Improved selectivity for Pb(ii) by sulfur, selenium and tellurium analogues of 1,8-anthraquinone-18-crown-5: synthesis, spectroscopy, X-ray crystallography and computational studiesElectronic supplementary information (ESI) available: Crystallographic characterization data, NMR, MS, and tables of atom coordinates with absolute energy, cyclic voltammetry, and spectroscopic data are available for free of charge. CCDC 980449-980454. For ESI and crystallographic data in CIF or other electronic forma

We report here a series of heteroatom-substituted macrocycles containing an anthraquinone moiety as a fluorescent signaling unit and a cyclic polyheteroether chain as the receptor. Sulfur, selenium, and tellurium derivatives of 1,8-anthraquinone-18-crown-5 ( 1 ) were synthesized by reacting sodium sulfide (Na 2 S), sodium selenide (Na 2 Se) and sodium telluride (Na 2 Te) with 1,8-bis(2-bromoethylethyleneoxy)anthracene-9,10-dione in a 1 : 1 ratio. The optical properties of the new compounds are examined and the sulfur and selenium analogues produce an intense green emission enhancement upon association with Pb( ii ) in acetonitrile. Selectivity for Pb( ii ) is markedly improved as compared to the oxygen analogue 1 which was also competitive for Ca( ii ) ion. UV-Visible and luminescence titrations reveal that 2 and 3 form 1 : 1 complexes with Pb( ii ), confirmed by single-crystal X-ray studies where Pb( ii ) is complexed within the macrocycle through coordinate covalent bonds to neighboring carbonyl, ether and heteroether donor atoms. Cyclic voltammetry of 2-8 showed classical, irreversible oxidation potentials for sulfur, selenium and tellurium heteroethers in addition to two one-electron reductions for the anthraquinone carbonyl groups. DFT calculations were also conducted on 1 , 2 , 3 , 6 , 6 + Pb( ii ) and 6 + Mg( ii ) to determine the trend in energies of the HOMO and the LUMO levels along the series. Selectivity for toxic Pb( ii ) ion is improved by changing donor heteroatoms in the host.