A two-faced 'Janus-like' unimolecular rectifier exhibits rectification reversal

A molecule containing an electron donor (pyrene, Py), an insulating tetramethylene bridge, an electron acceptor (perylenebisimide, PBI) and a bis-decyl swallowtail with two terminal thioesters was studied for its electrical rectification as a Langmuir-Blodgett (LB) monolayer between two Au electrodes at room temperature (over a 8 month period, the thioester terminations chemisorbed partially (about 15%) onto the bottom Au electrode). At lower bias (<+/-1.5 Volts), the direct current was greater at positive than negative bias; at higher bias (+/-2.0 and +/-2.5 Volts), the conduction was larger at negative bias: this 'Janus' switching was repeatable when the bias ranges were changed. At constant bias range, repeated scans showed a gradual decrease in conductivity. Ancillary characterization data are reported.