Synthesis and properties investigation of π-bridged 9,9’-bifluorenylidene ladder as electron acceptors

The efficient synthesis has been described to achieve a new class of ladder-type conjugated molecule, π-bridged 9,9’-bifluorenylidene dimer (BBF). The theoretical calculations, absorption spectroscopy, electrochemistry, and fluorescence quenching experiments are employed to reveal that a ladder-type connection of BBF has all 9,9’-bifluorenylidene subunits contribute to its frontier orbitals, with good electron acceptability. We also demonstrated that such a π-bridged insertion exhibits significant effects on photophysical and electrochemical properties compared with its macrocyclic counterpart.