First intramolecular charge resonance band observed at room temperature in solution by steady photolysis of 1,3-bis(4-(4-nitrostyryl)pyridinium)propane tetraphenylborate

1,3-Bis(4-nitrostyrylpyridinium)propane tetraphenylborate salt showed a remarkable color change upon steady photoexcitation due to photoinduced electron transfer. It gave two stable charge resonance bands with peaks at 948 and 1742 nm in acetonitrile at room temperature. During storage in the dark, the former decayed monotonically, while the latter gradually changed its shape and showed a peak at 1505 nm after 3 h. The 948 and 1742–1505 nm bands were attributed to sandwich-type and partially overlapped configurations of intramolecular dimer radical cations, respectively.