Subcomponent self-assembly of circular helical Dy 6 (L) 6 and bipyramid Dy 12 (L) 8 architectures directed via second-order template effects.

In situ metal-templated (hydrazone) condensation also called subcomponent self-assembly of 4,6-dihydrazino-pyrimidine, o -vanillin and dysprosium ions resulted in the formation of discrete hexa- or dodecanuclear metallosupramolecular Dy ₆ (L) ₆ or Dy ₁₂ (L) ₈ aggregates resulting from second-order template effects of the base and the lanthanide counterions used in these processes. XRD analysis revealed unique circular helical or tetragonal bipyramid architectures in which the bis(hydrazone) ligand L adopts different conformations and shows remarkable differences in its mode of metal coordination. While a molecule of trimethylamine acts as a secondary template that fills the void of the Dy ₆ (L) ₆ assembly, sodium ions take on this role for the formation of heterobimetallic Dy ₁₂ (L) ₈ by occupying vacant coordination sites, thus demonstrating that these processes can be steered in different directions upon subtle changes of reaction conditions. Furthermore, Dy ₆ (L) ₆ shows an interesting spin-relaxation energy barrier of 435 K, which is amongst the largest values within multinuclear lanthanide single-molecular magnets.
Competing Interests: The authors declare no conflict of interest.
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