An Error in Determination of Photoinduced Electron Transfer Rates in Langmuir-Blodgett Films

In Langmuir-Blodgett (LB) films consisting of viologen (V2+)-pyrene (Py) dyads, the accumulation of viologen cation radical (V+·) was observed during UV irradiation under N2. The additional quenching due to energy transfer by the colored V+· resulted in an error in determination of photoinduced electron transfer rates between the V2+ and Py moieties in the LB films. This type of error can be generally expected in LB films and self-assembled monolayers.