Structural diversity of a series of terpyridyl carboxylate coordination polymers: Luminescent sensor and magnetic properties

Highlights: • Eleven new coordination polymers and a closely zinc compound were constructed. • Their luminescence, magnetism and sensors were investigated. • Importantly, 12 shows highly efficient luminescent sensing for Fe³⁺ ion and NB. - Abstract: Eleven new coordination polymers, [Zn₂(ctpy)₂(HCOO)₂]_n·3nH₂O (1), [Zn₂(ctpy)₂(HCOO)₂(H₂O)₂]_n·nH₂O (2), [Zn₂(ctpy)₂(H₂O)₄]_n·2n(CH₃COO)·nH₂O (3), [Zn₂(ctpy)₂(CH₃COO)₂]_n·nH₂O (4), [Zn(ctpy)₂]_n·nH₂O (5), [Zn₂(ctpy)₂(Hidc)(H₂O)₂]_n (6), [Cd₂(ctpy)₄]_n (7), [Cd₂(ctpy)₂(Hidc)]_n (8), [Co₂(ctpy)₂(HCOO)₂(H₂O)₂]_n·nH₂O (9), [Co(ctpy)(DMF)(ox)_0.5]_n (10), [Co(ctpy)(ox)_0.5]_n (11) and the closely related compound [Zn(ctpy)(ox)_0.5]_n·0.5nH₂O (12) (Hctpy = 4′-carboxy-4,2′:6′,4′′-terpyridine, H₂ox = oxalic acid and H₃idc = imidazole-4,5-dicarboxylic acid) have been synthesized by hydro(solvo)thermal reaction of 4′-carboxy-4,2′:6′,4′′-terpyridine with divalent metal salts and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction. Compounds 1 and 4 have similar structure which demonstrate a two-fold interpenetrating 3D framework with a 3-connected utp topological net, which contains the same number of left and right-handed 2₁ helical chains. Compounds 2 and 9 are isostructural 2D layer with a 3-connected hcb topological net. Similar to 2, compound 3 also displays a 3-connected 2D hcb topological net. Compounds 5 and 10 are a 2D layer with a 4-connected sql topological net. Compound 6 shows a chiral 2D layer based on a 1D left- or right-handed helical chains, which are further extended into an achiral 2D + 2D→3D supramolecular network by hydrogen bonds with alternately arrangement. Compound 7 features an unusual 2-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,5)-connected binodal topological net with the Schläfli symbol of (5²·6)(5³·6³·7³·8). Compound 8 shows a 2D→3D supramolecular structure based on (3,4)-connected 2D bilayers with the Schläfli symbol of (4⁴·6²). Compound 11 displays an unusual three-dimensional coordination network which exhibits an intriguing (3,8)-connected binodal new topological net with Schläfli symbol (4²·6²)₂(4²·6²³·8³). Compound 12 features a two-fold interpenetrating (3,4)-connected 3D framework with the fsc topological net. Compounds 1–12 were obtained under similar reaction conditions. The diverse structures indicate that rational selection of the second ligand, metal salt, counter anion and solvent are good methods to further design metal-organic compounds with new structures and properties. Moreover, their thermal stabilities, photoluminescent and magnetic properties were also investigated. More importantly, compound 12 has been successfully applied in the detection of Fe³⁺ ion in DMF solutions and nitrobenzene and the possible detecting mechanism was also discussed.