TY - JOUR
T1 - Thermodynamic stability of hydrogen-bonded systems in polar and nonpolar environments
AU - Pašalić, Hasan
AU - Aquino, Adélia J.A.
AU - Tunega, Daniel
AU - Haberhauer, Georg
AU - Gerzabek, Martin H.
AU - Georg, Herbert C.
AU - Moraes, Tatiane F.
AU - Coutinho, Kaline
AU - Canuto, Sylvio
AU - Lischka, Hans
PY - 2010/7/30
Y1 - 2010/7/30
N2 - The thermodynamic properties of a selected set of benchmark hydrogen-bonded systems (acetic acid dimer and the complexes of acetic acid with acetamide and methanol) was studied with the goal of obtaining detailed information on solvent effects on the hydrogen-bonded interactions using water, chloroform, and n-heptane as representatives for a wide range in the dielectric constant. Solvent effects were investigated using both explicit and implicit solvation models. For the explicit description of the solvent, molecular dynamics and Monte Carlo simulations in the isothermal-isobaric (NpT) ensemble combined with the free energy perturbation technique were performed, to determine solvation free energies. Within the implicit solvation approach, the polarizable continuum model and the conductor-like screening model were applied. Combination of gas phase results with the results obtained from the different solvation models through an appropriate thermodynamic cycle allows estimation of complexation free energies, enthalpies, and the respective entropic contributions in solution. Owing to the strong solvation effects of water the cyclic acetic acid dimer is not stable in aqueous solution. In less polar solvents the double hydrogen bond structure of the acetic acid dimer remains stable. This finding is in agreement with previous theoretical and experimental results. A similar trend as for the acetic acid dimer is also observed for the acetamide complex. The methanol complex was found to be tbermodynamically unstable in gas phase as well as in any of the three solvents.
AB - The thermodynamic properties of a selected set of benchmark hydrogen-bonded systems (acetic acid dimer and the complexes of acetic acid with acetamide and methanol) was studied with the goal of obtaining detailed information on solvent effects on the hydrogen-bonded interactions using water, chloroform, and n-heptane as representatives for a wide range in the dielectric constant. Solvent effects were investigated using both explicit and implicit solvation models. For the explicit description of the solvent, molecular dynamics and Monte Carlo simulations in the isothermal-isobaric (NpT) ensemble combined with the free energy perturbation technique were performed, to determine solvation free energies. Within the implicit solvation approach, the polarizable continuum model and the conductor-like screening model were applied. Combination of gas phase results with the results obtained from the different solvation models through an appropriate thermodynamic cycle allows estimation of complexation free energies, enthalpies, and the respective entropic contributions in solution. Owing to the strong solvation effects of water the cyclic acetic acid dimer is not stable in aqueous solution. In less polar solvents the double hydrogen bond structure of the acetic acid dimer remains stable. This finding is in agreement with previous theoretical and experimental results. A similar trend as for the acetic acid dimer is also observed for the acetamide complex. The methanol complex was found to be tbermodynamically unstable in gas phase as well as in any of the three solvents.
KW - Complexation in solution
KW - Explicit and implicit solvation models
KW - Hydrogen-bonded systems
KW - Molecular dynamics and monte carlo simulations
KW - Thermodynamic properties
UR - http://www.scopus.com/inward/record.url?scp=84962439242&partnerID=8YFLogxK
U2 - 10.10021/jcc.21491
DO - 10.10021/jcc.21491
M3 - Article
C2 - 20127744
AN - SCOPUS:84962439242
SN - 0192-8651
VL - 31
SP - 2046
EP - 2055
JO - Journal of Computational Chemistry
JF - Journal of Computational Chemistry
IS - 10
ER -