choice of a proper molecular size parameter by which molecules of different kinds are separated. Experimentally, Benoit and co-workers found an excellent correlation between elution volume and a dynamically based molecular size, the hydrodynamic volume, for several different chain architecture and chemical compositions. The observed correlation based on the hydrodynamic volume became accepted as the basis of universal SEC calibration. 

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