Tunable Quantum Coherence of Polymer-Attached Molecular Spins (PAMS): An Example of Metal-Porphyrin-Centred Four-Arm Star-Like Polymers

Molecular spins, owing to their vast synthetic variety and ease of scalability, have emerged as promising qubits for quantum computation and information processing. However, a major challenge is to disperse the spin moieties into solid matrices in a well-defined and controllable way. Limited success has been achieved in previously developed strategies such as diluting the spin moieties into diamagnetic matrices of crystals, frozen solvents, or metal-organic frameworks. Herein, we present a powerful strategy of tuning the spin-spin coherence and spin-lattice interaction by covalently tethering star-like polymer chains from molecular spins, using metal-coordinated porphyrins as an example. Specifically, we have designed and synthesized a series of four-arms star-like polyesters, each of which contains a copper-porphyrin core serving as a single molecular spin and qubit. We have employed both continuous wave and pulse electron paramagnetic resonance spectroscopy (EPR) to study the impact of chemical composition and chain lengths on the quantum coherence and spin-lattice relaxation of these polymer-attached molecular spins, so-called PAMS, in solid states. The structure-property relationship that we have revealed in the present PAMS polymers will offer insight into molecular design and structural control for constructing ordered arrays of a large number of molecular qubits in the future. [GRAPHICS]