Synthesis and photophysical properties of alternating donor-acceptor conjugated nanorings

Herein, we report the design and synthesis of alternating donor-acceptor nanorings [3]C-NA and [4]C-NA, along with a reference linear molecule [3]L-NA, via electrochemical oxidation-induced reductive elimination of alkynyl platinum(II) complexes. Unlike [3]L-NA, which exhibits charge defects at its end-groups, the cyclic structures of [3]C-NA and [4]C-NA facilitate enhanced electron delocalization, enabling efficient charge transfer in low-polarity toluene. In the polar solvent dichloromethane (DCM), the increased flexibility of [4]C-NA promotes intramolecular charge transfer and suppresses charge recombination. The observed faster intramolecular charge transfer and slower charge recombination rates in these nanoring acceptor materials suggest their potential for improving the power conversion efficiency of organic solar cells, providing valuable insights for the design of nanoring acceptor materials.