Table 1.
No. | Substituted group | Hammett parameter
|
Absorption
peak
|
Midpoint potential
|
Reduction by
l-lactate
|
Reduction by
l-mandelate
|
Oxidation by
O2
|
Reaction with sulfite
|
|||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
σpara | σortho | Σσ | Free, nm | Bound, nm | Free, mV | Bound, mV | kred, s−1 | Kd, mM | KIE | kred, s−1 | Kd, mM | KIE | kox, s−1⋅M−1 | kon, s−1⋅M−1 | koff, s−1 | ||
1 | 8-CN- | +0.66 | −0.06 | +0.60 | 454 | 464 | −50 | +47 | 714 | 0.55 | 1.7 | 12.2 | 0.38 | 4.3 | 2.76 × 104 | 5.1 × 105 | 5.0 × 10−4 |
2 | 8-Cl- | +0.23 | −0.06 | +0.17 | 442 | 454 | −152 | −65 | 600 | 0.42 | 0.270 | 0.35 | 5.01 × 105 | 4.3 × 105 | 8.7 × 10−3 | ||
3 | 8-H- | +0.00 | −0.06 | −0.06 | 448 | 460 | −180 | −110 | 726 | 0.51 | 0.051 | 0.28 | 8.01 × 105 | 4.0 × 105 | 0.020 | ||
4 | 8-H-,6-CH3- | +0.00 | −0.12 | −0.12 | 452 | 464 | −198 | −142 | 263 | 1.20 | 0.045 | 1.00 | 1.56 × 104 | — | — | ||
5 | 8-CH3S- | +0.00 | −0.06 | −0.06 | 476 | 492 | −204 | −151 | 220 | 62 | 0.019 | 11 | 9.22 × 105 | 1,020 | 0.3 | ||
6 | 8-CH3- | −0.17 | −0.06 | −0.23 | 448 | 457 | −207 | −128 | 320 | 1.00 | 4.6 | 0.038 | 0.64 | 3.8 | 1.84 × 106 | 1.5 × 105 | 0.076 |
7 | 8-(CH3)2N- | −0.83 | −0.06 | −0.89 | 505 | 509 | −246 | −220 | 2.17 | 245 | — | — | 1.98 × 106 | 17.6 | 0.93 | ||
8 | 6-O−- | −0.17 | −0.25* | −0.42* | 428 | 426 | −255 | −270 | 0.038 | 97 | — | — | 1.96 × 104 | — | — | ||
9 | 6-NH2- | −0.17 | −0.34 | −0.51 | 428 | 444 | −278 | −217 | 8.71 | 4.06 | — | — | 1.20 × 105 | — | — | ||
10 | 8-S−- | −0.53* | −0.06 | −0.59* | 520 | 600 | −290 | −224 | 0.026 | 0.12 | — | — | 1.26 × 106 | 45 | — | ||
11 | 8-NH2- | −0.66 | −0.06 | −0.72 | 480 | 482 | −310 | −255 | 1.76 | 1.63 | >3 | — | — | 3.58 × 106 | 1,230 | 2.2 | |
12 | 8-O−- | −0.81 | −0.06 | −0.87 | 475 | 485 | −331 | −318 | <10−3 | — | — | — | 1.62 × 106 | 2 | 0.36 |
KIE, the kinetic isotope effect.
*Average value between neutral and anionic form.