Four coordination polymers based on 1,4,8,11-tetrazacyclotetradecane-N,N′,N″,N‴-tetra-methylene-benzoic acid: Syntheses, structures, and selective luminescence sensing of iron(III) ions, dichromate anions, and nitrobenzene

• The luminescence intensities of 1–3 exist significant quenching effects when loaded Fe3+ ions.
• Detecting Cr2O72− anion of 1 is much more sensitive than those of 2 and 3.
• 1–3 could be applied as fluorescence sensors for nitrobenzene with high sensitivity and high selectivity.

Four two dimensional coordination polymers, {[Zn2(L)(biim-4)]·2H2O}n (1), {[Zn2(L)(biim-4)]·2H2O}n (2), [Cd2(L)(biim-4)(DMF)2]n (3) and {[Co2(L)(biim-4)]·3H2O}n (4), where H4L = 1,4,8,11-tetrazacyclotetradecane-N,N′,N″,N‴-tetra-methylene-benzoic acid and biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), have been synthesized under solvothermal conditions. In the structures, L anions and biim-4 ligands unite their respective metal ions to furnish layer with binuclear units. The layers are further connected by C–H···π interactions into three dimensional supramolecular architectures, respectively. The compounds were characterized by Infrared spectrum and powder x-ray diffraction patterns. The luminescent recognition properties of polymers 1–3 to metal cations, anions and small organic molecules have also been explored systematically. The results demonstrate that 1–3 display high sensitive and selective luminescent sensing towards Fe3+ ion, Cr2O72− anion and nitrobenzene. The variable-temperature magnetic susceptibility of coordination polymer 4 was also investigated.

Four coordination polymers based on 1,4,8,11-tetrazacyclotetradecane-N,N′,N″,N‴-tetra-methylene-benzoic acid have been successfully synthesized. The luminescent sensing of Fe3+ ion, Cr2O72− anion, and nitrobenzene for polymers 1–3 have been explored systematically.Figure optionsDownload as PowerPoint slide