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 H4L1 and H4L2. 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 H4L1 was assembled into dinuclear double-strand helicate Ln(2)(H2L1)(2) by partially-deprotonated assembly with La, Sm or Eu, while trinuclear Ln(3)(H2L1)(3) with Yb or Lu. For linear H4L2, infinite 1D zig-zag metal-organic polymeric chain (Ln(2)H(2)L(2))(n) was obtained. However, complete deprotonated L-1 and L-2 assembled into discrete trinuclear Ln(3)(L-1(/2))(3) and tetranuclear Ln(4)(L-1(/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.