Conductivity, interaction and solubility of hetero-bifunctional end-capped beta,beta'-dihexylsubstituted sexithiophenes

Three ,'-dihexylsexithiophenes were synthesized, one without end group modification (T6.1), one with dialdehyde (T6.2) and one with diester (T6.3) end-capping. Their properties were investigated by cyclic voltammetry and Ultraviolet-visible spectroscopy, and it was found that while they were nonconducting in undoped form, the conductivity reached 0.001Scm(-1) (T6.1), 0.017Scm(-1) (T6.2), and 0.003Scm(-1) (T6.3) when doped with iodine vapor. The solubilities of T6.2 and T6.3 in chloroform were excellent, whereas the solubility of T6.1 was low and in line with earlier literature values. Moreover, the studies revealed that T6.2 is also highly soluble in tetrahydrofuran. For the dialdehyde end-capped ,'-dihexylsexithiophene T6.2 association constants for self-association in chloroform and with silica were determined to be 1.6 and 2.3 (mol/kg)(-1), respectively. In contrast, the two other oligothiophenes did not show such associations.