Bridged cyanine dyes. Part 2 . 1-(N-methyl-2-benzothiazolylinio)-3-(N-methyl-2-benzothiazolylene) and 1-(N-methyl-4-pyridinio)-3-(N-methyl-4-pyridylene)cyclopenta-1,4-dienes with fused rings

1,3-Bis(N-methyl-4-pyridyl)- and 1,3-bis(N-methyl-2-benzothiazolyl)-propane diiodides react with 1,2-cyclohexanedione, tetrachloro-1,2- and -1,4-benzoquinone, 2,3-dichloronaphthoquinone, 3,4-dichloromaleimide and 2,3-dichloroquinoxaline to give novel fused ring bridged cyanine dyes.