A family of solution-processable macrocyclic and open-chain oligothiophenes with atropoisomeric scaffolds: structural and electronic features for potential energy applicationsElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nj01501a

• Main Authors: Quartapelle Procopio, E, Benincori, T, Appoloni, G, Mussini, P. R, Arnaboldi, S, Carbonera, C, Cirilli, R, Cominetti, A, Longo, L, Martinazzo, R, Panigati, M, Pò, R
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c7nj01501a

FeCl 3 oxidation of the racemate of C 2 symmetric, inherently chiral, sexithiophene monomer 1 (2,2′-bis(2,2′-bithiophene-5-yl)-3,3′-bithianaphthene) affords a mixture of cyclic oligomers, from the prevailing dimer to traces of the pentamer. The oligomers are constituted by mixtures of stereoisomers which are two for dimer 2 , four for trimer 3 and six for tetramer 4 . Cyclooligomers 2 and 3 could be separated by chromatography, while 4 was synthesized by ring closure of open chain dimer 2a , prepared in turn by controlled coupling of the anion of racemic 1 . The optical properties of open-chain stereoisomer 2a and tetramer 4 have been compared with those of 2 and 3 respectively. The macrocyclic oligomers have been tested as donor materials in bulk heterojunction solar cell prototypes both as a crude mixture resulting from oxidation of 1 and as a single oligomer. Theoretical calculations support the photophysical properties of these new materials. Cyclic and linear inherently chiral oligothiophenes have been employed as donors in bulk heterojunction solar cells with fullerenes as acceptors.