The synthesis and property investigation of π-bridged 9,9′-bifluorenylidene ladder as an electron acceptor

An efficient synthesis method has been described to achieve a new ladder-type conjugated molecule: π-bridged 9,9′-bifluorenylidene dimer (BBF). Theoretical calculations, absorption spectroscopy, electrochemistry, and fluorescence quenching experiments have been employed to reveal that a ladder-type connection of BBF has all 9,9′-bifluorenylidene subunits to 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.