*3.4. Formation Constant*

Upon plotting the values [A]/A against l/[Do], a straight line was obtained (Figure 4). The molar absorptivity and formation constant in acetonitrile were found to be 0.6 × 10<sup>3</sup> L mol−<sup>1</sup> cm−<sup>1</sup> and 1 × 103 L mol<sup>−</sup>1cm<sup>−</sup><sup>1</sup> for the PA-CHA complex and 14 × 10<sup>3</sup> and 0.1 × 103 L mol−<sup>1</sup> for the DDQ complex, respectively. Those values indicate the stability of the CT complexes. The formation constant values show that the stability of the PA-ChA complex is higher than that of the PA-DDQ complex.

## *3.5. Spectroscopic Physical Parameters*
