Hydrothermal synthesis, structures, and luminescent properties of four new zinc(ii) diphosphonate hybrids with mixed ligands

Abstract

By introduction of 2,2′-bipy or 1,10-phen as a second organic ligand, four new zinc(II) diphosphonate hybrids with mixed ligands, namely, [Zn(2,2′-bipy)(hedpH₂)]·0.5H₂O (1), [Zn(1,10-phen)(hedpH₂)]·H₂O (2), [Zn₂(1,10-phen)(hedpH₂)₂]·H₂O (3) and [Zn(1,10-phen)(hedpH₂)] (4) (hedpH₄ = 1-hydroxyethylidenediphosphonate, 2,2^′-bipy = 2,2′-bipyridine, 1,10-phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions. Compounds 1 and 2 adopt a two-dimensional supramolecular network structure containing {[Zn(2,2′-bipy)(hedpH₂)]₂} or {[Zn(1,10-phen)(hedpH₂)]₂} units. The neighboring units interdigitate through hydrogen bonding interactions to give a 2D supramolecular network. Compounds 3 and 4 also have a two-dimensional supramolecular network structure. In compounds 3 and 4, 1D Zn–diphosphonate chains were formed. These 1D chains are further connected to adjacent chains through hydrogen bonds to form a 2D supramolecular network. A notable feature for compound 4 is the presence of the alternate left- and right-handed helical chains in the structure. The luminescence properties of compounds 1–4 have also been studied.