A Stable, NH-Containing Chiral Nanographene: An Electroactive N-Doped π-System for Chiroptics and Spin-Selective Transport

The integration of nitrogen atoms into chiral nanographenes (c-NGs) offers a powerful strategy for designing chiral materials with programmable electronic and chiroptical responses. However, the preparation of stable N-doped c-NGs featuring free NH groups─an essential chemical handle─remains a major synthetic challenge. Herein, we report a highly stable N-doped c-NG (NHNG) featuring a free NH moiety, which enables comprehensive investigation of not only its structural but also its optical, redox, electronic, and spintronic properties. X-ray crystallography reveals an intriguing π-scaffold combining three coexisting topologies: two helical and one saddle-shaped. By virtue of its extended conjugation, NHNG displays strong visible-light absorption (ε = 170,000 M⁻¹ cm⁻¹) and a rich electrochemical profile, with four oxidations leading to persistent cationic species that exhibit sharp near-infrared absorptions. In parallel, time-resolved microwave conductivity measurements demonstrate notable photoconductivity (ϕΣμmax = 3.0 × 10⁻⁵ cm² V⁻¹ s⁻¹). Owing to their robustness, the corresponding M- and P-enantiomers were resolved and found to exhibit pronounced chiroptical properties, with |gabs| = 4.2 × 10⁻³ and |glum| = 2.2 × 10⁻³. Remarkably, both enantiomers also display spin-selective charge transport via the chiral-induced spin selectivity effect, reaching spin-polarization values of ∼80%─among the highest reported for single-molecule-based π-conjugated spin filters. Altogether, these findings render NHNG a multifunctional chiral platform for next-generation optoelectronic, spintronic, and chiroptical applications.