Electron-Rich Pyrroloindacenodithiophenes: Synthesis, Characterization, and Spectroscopic Studies

N-Alkyl substituted pyrroloindacenodithiophene (PIDT) and their phenyl substituted derivatives were synthesized. Their single-crystal structures and electrochemical and spectroscopic properties were investigated. Experimental results showed PIDT displayed strong electron-donating properties, reversible redox behaviors, and strong fluorescence and could be controlled to oxidize to radical cation and dication with distinctive optical changes. These attractive properties demonstrated the potential applications of PIDT in the field of switches, molecular machines, and information memories.