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Acceptor-donor-acceptor π-extended systems based on α-dithiophenetetrathiafulvalene (α-DT-TTF): Facile synthesis and photoconductivity studies

Velho, M. ; Oliveira, A. ; Serra, J. ; Alcácer, L. ; Avó, João Avó ; Almeida, M. ; Belo, D. ; Alves, H. ; Charas, A.

Dyes and Pigments Vol. 204, Nº 1, pp. 110475 - 110475, August, 2022.

ISSN (print): 0143-7208
ISSN (online): 1873-3743

Scimago Journal Ranking: 0,83 (in 2020)

Digital Object Identifier: 10.1016/j.dyepig.2022.110475

π-Extended derivatives of the electron donor (D) α-dithiophenetetrathiafulvalene (α-DT-TTF) were prepared for
the first time. The compounds consisting of α-DT-TTF covalently linked to N-alkylated phthalimides (Phth) or
thieno[3,4-c]pyrrole-4,6-dione (TPD), as the acceptors (A), in a A-D-A arrangements, were synthesized through
microwave-assisted Stille cross-coupling reactions. DFT calculations reveal that the α-DT-TTF unit is coplanar
with the TPD plane while a light twist occurs with the Phth end-unit, causing highly planar conjugated cores
which are favorable for stacking and intermolecular charge transport. The A-D-A molecular design leads to redshifted absorption spectra, in comparison with α-DT-TTF, and accessible reduction potentials, as indicated by
electrochemical studies. Finally, photoconductivity in the UV–visible, up to 550 nm, was measured in crystals of
one of the new compounds with the acceptor phthalimide. This work opens the way for the synthesis of new
α-DT-TTF derivatives which can have applications in the optoelectronics field.