Syntheses, characterizations, and properties of electronically perturbed 1,1'-dimethyl-2,2'-bipyridinium tetrafluoroborates.

[reaction: see text] The syntheses of three new 2,2'-bipyridinium tetrafluoroborate sensitizers are reported. Their preliminary electrochemical and photophysical properties are compared to the properties of the more widely used pyrylium cation sensitizers. In addition, the first examples of triplet-triplet absorption spectra of 2,2'-bipyridinium ions are presented.