Recent advances in development of bibenzo[c]thiophene derivatives for application in functional materials

1,1′- and 4,4′-bibenzo[ c ]thiophenes as the 1,1′-dimer and 4,4′-dimer of benzo[ c ]thiophene, respectively, have gained more and more attention in recent years because of pioneering challenge to the development of facile and efficient synthetic method and their attractive photophysical and electrochemical properties to be a promising fluorophore and photosensitizer for highly efficient bioimaging, phototheranostics, and optoelectronic devices. Thus, this review is focused on development of bibenzo[ c ]thiophene derivatives and their potential as a π-building block for creating new functional materials. First, synthetic methods for 1,1′- and 4,4′-bibenzo[ c ]thiophene derivatives, and their photophysical and electrochemical properties such as photoabsroption, fluorescence, and redox properties and HOMO and LUMO energy levels are discussed. Moreover, we present not only a practical application of bibenzo[ c ]thiophene unit to optoelectronic devices and fluorescence bioimaging and phototherapy bust also creation of a new-type functional dye material composed of bibenzo[ c ]thiophene skeleton.