Table 8.
Photophysical properties of α-pyrones 6.
| Entry | Compound | R1 | R2 | λmax,abs [nm]a (ε [L·mol−1·cm−1]) | λmax,em [nm]b (Φf)c | Stokes shift Δν̃ [cm−1] |
| 1 | 6a | Ph | Ph | 258 (15300), 311 (12800), 381 (18000) | – | – |
| 2 | 6b | p-MeOC6H4 | Ph | 254 (10300), 271 (11500), 312 (9600), 404 (21900) | – | – |
| 3 | 6c | p-Me2NC6H4 | Ph | 294 (18800), 482 (47300) | 567 (0.99) | 3100 |
| 4 | 6d | Ph | p-MeOC6H4 | 258 (19700), 358 (30400) | – | – |
| 5 | 6e | Ph | p-Me2NC6H4 | 255 (25600), 289 (23300), 375 (39600), 453 (40600) | 634 (0.01) | 6300 |
| 6 | 6f | p-MeOC6H4 | p-MeOC6H4 | 254 (15000), 364 (25600), 400 (25100) | – | – |
| 7 | 6g | p-F3CC6H4 | p-Me2NC6H4 | 251 (16200), 309 (13900), 372 (20200), 465 (21600) | 673 (<0.01) | 6600 |
aRecorded in dichloromethane, T = 293 K, c(6) = 10−6 M; brecorded in dichloromethane, T = 293 K, c(6) = 10−7 M (λexc = 465 nm); cfluorescence quantum yields were determined relative to DCM (Φf = 0.435) as a standard in ethanol [58].