Table 2. Summary of free energies of formation of radical ion pairs, ΔGIP, calculated as described in the text as well as rate constants for charge separation, kCS, and recombination, kCR.
| ΔGIP, eV
|
kCS, s-1
|
||||
|---|---|---|---|---|---|
| n | PTZ+·-FLn-PDI-· | PTZ-FLn+·-PDI-· | FS-TA | TRF | kCR, s-1 |
| 1 | 1.88 | 2.56 | 1.3 × 1010 | 1.3 × 1010 | 4.3 × 107 |
| 2 | 2.00 | 2.36 | 1.6 × 109 | 1.6 × 109 | 3.4 × 106 |
| 3 | 2.06 | 2.22 | 1.0 × 109 | 6.3 × 108 | 1.8 × 107 |
| 4 | 2.10 | 2.37 | 4.2 × 108 | 3.3 × 108 | 5.9 × 107 |
Values of free energies are accurate to approximately ±0.1 eV. All values of kCS were measured by femtosecond transient absorption (FS-TA) and time-resolved fluorescence (TRF). All values of kCR were measured by nanosecond transient absorption, with 1–3 measured from PDI-· decay at 720 nm and 4 measured from 3*PDI formation at 455 nm.