| Name of the molecules under study | R1 | R2 | R3 |
| HM-I | -H | -H | -H |
| HM-II | -NO2 | -H | -H |
| HM-III | -NO2 | -NO2 | -H |
| HM-IV | -NO2 | -H | -NO2 |
| HM-V | -H | -H | -NO2 |
| HM-VI | -H | -NO2 | -H |