solvophobicity parameter, \(Sp\)

https://doi.org/10.1351/goldbook.S05763
A solvent parameter defined by: \[Sp = 1 - \frac{M}{M\left(\text{hexadecane}\right)}\] derived from the Gibbs energy of transfer (Δ t G°) of a series of solutes from water to numerous aqueous-organic mixtures and to pure solvents: \[\Delta _{\text{t}}G^{\,\unicode{x26ac}}\left(\text{to solvent}\right) = M\ R_{\text{T}}+D\] where R T is a solute parameter, and M and D characterize the solvent. The M values are used to define a solvent solvophobic effect so that Sp values are scaled from unity (water) to zero (hexadecane).
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1165 (https://doi.org/10.1351/pac199466051077)