Syntheses, crystal structures and luminescent properties of four Zn(ii) coordination polymers with pyrazolone derivatives and 4,4′-bipyridine

Abstract

Four new Zn(II) coordination polymers, {[Zn(L₁)(4,4′-bipy)]·0.52CH₃OH}_n (1), {[Zn(L₂)(4,4′-bipy)]·CH₃OH}_n (2), {[Zn₃(L₃)₃(4,4′-bipy)_0.5]·3CH₃OH}_n (3), {[Zn(L₄)(4,4′-bipy)]·2CH₃OH}_n (4) (H₂L₁ = N-(1,3-diphenyl-4-propylene-5-pyrazolone) p-nitrobenzoylhydrazide, H₂L₂ = N-(1-phenyl-3-benzyl-4-propylene-5-pyrazolone) p-nitrobenzoylhydrazide, H₂L₃ = N-(1,3-diphenyl-4-propylene-5-pyrazolone) isoniazid, H₂L₄ = N-(1-phenyl-3-benzyl-4-propylene-5-pyrazolone) isoniazid, 4,4′-bipy = 4,4′-bipyridine) have been synthesized by the reactions of zinc acetate with the corresponding 4-acyl pyrazolone derivatives and 4,4′-bipyridine. The X-ray diffraction analyses revealed that complexes 1 and 2 exhibit 1D zigzag chain structures. The ligands (H₂L₁ and H₂L₂) serve as divalent tridentate chelating agents to coordinate with Zn(II) atoms. Complex 3 displays a complicated pillared-layer 3D framework and the ligands H₂L₃ adopt two different kinds of coordination modes. In the case of complex 4, the octahedral Zn(II) atoms are connected by the tetradentate ligands to form a 1D chain, then the 4,4′-bipyridine molecules further connect the 1D chains along the axial direction to generate a 2D network structure. The effect of the coordination groups and substituents at the 3-position of the ligands on the structure of the complexes have been discussed. Additionally, the luminescent properties of the complexes have been investigated in the solid state.