Semiconducting Covalent Organic Frameworks Based on Spin-Delocalized Trioxotriangulene Neutral Radicals

Electrically conductive two-dimensional covalent organic frameworks (2D COFs) have emerged as a versatile class of crystalline porous polymers with promising applications in electronics and energy storage. However, high electrical conductivity generally relies on post-synthetic doping to generate charge carriers, which can compromise crystallinity, porosity, and structural homogeneity. Persistent neutral radical conductors provide an attractive alternative, as their unpaired electrons can generate free charge carriers without the need for counterions. Nevertheless, the incorporation of highly spin-delocalized π-radicals into COFs remains largely unexplored. Herein, we report the design and synthesis of imine-linked 2D COFs incorporating spin-delocalized trioxotriangulene (TOT) neutral radicals through complementary synthetic approaches. Direct use of a TOT radical derivative bearing amino groups affords a highly crystalline framework (TOT-COF-H) that exhibits semiconducting behavior (σ_RT = 1.2 × 10^-4 S cm^-1), a reduced band gap (E_g = 1.09 eV), and a low activation energy (0.24 eV). This work demonstrates a viable strategy for integrating spin-delocalized neutral radical building blocks into COFs, enabling the development of intrinsically conductive, porous, and crystalline organic frameworks without the need for extrinsic doping.