Base- and Metal-Dependent Self-Assembly of Lathanide-Organic Coordination Polymers or Macrocycles with Tetradentate Acylhydrazone-based Ditopic Ligands.

Herein, we report a comprehensive study on the lanthanide-directed coordination self-assembly with two bis-tetradentate acylhydrazone ligands H4 L1 and H4 L2 . Multifarious outcomes, which are base- and metal-dependent, were revealed by NMR, ESI-TOF-MS and X-ray crystallography. In the absence of base, bent H4 L1 was assembled into dinuclear double-strand helicate Ln2 (H2 L1 )2 by partially-deprotonated assembly with La, Sm or Eu, while trinuclear Ln3 (H2 L1 )3 with Yb or Lu. For linear H4 L2 , infinite 1D zig-zag metal-organic polymeric chain (Ln2 H2 L2 )n was obtained. However, complete deprotonated L1 and L2 assembled into discrete trinuclear Ln3 (L1 /2 )3 and tetranuclear Ln4 (L1 /2 )4 macrocyclic structures under the basic condition. For these, there are multiple possible isomers coexisting in the solution which were enumerated and simulated with molecular mechanic modeling. Visible-light sensitized NIR emissions on the Yb complexes have been observed, endowing them potential application in photofunctional materials.