1,1'-Bis(3-sulfopropyl)-4,4'-bipyridinium dihydroxide, bis (inner salt) 4,4'-Bipyridinium, 1,1'-bis(3-sulfopropyl)-, dihydroxide, bis (inner salt) 77951-49-6 N,N'-Dipropyl-4,4'-bipyridinium sulfonate Pvs-4,4'