Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2007
Publication Date: February 6, 2008
Citation: Schnupf, U., Willett, J.L., Bosma, W.B., Momany, F.A. 2008. DFT solvation studies of carbohydrates: implicit and explicit solvation. American Chemical Society Abstracts. xx. Technical Abstract: Solvents play a role in carbohydrate structure. Therefore, it is important to include solvation effects in calculations to allow a more realistic comparison with experimental data. A possible way to include solvation effects is to use implicit solvation models such as COSMO and PCM. Another avenue is the use of explicit hydration. Both methods, implicit and explicit hydration, pose interesting questions. In the current investigation, explicit stepwise hydration, in conjunction with the COSMO and PCM solvation model, was used to achieve a more accurate description of the properties and behavior associated with carbohydrates. Geometry optimization, at the B3LYP/6-311++G** level of theory with COSMO and PCM, were carried out on selected low energy structures of explicitly hydrated glucose and glucose epimers. Zero point energy, enthalpy, entropy, and relative Gibbs Free energies are reported at the harmonic level of theory. A comparison of the structural differences and differences in alpha/beta-anomeric ratios between the vacuum, explicitly hydrated, implicitly hydrated (COSMO and PCM) and explicitly hydrated in conjunction with COSMO/PCM structures will be given. In addition, results of DFT dynamics simulations on mono-saccharides, including the COSMO solvation term, will be presented. Further, a comparison will be given between the implicit solvation model COSMO and PCM.