Conjunction of chirality and slow magnetic relaxation in the supramolecular network constructed of crossed cyano-bridged $Co^{II}−W^{V}$ molecular chains

The addition of chiral 2,2'-(2,6- pyridinediyl)bis(4-isopropyl-2-oxazoline) ( i Pr-Pybox) to a self-assembled $Co^{II}-[W^{V}(CN)_{8}]$ magnetic system gives two enantiomorphic cyano-bridged chains, ${[Co^{II}((S,S)-iPr-Pybox)(MeOH)]_{3}[W^{V}(CN)_{8}]_{2}\cdot 5\cdot 5MeOH\cdot 0.5H_{2}O}_{n}$ and ${[Co^{II}((R,R)-iPr-Pybox)(MeOH)]_{3}[W^{V}(CN)_{8}]_{2}\cdot 5\cdot 5MeOH\cdot 0.5H_{2}O}_{2}(1-RR)$. Both compounds crystallize with a structure containing a unique crossed arrangement of one-dimensional chains that form a microporous supramolecular network with large channels (14.9 $\dot{A}$ × 15.1 $\dot{A}$ × 15.3 $\dot{A}$) filled with methanol. The investigated materials exhibited optical chirality, as confirmed by natural circular dichroism and UV - vis absorption spectra. 1-(SS) and 1-(RR) are paramagnets with cyano-mediated $Co^{II}-W^{V}$ magnetic couplings that lead to a specific spin arrangement with half of the $W^{V}$ ions coupled ferromagnetically with their $Co^{II}$ neighbors and the other half coupled antiferromag- netically. Significant magnetic anisotropy with the easy axis along the [101] direction was confirmed by single-crystal magnetic studies and can be explained by the single-ion anisotropy of elongated octahedral $Co^{II}$ sites. Below 3 K, the frequency-dependent χM′′(T) signal indicated slow magnetic relaxation characteristic of single-chain magnets.