Supramolecular dyads as photogenerated qubit candidates

Molecular spin qubits have the advantages of synthetic flexibility and amenability to be tailored to specific applications. Among them, chromophore–radical systems have emerged as appealing qubit candidates. These systems can be initiated by light to form triplet–radical pairs that can result in the formation of quartet states by spin mixing. For a triplet–radical pair to undergo spin mixing, the molecular bridge joining the spin centres must permit effective spin communication, which has previously been ensured using covalent, π-conjugated linkers. Here we used perylenediimides and nitroxide radicals designed to self-assemble in solution via hydrogen bonding and observed, using electron paramagnetic resonance spectroscopy, the formation of quartet states that can be manipulated coherently using microwaves. This unprecedented finding that non-covalent bonds can enable spin mixing advances supramolecular chemistry as a valuable tool for exploring, developing and scaling up materials for quantum information science. Molecular approaches in quantum information science are highly promising, but the synthesis and scale-up of suitable covalently linked moieties represent major challenges. Here it is demonstrated that efficient spin mixing between photogenerated spin centres is possible through hydrogen bonds, advancing supramolecular chemistry as a valuable tool to address these challenges.