Complexation of metal ions with the novel diazadithia crown ethers carrying two pyrene pendants in acetonitrile-tetrahydrofuran

Two crown ethers carrying pyrene side arms with nitrogen-sulfur donor atom were designed and synthesized by the reaction of the corresponding macrocyclic compounds and 1-bromomethyl-pyrene. The influence of metal cations such as Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ on the spectroscopic properties of the ligands was investigated in acetonitrile-tetrahydrofuran (1:1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Al3+, Zn2+, Fe2+, Ni2+, Cu2+, and Pb2+ with 16-membered crown ether. Similar results were obtained for Al3+, Fe2+, Hg2+, Cu2+ and Pb2+ with 14-membered crown ether. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constants of the novel ligands with these cations. According to spectrofluorimetric titration measurements the 14-membered diazadithia crown ether showed sensitivity for Pb2+ with linear range and detection limit of 1.3 × 10-6 to 5.2 × 10-5 M and 5.2 × 10-7 M, respectively. The 16-membered diazadithia crown ether showed sensitivity for Ni2+ with linear range and detection limit of 1.3 × 10-7 to 5.2 × 10-6 M and 4.1 × 10-8 M, respectively.