Multicomponent Open‐Shell Donor‐Acceptor Diradical Polymers: Design, Synthesis, and Characterization

Organic semiconductive polymers can be classified into unary, binary, and ternary ones in previous work. The binary polymers based on the donor-acceptor architecture have witnessed significant progress of this field. Conjugated polymers with four or more components have been rarely reported. Exemplified by a ten-component system, we report multi-component polymers P10-FTTPA, P10-FTBT, and P10-FTBBTA. The chemical structure and photothermal conversion performance of them were studied using ¹H NMR, UV-vis-NIR absorption, cyclic voltammetry, electron spin resonance, and photothermal performance testing. The open-shell diradical character increased as the molecular bandgap decreased. P10-FTBBT exhibited reduced fluorescence quantum yield, enhanced open-shell diradical character and photothermal conversion efficiency. Especially, the open-shell diradical of P10-FTTPA, P10-FTBT was attributed to our aggregation-induced radical concept and quinoid-diradical mechanism with the loss of aromaticity and double bonds since 2017 (J. Phys. Chem. C., 2017, 121, 8579-8588), which is different from the recovery of aromaticity mechanism of BBT-diradical (J. Phys. Org. Chem. 2011, 24, 821-832), which is from the outdated Chichibabin diradical since 1907.