Synthesis of new two-dimensional conjugated diketopyrrolopyrrole polymers by inverse-electron demand Diels-Alder (iEDDA) reaction

Abstract

Inverse electron demand Diels-Alder reaction has been a fascinating reaction for various applications including total synthesis, bioorthogonal post-polymerization modification, and synthesis of organic material units. With inverse electron demand Diels-Alder reaction, easy modification of polymer structure seems possible. In this works, I synthesized diketopyrrolopyrrole based polymer with tetrazine unit (PDPPTTzT) and with benzo[d]phthalazine unit (PDPPTBPzT). Benzo[d]phthalazine unit can introduce additional conjugation in a vertical direction to the main backbone conjugation to the polymer and can be easily synthesized with inverse electron demand Diels-Alder reaction. Thus, PDPPTBPzT can be synthesized easily with two-dimensional conjugated polymer structure. This structure can have stronger π-π interaction between polymers for better performance. Both of the polymers had narrow optical bandgap of 1.44 eV which can allow smaller injection barrier for both hole and electron charge carriers. Moreover, for future studies, the synthesis of benzo[d]phthalazine unit with post-polymerization inverse electron demand Diels-Alder reaction will be tested to show the potential of the post-polymerization modification. Thus, studies of PDPPTTzT and PDPPTBPzT polymers provided future design strategy.