Intramolecular Charge‐Transfer Dynamics in Benzodifuran‐Based Triads

A facile and efficient approach for the synthesis of new conjugated donor-pi-acceptor (D-pi-A) chromophoreshas been developed, in which benzodifuran (BDF) and/or triphenyl amine (TPA) units are the donor moieties,linked by ethylenic bridges to electron-deficient anthraquinone (AQ) and 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) as the acceptor moieties. The resultant triads either with a symmetric A–D–A oran asymmetric D'–D–A structure show intense absorption bands in the visible spectral region due to efficientintramolecular charge transfer (ICT) from the HOMO localized on the BDF core to the LUMO localized on the AQor the TCAQ unit. Electronic interactions between these redox-active components were studied by a combinationof cyclic voltammetry, spectroelectrochemistry, UV-visible and ultrafast transient absorption spectroscopy.Analysis of the femtosecond excited-state dynamics reveal that all triads undergo a rapid charge recombinationprocess which occurs within a few picoseconds, indicating that ethylenic linkers can facilitate electrondelocalization among BDF and AQ/TCAQ units and thus impart effective electronic interactions between the