Extending to multi-substituted systems (Figure ), we assume additivity of Hammett parameters We find a strong correlation (R 2 = 0.86) between the difference in single-excitation character (%R 1 (T 1 ) -%R 1 (S 1 )) and ∆E ST for monosubstituted systems (Figure , left). Similar to our CT analysis, electron-donating groups like -N(CH 3 ) 2 and -NH 2 produce the largest differences in excitation character between states. Examining absolute %R 1 values reveals that T 1 shows greater variability in response to substitution, while S 1 remains relatively stable in its wavefunction character across different substituents.