The charge-transfer and spectral properties of two octithiophenes, namely 4',4''',3'(v),3(v)'-tetra(octylsulfanyl)-2,2':5',2'':5'',2''':5''',2'(v):5'(v),2(v):5(v),2(v)':5(v)',2(v)''-octithiophene and 4,3'',4(v),4(v)''-tetrabromo-4',4''',3'(v),3(v)'-tetra[(R)-2-methylbutylsulfanyl]-2,2':5',2'':5'',2''':5''',2'(v):5'(v),2(v):5(v),2(v)':5(v)',2(v)''-octithiophene, OT1 and OT2, respectively, are characterized by cyclic voltammetry and spectroelectrochemistry under ultradry conditions. The analysis of the voltammetric results shows the formation of up to the dication for both OT1 and OT2 and up to the tetraanion (OT1) and trianion (OT2) anions. The optical properties of the OT1 (2+, 1+, neutral, 1-, 2-) species were probed by in situ UV-vis-NIR spectroelectrochemistry. The calculated standard potentials at the B3LYP/cc-pVTZ level of the theory allowed the rationalization of the experimental electrochemical results. The UV-vis-NIR spectra were successfully compared with the theoretical electronic transitions and oscillator strength data obtained by time-dependent B3LYP/6-31G* calculations. Theoretical redox potentials and optical transitions properties are calculated including "the solvent effect" within the CPCM model. The consistency obtained between experimental and theoretical results indicates the existence of the hypothesized high-spin/high-charge p- and n-doped electronic states for the OT1 and OT2 octithiophenes here studied.

Starting from 4-(octylsulfanyl)-2,2‘-bithiophene, 4-bromo-4‘-(octylsulfanyl)-2,2‘-bithiophene, 4-iodo-4‘-(octylsulfanyl)-2,2‘-bithiophene, 4-bromo-4‘-[(S)-2-methylbutylsulfanyl]-2,2‘-bithiophene, and 4-iodo-4‘-[(S)-2-methylbutylsulfanyl]-2,2‘-bithiophene, a new series of symmetrically β-substituted octithiophenes were synthesized by one-pot oxidative coupling with FeCl3. The octithiophenes obtained are soluble in common organic solvents and show different solvatochromic properties depending on the substitution type. In particular, the bromine atom exerts a positive influence on the supramolecular organization:  the brominated octithiophenes display high filmability, solvatochromism, and CD induced by aggregation (when the chiral 2-methylbutylsulfanyl group is present), properties usually observed for polythiophenes. Density functional theory (DFT) calculations were carried out an a model bithiophene (4-substituted with a methylsulfanyl group) in order to understand the possible mechanism of the growth, the regiochemistry, and the reason for the polymerization leads to an octithiophene.

Six new aminoalkylsulfanyl polythiophenes (PTs), namely PTNHBoc, PTNMeBoc, PTNH2,PTNHMe, PTNMe2, and PTN+Me3, were synthesized. Four of them were obtained through Stille coupling, whereasPTNH2 and PTNHMe were obtained through deprotection via N-Boc precursors. The solubility changes goingfrom the protected amines to the quaternary ammonium salt. All the polymers are soluble in DMSO and DMF.PTNHBoc and PTNMeBoc are also soluble in CHCl3, CH2Cl2, THF, and DMPU; PTNH2 and PTNHMe aresoluble in CH3OH, whereas PTNMe2 and PTN+Me3 are soluble both in CH3OH and in H2O. These PTs show atendency toward microaggregation in solution that does not represent an obstacle to their solubility. NMR, UV-vis,and XRD results prove that they are able to reach very high conjugation lengths and ordered conformations, notonly in the solid state but also in solutions of good solvents