Syntheses of diaza-18-crown-6 ligands containing two units each of 4-hydroxyazobenzene, benzimidazole, uracil, anthraquinone, or ferrocene groups

Six new diaza-18-crown-6 ligands each containing two aromatic side arms wit h responsive functions were prepared. Diaza-18-crown-6 containing two 4-hyd roxyazobenzene (3) or two 4-hydroxy-4'-(dimethylamino)azobenzene (4) substi tuents were prepared via a one-pot Mannich reaction. Diaza-18-crown-6 conta ining two benzimidazole (5), two uracil (6) or two 9,10-anthraquinone (7) s ubstituents were prepared by treating the diazacrown with the appropriate c hloromethyl-containing compound. Reductive amination using sodium triacetox yborohydride, diaza-18-crown-6 and ferrocenecarboxaldehyde was used to prep are bisferrocene-substituted diaza-18-crown-6 (8). Interactions of compound s 3, 5, and 6 with Na+, K+, Ba2+ Ag+, and Cu2+ were evaluated by a calorime tric titration technique at 25 degrees in methanol. All three ligands form more stable complexes with Ag+ and Cu2+ (5 forms a precipitate with Ag+) th an with Nat and K+. Ligand 5 also forms a highly stable complex with Ba2+.