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Updated: May 17, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Long-lived nuclear singlet order in near-equivalent 13C spin pairs
Giuseppe Pileio1, Joseph T Hill-Cousins, Sam Mitchell
1School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK. g.pileio@soton.ac.uk
Abstract:
Molecules that support (13)C singlet states with lifetimes of over 10 min in solution have been designed and synthesized. The (13)C(2) spin pairs in the asymmetric alkyne derivatives are close to magnetic equivalence, so the (13)C long-lived singlet states are stable in high magnetic field and do not require maintenance by a radiofrequency spin-locking field. We suggest a model of singlet relaxation by fluctuating chemical shift anisotropy tensors combined with leakage associated with slightly broken magnetic equivalence. Theoretical estimates of singlet relaxation rates are compared with experimental values. Relaxation due to antisymmetric shielding tensor components is significant.
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