I would like to know What is the best method for predicting the water solubility (and in other solvents) of a compound given its molecular structure at different pHs. What I know now is based on the seminal paper from Eisenberg et al.;
Eisenberg, D. & McLachlan, A. D. Solvation energy in protein folding and binding. Nature 319, 199–203 (1986).
where partition coefficient can be estimated depending on each atom type and its exposed surface to the solvent (SASA). This seems to work well for many substances, but I have the problem that I need to know the solubility dependence of some substances against pH, and I the only thing I found now as Chemaxon tools, but their results are not very accurate. It seems that the best option might be quantum mechanical calculations and tools such as COSMO-RS. At the moment we can not pay its license.
So in summary, I wonder what approaches do you suggest for calculating solubility of small chemical compounds depending on pH. Any method/software/server would be fine for us.