All-optical room-temperature spin coherence of aqueous asymmetrically chelated Cu(II) for chemoselective discrimination
Year: 2026
Type: preprint
Abstract: Harnessing molecular electron spins as responsive quantum sensors in ambient water requires bridging ultrafast all-optical readout with selective chemical recognition. Here, we overcome the intrinsic magneto-optical sluggishness of 3d transition-metal complexes--which previously restricted all-optical detection to high concentrations of ~1 M--through a coordination-driven symmetry-breaking strategy. Coordinating aqueous Cu(II) with EDTA imposes a non-centrosymmetric ligand field with enhanced metal-ligand covalency, relaxing Laporte restrictions and amplifying d-d transition dipole moments. This design enables room-temperature all-optical initialization and readout of electron spin coherence down to 100 μM with an apparent dephasing time T_2^*~0.54 ns. Crucially, the chelated complex chemoselectively discriminates amino acid biomolecules: histidine binding induces a pronounced, concentration-dependent prolongation of T_2^* to ~0.8 ns, whereas glycine produces no measurable effect. These results transform spin dephasing into a chemically informative observable, opening avenues toward microwave-free, analyte-responsive quantum sensing in complex aqueous environments.
Source: arXiv (Cornell University)
Institutions: East China Normal University, Shanxi University
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223004325