Synthesis and properties of pi-extended triads (A(2)D) derived from tetrathiafulvalene (TTF) and tetracyano-p-quinodimethane (TCNQ)

A new series of electroactive triads (10a-c) has been prepared by Knoevenag el condensation of formyl-containing pi -extended TTFs (9a-c) to a suitably functionalized dimer (8) derived from the electron acceptor TCAQ. The elec tronic spectra of the triads (10a-c) show the presence of an intramolecular charge transfer (ICT) band from the donor pi -extended TTF unit to the con jugated carbonyl groups. Theoretical calculations at the semiempirical PM3 level predict different geometrical structures for the triads which rule ou t a through space electronic interaction between the donor (pi -extended TT F) and acceptor (TCAQs) moieties. Cyclic voltammetric measurements reveal t he amphoteric behaviour of triads 10a-c and a negligible electronic interac tion between the redox chromophores. (C) 2001 Elsevier Science Ltd. All rig hts reserved.