Synthesis of Proton-Ionizable p-Nitrophenol-Containing Tetraazacrown and Diazadithiacrown Ethers from an Aromatic Building Block Prepared via the Einhorn Reaction

A series of p -nitroanisole-containing tetraazacrown ( 14 − 18 ), diazacryptand ( 22 ), and diazadithiacrown ( 23 − 25 ) macrocycles has been prepared by treating the appropriate secondary diamine, diazacrown, or dimercaptan with 2,6-bis[(2-chloroacetamido)methyl]-4-nitroanisole ( BB ). Five of these p -nitroanisole-containing macrocycles were reported earlier. Four new bis( p -nitroanisole)-containing macrocycles resulting from a 2 + 2 macrocyclization of diamine or dimercaptan with BB were also isolated. Six of the p -nitroanisole-containing macrocycles ( 16, 17, 22 − 25 ) were converted to the p -nitrophenol-containing macrocycles ( 27 − 32 ) on treatment with LiI in refluxing pyridine. Thermodynamic quantities (log K, Δ H, and T Δ S ) for the interactions of four new compounds ( 24, 27, 31, and 32 ) with Na +, K +, Ba 2+, Ag +, and Pb 2+ were evaluated by calorimetric titration at 25.0 °C in either 70% or absolute methanol solution. The compounds show strong interactions with Ag + and Pb 2+ but very weak interactions with Na +, K +, and Ba 2+ . Ligand 31 exhibited high selectivity for Ag + over Pb 2+ . X-ray crystal structures were obtained for diazadithia macrocycle 23 and the Ag + − 31 complex.