Medium range interactions evidences in compounds with aliphatic lateral chain: 1-pentanoic acid, 1-pentanol and pentylammonium nitrate as test cases

In this study we have explored by means of polarizable molecular dynamics simulations and small-angle X-ray diffraction, a subset of liquids belonging to the following three different classes of compounds: pentyl ammonium nitrate, 1-pentanol and 1-pentanoic acid. The presence of a low-Q peak in the X-ray spectra of the liquids provides evidence that a long alkyl chain is connected to the polar moiety and it is sufficient to establish nanodomain segregation in the liquid. From the calculations, we have obtained the theoretical scattering patterns that reproduce very nicely the experimental spectra in the low-Q ranges. From detailed analyses of the radial distribution functions, we infer that the medium-range ordering in these liquids stems from the joined effects of both strong and weak interactions.