Synthesis and properties of π-extended triads (A2D) derived from tetrathiafulvalene (TTF) and tetracyano-p-quinodimethane (TCNQ)

A new series of electroactive triads (10a–c) has been prepared by Knoevenagel condensation of formyl-containing π-extended TTFs (9a–c) to a suitably functionalized dimer (8) derived from the electron acceptor TCAQ. The electronic spectra of the triads (10a–c) show the presence of an intramolecular charge transfer (ICT) band from the donor π-extended TTF unit to the conjugated carbonyl groups. Theoretical calculations at the semiempirical PM3 level predict different geometrical structures for the triads which rule out a through space electronic interaction between the donor (π-extended TTF) and acceptor (TCAQs) moieties. Cyclic voltammetric measurements reveal the amphoteric behaviour of triads 10a–c and a negligible electronic interaction between the redox chromophores.