Ladderizing Functional Organic pi-Systems

The main research focus of the Fang group is conjugated ladder molecules and macromolecules, in which the entire molecular backbone is fused and π-conjugated. The structures of these ladder-type systems mimic the constitution of graphene nanoribbons, endowing them with promising electronic, optical, and mechanical properties. These unique fused-ring constitutions, however, also impose formidable synthetic and processing challenges on the development and application of ladder polymers. To resolve this dilemma, we aimed to integrate the synthetic versatility and processability of conventional synthetic polymers with the seemingly incompatible features of rigid ladder polymers, through innovative fundamental chemistry and molecular engineering approaches. These strategies include the formation of dynamic covalent bonds, the installation and cleavage of labile function-masking groups, and the employment of non-covalent intramolecular interactions. Through these approaches, we have achieved the efficient synthesis and property investigation of defect-free, benzo[k]tetraphene-derived ladder oligomers and polymers, solution-processing and application of solvent resistant quinacridone-derived ladder polymers, boron-nitrogen coordinate bond-bridged ladder type small molecules, as well as the synthesis and gas storage application of porous ladder polymer networks. Development of these new chemistries enabled the applications of ladder type organic materials on multiple fronts.