2.5.4. Resonance Energy (RN)

The resonance energy (RN) of the CT complexes was estimated according to Equation (6) presented by Briegleb and Czekalla [21].

$$
\varepsilon\_{\text{max}} = 7.7 \times 10^{-4} / [\text{hv}\_{\text{CT}} / \text{R}\_{\text{N}}] - 3.5 \,\text{J} \tag{6}
$$

## 2.5.5. Dissociation Energy (W) (eV)

Further evidence of the nature of CT interactions of the synthesized CT complexes was calculated according to Equation (7).

$$\mathbf{W} = \mathbf{I}\mathbf{P} - \mathbf{E}^{\mathbf{A}} - \mathbf{E}\_{\mathbf{C}\mathbf{T}} \tag{7}$$

2.5.6. Gibbs Free Energy Change (ΔG◦)

Finally, the nature of the interaction of CT complexes was examined using Gibbs free energy calculation as shown in ΔG◦ Equation (8).

$$
\Delta \mathbf{G}^{\diamond} = -\mathbf{R} \mathbf{T} \ln \mathbf{K}\_{\mathbf{C}\mathbf{T}} \tag{8}
$$

## *2.6. DFT Calculations*

Single-point density functional theory (DFT) calculations were performed using the long-range corrected hybrid functional ωB97XD in conjunction with the 6-311++G(2d,p) basis set. All the DFT calculations were performed using Gaussian 16, Revision C.01 [22] in the gas phase first, and then the optimized structures were further calculated in the acetonitrile solvent system using the polarized continuum model (PCM). A vibrational analysis was carried out for each optimized molecule to ensure that they were in a vibrational energy minimum and had no imaginary frequencies (Supplementary Materials).
