Unusual electronic absorption changes in the 800-2200 nm region by intramolecular dimer radical cations from photoirradiated meso-2,4-bis[4-(4-nitrostyryl)pyridinium] pentane ditetraphenylborates during storage in the dark

Electronic absorption spectra were remarkably changed in the broad near-inf rared region for photoirradiated meso-2,4-bis[4-(4'-nitrostyryl) pyridinium ]pentane ditetraphenyl-borates during storage in the dark, which was attrib uted to conformational changes of the intramolecular dimer radical cations between sandwich and partially overlapped types.