Table 3. Calculated Energies (Hartree), Energy Differences (kcal/mol) between the Cis- and Trans-Isomers of AzoFL, DFDZ, and DZ and Their Respective Dipole Moments (Debye), Respectively.
| compound | methoda | Etrans | Ecis | Ecis–transg | μ (trans) | μ (cis) |
|---|---|---|---|---|---|---|
| AzoFL | AM1b | 0.261988 | 0.254685 | –4.58 | 0.17 | 2.99 |
| DFTc | –1111.176069 | –1111.150053 | +16.33 | 0.00 | 3.12 | |
| DFDZ | AM1b | 0.049665 | 0.033056 | –10.4 | 0.00 | 0.66 |
| HFd | –307.595444 | –307.593029 | +1.52 | 0.00 | 0.17 | |
| HFe | –307.595444 | –307.593029 | +1.52 | 0.00 | 0.17 | |
| HFf | –307.673508 | –307.670734 | +1.74 | 0.00 | 0.18 | |
| DFTc | –309.033536 | –309.036420 | –1.81 | 0.00 | 0.22 | |
| DZ | AM1b | 0.050244 | 0.051651 | +0.88 | 0.00 | 2.70 |
| HFd | –110.006960 | –109.994657 | +7.72 | 0.00 | 3.37 | |
| DFTc | –110.651970 | –110.641101 | +6.82 | 0.00 | 3.20 |
a
The symmetry of trans-DZ and DFDZ in different methods are C2h, C2v for cis-DZ and DFDZ; C2 for both the trans- and cis-AzoFL.
b
Semiempirical AM1 method using predefined ZDO basis set.
c
B3LYP/6-31+G(d,p) basis set.
d
6-31+G(d,p) basis set.
e
6-31++G(d,p) basis set.
f
6-311+G(d,p) basis set.
g
The negative values of energy difference in respective cases indicate the cis-preference over trans-isomer.