Amides electrical structural effects

These calculations are of special interest because Purcell and coworkers have been interested in the structure-activity relationships of this series of compounds for several years and have compared several approaches to structure-activity relationships with the same compounds. Earlier they (27, 28) reported on detailed studies of the effect of partition coefficients (benzene-water), electric moments, and electronic structures on the relative activity of the congeners. Purcell (28) used Huckel molecular orbital theory to calculate the net charges on all the atoms of each compound. The only apparent success was the apparent correlation of the net charge at the amide nitrogen atom with activity. This was later shown to be caused by the statistically significant correlation between the 7T value and the net charge on the nitrogen atom (29). 

Bruma et al. prepared several poly(amide imide sulfone)s [140] and investigated the thermal and dielectric properties of the polymers. The fluorinated polymer as shown in Scheme 3.10 had the lowest Tg, 279 °C, which resulted from the combined effects of meta-structures with the highest amount of flexible bridges, -SO2- and -0-, per repeat unit of the macromolecule. The dielectric constants of polymer films were in the range 3.49, close to the dielectric constant (3.2) of Kapton. This shows that introduction of hexafluoroisopropylidene units into the main chain does not significantly affect the electrical properties probably both amide and sulfone groups, which are polar, were also present in the macromolecule. 

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