N-Methyl-4,4′-bipyridinium andN-Methyl-N′-oxide-4,4′-bipyridinium Bismuth Complexes - Photochromism and Photoluminescence in the Solid State

N-Methyl-4,4′-bipyridinium andN-Methyl-N′-oxide-4,4′-bipyridinium Bismuth Complexes - Photochromism and Photoluminescence in the Solid State