Symmetry-breaking chelation enables room-temperature all-optical spin coherence readout of aqueous Cu(II) for chemoselective discrimination
Abstract
Optical initialization and readout of molecular electron spins in water remains challenging for 3d transition-metal complexes. Their Laporte-forbidden d-d transitions yield weak transition dipole moments, so optical spin detection in aqueous Cu(II) previously required ~1 M concentrations. Here we overcome this constraint through symmetry-breaking chelation. Coordinating 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 enhances absorption and magnetic circular dichroism by 7.3- and 5.6-fold, enabling ultrafast spin readout down to 100 μM with an apparent dephasing time T2^*~0.54 ns. As a proof-of-concept for selective molecular-spin sensing, histidine addition extends T_2^* to ~0.8 ns in a concentration-dependent manner, whereas glycine produces no measurable effect. These results show that symmetry breaking provides a strategy to create molecular spin-photon interfaces, opening avenues toward all-optical, analyte-responsive quantum sensing in water.
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BibTeX
@misc{li2026symmetrybreaking,
title = {{Symmetry-breaking chelation enables room-temperature all-optical spin coherence readout of aqueous Cu(II) for chemoselective discrimination}},
author = {Jinlei Li and Qiaoyun Wu and Qiaoqiao Shao and Zhubin Hu and Haitao Sun and Zhenrong Sun and Donghai Feng},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24925},
eprint = {2610.24925},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24925},
}
RIS
TY - UNPB
TI - Symmetry-breaking chelation enables room-temperature all-optical spin coherence readout of aqueous Cu(II) for chemoselective discrimination
AU - Jinlei Li
AU - Qiaoyun Wu
AU - Qiaoqiao Shao
AU - Zhubin Hu
AU - Haitao Sun
AU - Zhenrong Sun
AU - Donghai Feng
PY - 2026
DA - 2026/10/18
PB - arXiv
DO - 10.48550/arxiv.2610.24925
UR - https://arxiv.org/abs/2610.24925
AB - Optical initialization and readout of molecular electron spins in water remains challenging for 3d transition-metal complexes. Their Laporte-forbidden d-d transitions yield weak transition dipole moments, so optical spin detection in aqueous Cu(II) previously required ~1 M concentrations. Here we overcome this constraint through symmetry-breaking chelation. Coordinating 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 enhances absorption and magnetic circular dichroism by 7.3- and 5.6-fold, enabling ultrafast spin readout down to 100 μM with an apparent dephasing time T2^*~0.54 ns. As a proof-of-concept for selective molecular-spin sensing, histidine addition extends T_2^* to ~0.8 ns in a concentration-dependent manner, whereas glycine produces no measurable effect. These results show that symmetry breaking provides a strategy to create molecular spin-photon interfaces, opening avenues toward all-optical, analyte-responsive quantum sensing in water.
ER -