Table 3.
DFT IEs and UV/Vis data of 1 and acids 4
| Entry | Compound | Ionisation energy [eV][a] | λmax [nm] | λcutoff[b] [nm] | ε [L mol−1 cm−1] |
|---|---|---|---|---|---|
| 1 | 1 | – | 269 | 351 | 652 |
| 2 | 4 a | 6.28 | 269 | 309 | 971 |
| 3 | 4 b | 6.00 | 281 | 294 | 1225 |
| 4 | 4 c | 6.04 | 272 | 303 | 1229 |
| 5 | 4 d | 5.69, 5.67[c] | 286 | 321 | 2529 |
| 6 | 4 e | 6.01 | 278 | 291 | 1708 |
| 7 | 4 f | 5.80 | 273 | 292 | 2119 |
| 8 | 4 g | 6.01 | 246 | 286 | 482 |
| 9 | 4 h | 5.17, 5.35[c] | 273 | 296 | 1099 |
| 10 | 4 i | 5.99 | 246 | 302 | 6106 |
| 11 | 4 j | 5.53, 5.53[c] | 255 | 320 | 7307 |
| 12 | 4 k | 5.53, 5.52[c] | 296 | 323 | 1295 |
| 13 | 4 l | 5.49 | 294 | 321 | 2120 |
[a] DFT method: UB3LYP/aug-cc-pvtz/CPCM-acetonitrile; IE values corrected to 298 K. [b] Cutoff taken to be the point at which absorbance ≤0.5 A.U. [c] cisoid- and transoid- conformers, respectively (see text).