Table 3.
Quenching rate constant (kq) and numerical value of Hammett parameters (σ) for the indicated photosensitizer/aryl diazonium combinations.
| Diazonium (σ) | [Ru(bpy)3]2+a | [Os(bpy)3]2+a | [Ir(ppy)3]a | [Ir((dFCF3)ppy)2(dtb)]+ a | [Ir(ppy)2(dtb)]+ a |
|---|---|---|---|---|---|
| NMe2 (−0.83) | 1.08 | 1.67 | 8.97 | 1.43 | 2.25 |
| NEt2 (−0.72) | 1.34 | 2.25 | 11.8 | 2.86 | 3.11 |
| MeO (−0.27) | 1.51 | 2.59 | 13.2 | 1.84 | 3.52 |
| C6H11 (−0.15) | 2.37 | 4.83 | 12.1 | 2.49 | 4.32 |
| Et (−0.15) | 2.37 | 4.12 | 16.1 | 2.52 | 3.93 |
| COO− (0) | 2.43 | 3.67 | 7.24 | 2.30 | 3.42 |
| Br (0.23) | 5.33 | 7.11 | 17.9 | 4.74 | 7.06 |
| COOEt (0.45) | 5.52 | 6.08 | 12.5 | 4.24 | 5.92 |
| CF3 (0.54) | 6.71 | 6.17 | 17.2 | 4.78 | 6.53 |
| NO2 (0.78) | 10.3 | 25.1 | 20.2 | 9.07 | 10.9 |
| X4-A | 4.37 | 10.8 | 20.5 | 5.59 | 10.3 |
| X4-B | 4.37 | 7.30 | 11.5 | 3.18 | 8.68 |
| X4-C | 5.70 | 10.2 | 16.7 | 5.12 | 10.0 |
a
kq (×109 M−1s−1). Experiments were carried out at room temperature in argon purged acetonitrile containing 0.1M TBABF4 electrolyte.