Table 1.
Summary of GPx-like catalytic activities of selenides in water and in MeOH along with the second-order rate constants for oxidation and the HOMO (highest occupied molecular orbital) energy levels.
| Selenides | ν0 (μM·min−1) a | t50 (min) b | kox (M−1·s−1) c | HOMO in Water (eV) d | Substituents |
|---|---|---|---|---|---|
| No catalyst | 32.2 (±3.2) | >300 >300 (4~10 equiv. HCl) |
‒ | ‒ | ‒ |
| 5 | 61.3 (±3.4) | 24 | f | ‒6.39 | NH3+ax |
| 6 | 52.6 (±2.1) | 17 5 (+ 4 equiv. HCl) 3 (+10 equiv. HCl) |
0.23 (± 0.02) | ‒6.56 (ax) | NH3+ax |
| MASred (7) e | 59.8 (±1.1) | 14 | 0.47 (± 0.05) | ‒6.44 | NH3+ax |
| DASred (8) e | 47.2 (±4.3) | 7 | 0.14 (±0.02) | ‒5.32 | NH3+ax, NH3+ax |
| DHSred (9) e | 54.2 (±4.0) | 40 | 0.57 (± 0.03) | ‒6.16 | OHax, OHax |
a Initial velocities (ν0) of H2O2 reduction in phosphate buffer at pH 7.4 and 25 °C; b Reaction times for 50% conversion of DTTred to DTTox in CD3OD estimated from Figure 3B; c The second-order rate constants for the reaction of selenide + H2O2 → selenoxide + H2O in water; d Calculated at B3LYP/6-31+G(d,p) in water using the polarizable continuum model (PCM); e Data were quoted from Reference [29]; f Not determined. MASred: monoamino cyclic selenide; DASred: diamino cyclic selenide; DHSred: dihydroxy cyclic selenide