In situ synthesis and structural characterization of a series of acylhydrazidate-extended Ln3+ and Zn2+ coordination polymers

Abstract

By utilizing the in situ hydrothermal acylation of N₂H₄ with aromatic polycarboxylic acids, a series of new acylhydrazidate-extended two-dimensional (2-D) or three-dimensional (3-D) coordination polymers, [Ln(epdh)₃(H₂O)] (Ln³⁺ = Dy³⁺1, Eu³⁺2, Tb³⁺3, Gd³⁺4, Y³⁺5, Lu³⁺6; epdh = 5-ethylpyridine-2,3-dicarboxylhydrazidate), [Dy(ox)(pdh)(H₂O)] (ox = oxalate, pdh = pyridine-2,3-dicarboxylhydrazidate) 7, [Zn₂(mpth)(atez)₂] (mpth = 4-methylphthalhydrazidate, atez = 5-aminotetrazolate) 8 and [Zn₃(OH)₂(Hpth)₂(atrz)₂] (pth = phthalhydrazidate, atrz = 3-amino-1,2,4-triazolate) 9 were isolated. X-ray single-crystal diffraction revealed that (i) the isomorphic compounds 1–6 posses 2-D layer structures with (4,4) topologies. Two types of epdh molecules act as the rod-like connectors; (ii) compound 7 also possesses a 2-D layer structure, but shows a (6,3) topology. The pdh molecules first link the Dy³⁺ ions into a dimer. The ox molecules further extend the dimers into this 2-D layer network; (iii) compound 8 has a 3-D network structure (symbol: (4·6⁴·8)₂(4²·6²·8²)), which is constructed from the one-dimensional (1-D) Zn₂(mpth)²⁺ chains by the atez molecules; (iv) the 2-D layer network of compound 9 also shows a (6,3) topology, but the geometrical form is different from that of compound 7. Only the atrz molecule serves as the linker in compound 9; (v) via the N–H⋯O and/or N–H⋯N interactions, compounds 1–6, 7 and 9 self-assemble into the different 3-D supramolecular networks. Photoluminescence analysis revealed that (i) compounds 2 and 3 exhibit the characteristic transitions of the Eu³⁺ or Tb³⁺ ion; (ii) compounds 1, 4, 5 and 6 emit green light, suggesting their behaviors are dominated by the epdh molecules; (iii) compound 8 emits violet light, whereas compound 9 does not emit light.