Studies on the Magnetic Ground State of a Spin Möbius Strip

Abstract

Here we report the synthesis, structure and detailed characterisation of three n-membered oxovanadium rings, Na${}_n$[(V=O)${}_n$Na${}_n$(H${}_2$O)${}_n$($\alpha$, $\beta$, or $\gamma$-CD)${}_2$]$m$H${}_2$O (n = 6, 7, or 8), prepared by the reactions of (V=O)SO${}_4$$\cdot$$x$H${}_2$O with $\alpha$, $\beta$, or $\gamma$-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 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.

8 pages, 8 figures, accepted for publication in Chemistry - A European Journal