Recently, photoinduced electron transfer (PET) reactions have been foc
used on the behavior of radical-ion species. Here, we review the PET r
eactions of azo compounds, especially azoalkanes. Ground state interac
tions between azoalkanes and cationic salts have been investigated. On
the basis of these results, studies of CT band excitation and PET rea
ctions are developed. There are two types of the PET reactions. One is
the electron transfer from the excited molecules of azoalkanes to the
ground stale electron acceptor molecules, and the other is the electr
on transfer from the ground stale molecules of azoalkanes to the excit
ed electron acceptor molecules. Products via cation intermediates are
given from the reactions of acyclic azoalkanes and rearranged products
are produced from the reaction of cyclic azo compounds. In many cases
, it is known the back electron transfer plays very important role in
the PET reaction.