Studies on the Magnetic Ground State of a Spin Möbius Strip.

Here we report the synthesis, structure and detailed characterisation of three n-membered oxovanadium rings, Na _n[(V=O) _nNa _n(H₂O) _n(α, β, or γ-CD)₂]⋅ m H₂O ( n=6, 7, or 8), prepared by the reactions of (V=O)SO₄⋅ x H₂O with α, β, or γ-cyclodextrins (CDs) and NaOH in water. Their alternating heterometallic vanadium/sodium cyclic core structures were sandwiched between two CD moieties such that O-Na-O groups separated the neighbouring vanadyl ions. Antiferromagnetic interactions between the S=1/2 vanadyl ions led to S=0 ground states for the even-membered rings, but to two quasi-degenerate S=1/2 states for the spin-frustrated heptanuclear cluster. [ABSTRACT FROM AUTHOR]