Miscibility and diffusivity of water in organic acids: Molecular dynamics simulations

Water/organic liquid interface properties with amine, carboxyl, thiol, and methyl terminal groups as seen from MD simulations

“…It should be noted that the same trend persists when taking into account hydrogen bonds in the case of n-alkyl carboxylic acid/water systems. 7 Indeed, our calculations have shown that the number of n HB of H-bonds between water molecules and the carboxyl terminal group are equal to 10839 for acetic, 3034 for butyric and 728 for hexanoic acids, respectively. At the same time, the value of the normal component of the diffusion coefficient 10 9 D z ðT ¼ 300 KÞ for H 2 O molecules at the water/acetic, butyric and hexanoic acid interfaces also gradually decreases and is equal to 2.74, 2.63, and 2.17, respectively.…”

“…In molecular dynamics (MD) simulations the liquid/liquid system is visible with full atomistic resolution, and hence simulations can provide such a detailed insight into structure of interfacial area, which cannot be achieved by any experiments. [3][4][5][6][7] MD simulations, on the other hand, treat a suitable model instead of the real system of interest itself, and relevance of this model can only be proven by reproducing existing experimental data on these systems. In this respect, experimental and MD simulations studies can well complement each other in the investigation of interfacial properties of both immiscible and miscible organic liquids.…”

“…Recently, the MD simulations of miscibility and diffusivity of water molecules in carboxylic acids have been carried out. 7 It was found that the aqueous domain confined between the two domains of acetic acid is completely mixed with acetic acid molecules, while in the case of hexanoic acid, the process of mixing water molecules is much slower than in the case of acetic acid. Since, for instance, the vast majority of acetic acid molecules do not dissociate when a sample is dissolved in water, the miscibility has to do with the interactions between acetic acid molecules and water molecules.…”

Functional-Group Effect of Ligand Molecules on the Aggregation of Gold Nanoparticles: A Molecular Dynamics Simulation Study

“…The slope of these curves corresponds to the diffusion coefficient ( D ) according to the Einstein relation. 63 When Figure 8 a,b is compared, it can be said that in the last 30 ns period, the MSD curves of NPs for system I with the polar COOH terminal group ( Figure 8 b) are almost parallel to each other because the NPs aggregate and their trajectories are nearly the same. After aggregation, the slopes of the curves become smaller because the mobility of the gold NPs with a polar terminal group is low.…”

“…To get information about the mobility of functionalized gold NPs in a toluene medium during the first 30 ns (before aggregation/dispersion) and the last 30 ns (after aggregation/dispersion) of the total simulation time, the mean squared displacement of the COM of each NP is calculated and the MSDs for systems I and IV are given as an example in Figures and , respectively. The slope of these curves corresponds to the diffusion coefficient ( D ) according to the Einstein relation . When Figure a,b is compared, it can be said that in the last 30 ns period, the MSD curves of NPs for system I with the polar COOH terminal group (Figure b) are almost parallel to each other because the NPs aggregate and their trajectories are nearly the same.…”