These terms can be interpreted as the energy change due to electron transfer and electrostatic energy due to Coulombic force, respectively. In this context, the regression coefficients 𝛼 M-Host , 𝛽 M-Host , and 𝛾 M-Host can be considered as the HSAB quantitative index for the host, the size effect quantitative index for the host, and the correction constant unique to each host, respectively.