Chemical control of spin propagation between heterometallic rings

We present a synthetic, structural,theoretical, and spectroscopicstudy of a family of heterometallic ringdimers which have the formula[{Cr7NiF3ACHTUNGTRENUNG(Etglu)ACHTUNGTRENUNG(O2CtBu)15}2ACHTUNGTRENUNG(NLN)],in which Etglu is the pentadeprotonatedform of the sugar N-ethyl-d-glucamine,and NLN is an aromatic bridgingdiACHTUNGTRENUNGimine ligand. By varying NLN we areable to adjust the strength of the interactionbetween rings with the aim ofunderstanding how to tune our systemto achieve weak magnetic communicationbetween the spins, a prerequisitefor quantum entanglement. Micro-SQUID and EPR data reveal that themagnetic coupling between rings ispartly related to the through-bond distancebetween the spin centers, butalso depends on spin-polarizationmechanisms and torsion angles betweenaromatic rings. Density functionaltheory (DFT) calculations allow usto make predictions of how such chemicallyvariable parameters could beused to tune very precisely the interactionin such systems. For possible applicationsin quantum information processingand molecular spintronics, suchprecise control is essential.