Ring-forming transformation associated with hydrazone changes of hexadecanuclear dysprosium phosphonates

Abstract

{Dy₁₆(μ₆-C₁₀H₇PO₃)₂(μ₅-C₁₀H₇PO₃)₈(spch)₈(μ₃-OH)₂(μ₂-OH)₂(μ₂-AcO)₆(μ₃-COO)₂(DMF)₂(H₂O)₆}·0.5CH₃OH·4.5H₂O (1) and {Dy₁₆(μ₅-C₁₀H₇PO₃)₄(μ₃-C₁₀H₇PO₃)₁₂(μ₂-C₁₀H₇PO₃H)₈(opch)₄(DMF)₈(MeOH)₄}·2.5CH₃OH·3H₂O (2), where H₂spch is ((E)-N′-(2-hydroxybenzylidene)pyrazine-2-carbohydrazide, C₁₀H₇PO₃H₂ is 1-naphthylphosphonic acid and H₂opch is (E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide, were successfully synthesized by varying the hydrazone ligands in the Dy-phosphonate system. It is important that the ellipsoidal core experiences a ring forming structural transformation to the supramolecular square motif upon the incorporation of an ortho-methoxy substituent into the hydrazone. Alternating-current (ac) magnetic susceptibility studies of 1 and 2 suggest that similar single molecule magnet behaviors occur for these two complexes. The result represents an effective molecular assembly tactic to develop highly complicated lanthanide coordination clusters through the multicomponent self-assembly of the coalescence of phosphonate- and hydrazone-based ligands and metal salts.