Molecular electron spin qubits offer atomic-level tunability and room-temperature quantum coherence. Their integration into engineered solid-state matrices can enhance performance toward ambient quantum information technologies. Herein, we demonstrate covalent organic frameworks (COFs) as programmable matrices for stable organic radical qubits, allowing strategic optimization of spin-phonon and spin–spin interactions. Using two classic boronate-ester frameworks, COF-5 and COF-108, to host semiquinone-like radical qubits, we achieve an ultralong spin relaxation time (T1 > 300 μs) at 298 K, which outperforms most molecular qubits and rivals inorganic spin defects. The suppression of spin relaxation is attributed to rigid and neutral structures as well as carbon-centered spin distributions that effectively weaken spin-phonon coupling. Employing dynamical decoupling methods to both COFs improves their quantum coherence and enables room-temperature detection of nuclear spins, including 1H, 11B, and 13C. Our work establishes COFs as designer quantum materials, opening new avenues for quantum sensing of nuclear spins at room temperature.
Sun et al. (2025) studied this question.