Syntheses, Solid State Structures, and Electrical Properties of Oxadiazole-Based Oligomers with Perfluorinated Endgroups

A series of four new oligomers with oxadiazole rings and perfluorinated endgroups was synthesized, utilizing ring closure and coupling reaction procedures that we developed to be compatible with this family of compounds. Three shorter oligomers (three and four rings) crystallize readily and show rigid well-defined structures with close π interactions as determined by X-ray crystallography and thus are a suitable basis for further development as organic semiconductors. Reduction potentials (E1/2) are at or slightly more negative than –1.1 V versus Ag/AgCl. The longest of the oligomers, with a terthiophene core, showed hole mobility in a field-effect transistor of 0.002 cm2/Vs and a threshold voltage well into accumulation. On the basis of electrochemical redox potentials, we expect that elaboration of this oligomer motif with further electron-withdrawing groups will ultimately lead to n-channel organic semiconductors.