Abstract Three bismuth complexes based on N-methyl-4, 4′-bipyridinium (hMV+),(hMV)[Bi (hMV) Cl 5](1), and N-methyl-N′-oxide-4, 4′-bipyridinium (MVO+),[Bi (MVO) X 4 (dmso)]· dmso [X= Cl (2), Br (3)], are reported. All three compounds show luminescence in the solid state with maxima at 545 nm (yellow for 1) and 560 nm (orange for 2 and 3) with quantum yields up to 10%. Upon UV irradiation, 1 undergoes a color change from white to blue ...