SAMPL4, a blind challenge for computational solvation free energies: the compounds considered

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Thermodynamics

Background:

• Solvation energy calculations are crucial for understanding chemical behavior in solution.
• Previous SAMPL challenges highlighted the need for accurate solvation energy data.
• Experimental determination of solvation energies can be complex and resource-intensive.

Purpose of the Study:

• To provide an updated set of solvation energies for blind and supplementary compounds for the SAMPL challenge.
• To detail the experimental origins and calculation methods for these solvation energies.
• To investigate and correct for factors affecting vapor pressure measurements and extrapolations.

Main Methods:

• Calculation of solvation energies from experimental data (1 M gas to 1 M aqueous).
• Correction of vapor pressures from subcooled liquid to sublimation, incorporating fusion entropy (ΔSfusion) and heat capacity (ΔCp) effects.
• Utilizing boiling point data as a substitute for vapor pressure studies, with outlier rejection criteria.

Main Results:

• A comprehensive dataset of solvation energies for 23 blind and 30 supplementary compounds is presented.
• The impact of estimated ΔSfusion and ΔCp values on solvation energy calculations was quantified.
• Reliability criteria for using boiling point data in solvation energy calculations were established.

Conclusions:

• The refined methods enhance the accuracy of solvation energy predictions.
• Careful consideration of experimental conditions and thermodynamic corrections is vital for reliable solvation energy data.
• This work contributes valuable data and methodologies for future computational chemistry challenges.