UV/vis data, PSDs and thermal relaxation half-life of the Z-isomer in different solvents.
| Compound | E isomer π–π*, λmax/nm | Z isomer π–π*, λmax/nm | Z isomer n–π*, λmax/nm | Max. achievable ratios | t 1/2 (Z → E) [min] | ||
|---|---|---|---|---|---|---|---|
| PSS Za [%] (λirr) | PSS Eb [%] (λirr) | DMSOc | Bufferd | ||||
| 3a | 380 | 348 | 462 | 82 ± 3 (400) | 95 (530) | 397 | 415 |
| 3b | 397 | 333 | 455 | 92 ± 3 (400) | 100 (530) | 139 | 4.4 |
| 3c | 387 | 346 | nd | 82 ± 3 (400) | 94 (530) | 124 | 96 |
| 3d | 386 | 346 | 447 | 85 ± 3 (400) | 96 (530) | 449 | 164 |
| 3pz | 381 | nd | 432 | 91 ± 3 (385) | 95 (530) | ∼2.3de | 409f |
| 8a | 383 | 349 | 463 | 84 ± 3 (400) | 90 (530) | 350 | 89 |
| 8b | 400 | 338 | 469 | 92 ± 3 (400) | 100 (617) | 22 | 1.8 |
| 8d | 391 | 351 | 463 | 83 ± 3 (400) | >99 (590) | 246 | 38 |
| 8e | 408 | 382 | nd | 49 ± 4 (400) | 100 (617) | 27 | 14 |
| 8pz | 381 | nd | 440 | 91 ± 3 (400) | 87 (530) | 697e | 321 |
| 13aH | 415 | 388 | nd | 66 ± 4 (400) | 100 (590) | 6.1 | 0.2 |
| 13a | 408 | 379 | nd | 69 ± 4 (400) | >99 (590) | 94 | 12 |
| 13b | 420 | 342 | 476 | 80 ± 4 (400) | 100 (617) | 25 | 1.5 |
| 13c | 413 | 387 | nd | 63 ± 4 (400) | >99 (590) | 76 | 10 |
| 13d | 416 | 388 | nd | 61 ± 4 (475) | >99 (590) | 59 | 7.8f |
| 13e | 441 | nd | nd | 29 ± 4 (475) | 98 (617) | 44 | 6.5f |
| 13f | 419 | 389 | nd | 41 ± 4 (475) | >99 (590) | 99 | 7.5 |
| 13pz | 404 | 370 | 451 | 80 ± 4 (400) | 100 (590) | 490e | 41 |
| 18a | 415 | 380 | nd | 69 ± 4 (475) | >99 (617) | 33 | 4.2 |
| 18b | 430 | 341 | 479 | 80 ± 4 (475) | 100 (617) | 7.0 | 0.8 |
| 18d | 429 | 390 | 457 | 66 ± 4 (475) | >99 (617) | 21 | 2.3 |
| 18pz | 366 | 339 | 437 | 80 ± 4 (400) | >99 (590) | 190 | 12 |
| 23a | 377 | 308 | 461 | 82 ± 3 (400) | 89 (530) | 742 | 213 |
| 23b | 402 | 334 | 481 | 87 ± 3 (400) | 100 (617) | 97 | 8.2 |
| 23c | 381 | 307 | 467 | 77 ± 4 (400) | 94 (530) | 424 | 187g |
| 23d | 385 | 307 | 465 | 84 ± 3 (400) | 99 (590) | 189 | 61 |
| 26a | 381 | 346 | 454 | 78 ± 4 (400) | 97 (590) | 115 | 65 |
| 26b | 409 | 349 | nd | 84 ± 4 (400) | 100 (617) | 24 | 1.2 |
a
Z-isomer PSDs were determined as previously described (c.f. ESI).19
b
E-isomer PSDs were obtained via LC/MS measurements in MeOH; λirr = irradiation wavelength to achieve max. PSS [nm].
c
Measured at 22 °C.
d
Measured at 37 °C, buffer = TRIS-buffer (pH = 7.4, containing 25% DMSO for solubility).
e
Half-life was extrapolated.
f
1 : 1 DMSO/TRIS-buffer (pH = 7.4).
g
3 : 1 DMSO/TRIS-buffer (pH = 7.4); nd = not determinable; d = days.