By comparing the absorption intensity of all complexes in DMF, the molar absorption coefficient  at ~392 nm was maximum in complex 3 (392 ~45,700 M -1 cm -1 ) while the intensity decreases as the size of the ancillary ligand was reduced from Br (392 ~38,900 M -1 cm -1 ) to Cl (392 ~31,100 M -1 cm -1 ) (Figure ). As expected, the absorption coefficient at 392 nm was much lower in the ligand (392 ~13,200 M -1 cm -1 ). The difference in the absorption intensity at lower energy level for the complexes as compared to the ligand confirms the complexation of the bismuth salt with ligand. Moreover, the change in absorption coefficient for the different complexes in DMF further suggests the contribution of ancillary ligands in controlling the ground state absorption. The absorption spectra of complexes 1-3 and L are similar to each other BiBr3 and BiI3 at 375 nm along with a weak absorbing tail for BiCl3 (350-410 nm) (Figure ).