Table 1.
Structural information and physical properties of mixed-stack complexes
| Donor (D)–acceptor (A) | 2O–F4 | 2O–F2 | 2S–F4 | 2S–F2 |
|---|---|---|---|---|
| Experimental data | ||||
| ΔEREDOX ( = E1/21(D) − E1/21 (A)) (V)a | −0.04 | 0.20 | 0.15 | 0.39 |
| D–A interplanar distance (Å)b | 3.361 | 3.329 | 3.406 | 3.398 |
| δ from bond length analyses in A | 0.79(2) | 0.71(4) | 0.69(2) | 0.46(3) |
| σ at 300 K (σrt; S cm−1) | 4.9 × 10−4 | 1.4 × 10−2 | 0.10 | 6.9 × 10−3 |
| hνCT (eV) | 0.83 | 0.73 | 0.64 | 0.50 |
| Ea for high temperature region (eV)c | 0.113(1) (290–315 K) | 0.178(1) (259–337 K) | 0.200(1) (288–340 K) | 0.112(1) (288–312 K) |
| Ea for low temperature region (eV)c | 0.215(2) (238–258 K) | 0.225(4) (219–231 K) | 0.277(3) (228–273 K) | 0.0902(17) (221–244 K) |
| Calculated data | ||||
| Eg (eV)d | 0.05 | <0.01e | <0.01 | 0.02e |
| W (eV)d | 0.86 | 0.89e | 0.88 | 0.89e |
| tDA (eV)f | 0.203 | 0.209e | 0.208 | 0.206e |
| Ueff (D) (eV)f | 2.31 | 2.28e | 1.89 | 1.89e |
| Ueff (A) (eV)f | 2.52 | 2.48e | 2.19 | 2.22e |
aEstimated from the cyclic voltammograms (see Supplementary Fig. 3 for details). The values were calibrated using the energy level of ferrocene/ferrocenium (Fc/Fc+ vs. Ag/AgCl/1 M KCl measured under identical conditions) as the reference.
bDetermined by measuring the distances between the centroid of the ten atoms of the bithiophene in the donor and the mean plane for the eight quinoid carbons in the acceptor in the single-crystal structures.
cDetermined from ρ–T plots using the Arrhenius equation.
dCalculated by OpenMX38,39 as a sum of dispersions for the bonding and antibonding bands between donor HOMO and acceptor LUMO (i.e., WB and WA, respectively) and energy gap between bonding and antibonding bands (i.e., Eg), if present (i.e., bandwidth W = WB + WA + Eg).
eStructural data with major occupancy were used in the calculations for 2O–F2 and 2S–F2.