Table 2. Photo-physical characteristics of the Pd(ii) complexes.
| Complex | UV/Vis absorption λabs (nm) (ε (104 dm3 mol–1 cm–1)) a | Emission |
||
| λ max (nm) (τobs (μs)) a | Φ em | k r; knr f (s–1) | ||
| Pd-B-1 | 259 (3.39), 282 (2.83), 298 (sh, 2.21), 317 (1.73), 339 (0.98), 387 (sh, 0.17) | 466, 495 (106) | 0.47 b ; 0.64 c | 4.43 × 103; 5.00 × 103 |
| Pd-B-2 | 249 (2.61), 294 (1.12), 323 (1.21), 338 (sh, 1.02), 387 (sh, 0.16) | 466, 497 (48) | 0.39 b ; 0.54 c | 8.13 × 103; 1.27 × 104 |
| Pd-B-3 | 257 (3.49), 281 (sh, 2.73), 298 (sh, 2.01), 318 (1.61), 335 (sh, 0.97), 380 (sh, 0.16) | 456, 483 (69) | 0.20 b ; 0.09 c | 2.90 × 103; 1.16 × 104 |
| Pd-B-4 | 271 (3.57), 280 (sh, 3.38), 297 (sh, 2.27), 3.16 (1.70), 356 (1.33), 372 (sh, 1.12), 404 (sh, 0.18) | 599 (44) | 0.07 d ; 0.04 c | 1.59 × 103; 2.11 × 104 |
| Pd-G-1 | 253 (4.75), 284 (sh, 2.10), 323 (sh, 1.00), 338 (1.48), 357 (sh, 1.00), 403 (br, 0.71) | 517 (55.4) | 0.22 d ; 0.27 e | 3.97 × 103; 1.41 × 104 |
| Pd-N-1 | 254 (3.48), 301 (sh, 1.16), 329 (sh, 0.88), 347 (1.10), 400 (br, 0.57), 422 (sh, 0.52) | 515 (272) | 0.18 d ; 0.01 c | 6.62 × 102; 3.01 × 103 |
aDetermined in degassed CH2Cl2 (2 × 10–5 mol dm–3).
bEmission quantum yield was measured by using the optical dilute method with BPEA (9,10-bis(phenylethynyl)anthracene) in degassed benzene as the reference (Φem = 0.85).
cEmission quantum yield was measured in PMMA thin film with a dopant concentration of 10 wt%.
dEmission quantum yield was measured by the optical dilution method with [Ru(bpy)3](PF6)2 (bpy = 2,2′-bipyridine) in degassed CH3CN as the reference (Φem = 0.062).
eEmission quantum yield was measured in mCP thin film with a doping concentration of 10 wt%.
fRadiative decay rate constant estimated from the equation kr = Φem/τ; nonradiative decay rate constant estimated from the equation knr = (1 – Φem)/τ.