Abstract
Functionalized cyclopentadithiophenes 2 and 3 were synthesized and polymerized by anodic coupling, in acetonitrile solution, in the presence of 0.1 M tetraethylammonium perchlorate as supporting electrolyte. The former carries a 16-crown-5-ether ring coplanar to the bithiophene moiety, while a perpendicular 15-crown-5-ether ring is present in the latter. The cyclic voltammogram of poly-2 shows two redox processes at E° = −0.3 and +0.3 V, whereas that of poly-3 consists of a single response at E° = 0.0 V. The difference in electrochemical behavior is attributed to the occurrence of strong polaron π-dimerization in poly-2. The redox potential (E°) of this polymer moves toward more positive values passing from lithium to sodium salts as supporting electrolytes in acetonitrile solution. The redox cycle of poly-3 is instead completely insensitive to the change of the cationic species in solution. EQCM analysis shows that (i) both neutral polymers incorporate one alkaline ion per crown ring, (ii) the p-doping p...
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