Energy-level modulation of organic alkynes by click chemistry

A series of novel donor–acceptor chromophores have been successfully synthesized in excellent yield by metal-free [2+2] click chemistry, which was effective in the energy-level modulation. Structures of the conjugated compounds were fully characterized by NMR, IR, and MS. By introducing TCNE, TCNQ, F4-TCNQ click monomers, we obtained energy-level tunable materials in high solubility, which was beneficial for processing. It has been demonstrated that the absorption characteristics of all the newly prepared compounds have been strongly bathochromically shifted with an end-absorption far into the near infrared region due to the efficient intramolecular charge-transfer (CT) interaction. The electrochemical properties have been studied by cyclic voltammograms indicating good agreement between the electrochemical and optical band gaps determined by the end absorption.