A neutron scattering and modelling study of aqueous solutions of tetramethylammonium and tetrapropylammonium bromide

作者：Nilsson Emelie J; Alfredsson Viveka; Bowron Daniel T; Edler Karen J^*

来源：Physical Chemistry Chemical Physics, 2016, 18(16): 11193-11201.

DOI：10.1039/c6cp01389a

We have investigated the properties in water of two tetraalkylammonium bromides (tetramethylammonium, TMA(+), and tetrapropylammonium, TPA(+)), at 0.4 M, using neutron scattering coupled with empirical potential structure refinement to arrive at an atomistic description. Having both a polar and an apolar moiety, it is of interest to determine the strength of each moiety as a function of the alkyl chain length. TMA(+) and TPA(+), having different impact as structure directors in zeolite synthesis, were chosen for this study. Water arranges tetrahedrally around TMA(+) and in an almost featureless manner around TPA(+). TMA(+) and TPA(+) show an apolar hydration with TPA(+) being slightly more apolar. TPA(+) has a tendency to form small clusters of 2-4 molecules and to fold into a compact configuration. Both molecules correlate similarly with the bromide ion but do not dissociate completely at this concentration.

• 出版日期2016-4-28