Synthesis and characterization of 1,3,4-thiadiazole-2,5-dithio crown ethers
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Hetero-crown ethers (ligands I-IV) containing 1,3,4-thiadiazole-2,5-dithiol (bismuthiol) were synthesized and fully characterized. The ligands were prepared by a nucleophilic substitution (S(N)2) reaction of the appropriate ethylene glycol dihalide derivatives with 1,3,4-thiadiazole- 2,5-dithiol dipotassium salt under highly diluted conditions, and subsequent ring closure. Complexation constants and selectivity factors for these heterocyclic ligands in dichloromethane or chloroform were determined by ion-pair extraction from an aqueous solution containing Ag+, Ca2+, Zn2+, Fe3+, Cr3+, Co2+, Cd2+, Mg2+, Pb2+, Ni2+, Cu2+, Mn2+, Na+ and K+. These ligands could be applied as metal sensors and used to separate metals from various mixtures.