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

Abstract

Abstract Six new diaza‐18‐crown‐6 ligands each containing two aromatic side arms with responsive functions were prepared. Diaza‐18‐crown‐6 containing two 4‐hydroxyazobenzene ( 3 ) or two 4 ‐hydroxy‐ 4′ ‐(dimethyl‐amino)azobenzene ( 4 ) substituents were prepared via a one‐pot Mannich reaction. Diaza‐18‐crown‐6 containing two benzimidazole ( 5 ), two uracil ( 6 ) or two 9,10‐anthraquinone ( 7 ) substituents were prepared by treating the diazacrown with the appropriate chloromethyl‐containing compound. Reductive amination using sodium triacetoxyborohydride, diaza‐18‐crown‐6 and ferrocenecarboxaldehyde was used to prepare bisferrocene‐substituted diaza‐18‐crown‐6 ( 8 ). Interactions of compounds 3 , 5 , and 6 with Na + , K + , Ba 2+ , Ag + , and Cu 2+ were evaluated by a calorimetric titration technique at 25° in methanol. All three ligands form more stable complexes with Ag + and Cu 2+ ( 5 forms a precipitate with Ag + ) than with Na + and K + . Ligand 5 also forms a highly stable complex with Ba 2+ .