Thiophene Donor−Acceptor [2]Rotaxanes

A series of the thiophene donor−acceptor [2]rotaxanes have been synthesized based on the inclusion complexes of cyclobis(paraquat-p-phenylene) (CBPQT4+) with thiophene, bithiophene, and terthiophene. The maximum wavelength of the charge-transfer band strongly depends on the number of thiophene units, while the association constant does not. These donor−acceptor pairs will be fascinating constituents for optoelectronic and electromechanical materials.