Diaza-18-crown-6 ligands containing two aminophenol sidle arms: New heterobinuclear metal ion receptors

Three diaza-18-crown-6 ligands substituted with two aminophenol side arms w ere synthesized as possible heterobinuclear metal ion receptors. Bis(p-amin ophenol)-substituted diaza-18-crown-6 ligand (13) was prepared by treating the diazacrown with alpha-bromo-4-nitro-o-cresol in the presence of N,N-dii sopropylethylamine followed by reduction of the nitro groups. Bis(o-aminoph enol)substituted diaza-18-crown-6 ligands (11 and 12) were prepared in two steps by the aminomethylation of either an o-nitrophenol or o-(trifluoroace tamido)phenol followed by reduction of the nitro groups or hydrolysis of th e trifluoroacetamide groups. All new bisphenol-armed diazacrown ligands wer e purified by ultrasonication in MeOH followed by filtration and drying. In teraction of the ligands with Na+, K+, Ag+, and Cu2+ was evaluated by a cal orimetric titration technique at 25 degrees C in MeOH. The complexes of Ag and Cu2+ much more stable than those of Na+ and K+. Heterobinuclear comple xes were observed for 11-Cu2+- Na+ and 12-Cu2+-Na+ but not for 13-Cu2+-Naor for 12-Cu2+-Ag+.