Stacked oligothiophenes: New materials and models for charge carriers in polythiophenes

ORGN 288

David M. Collard, david.collard@chemistry.gatech.edu and Kurt M. Knoblock, david.collard@chemistry.gatech.edu. School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400
Electrical conduction and light emission of conjugated organic polymers requires migration of delocalized charge carriers and excitons along the conjugated chains and through π-stacks. Linear oligoarenes are often studied as models for segments of polymer chains. However, photophysical and electrochemical studies of these oligomers in solution neglect the presence of interactions between polymer chains. We have prepared model compounds for conjugated polymers in which oligomers are permanently held in a cofacial stacked arrangement. These are based on: (i) pseudopara-substituted [2.2]-paracyclophane, and (ii) thieno-fused bicyclo[4.4.1]undecanones. These provide platforms to study the effect of pi-stacking on the electronic properties of the conjugated oligomers relative to unstacked analogs. Here we discuss the synthesis and properties of models for excited states, and polaronic and biopolaronic charge carriers, in polythiophenes.