Heterocalixarenes. Part 2. Calix[m]uracil[n]benzimidazol-2(1H)-one[3] arenes: Synthesis and Binding Characteristics

The reactions of uracil/benzimidazol-2(1H)-one with 1,3-bis(bromomethyl)benzene provide respectively1 3-bis(3-bromomethylbenzene)methyl]uracil/benzimidazol-2(1H)-onewhich on subsequent cyclization with1,3-bis(uracil-1-yl/benzimidazol-2(1H)-one-1-yl)methyl]benzenederivatives provide respectively calixm]uraciln]benzimidazoI-2(1H)-one3]arenesm =3, n = 0 (9); m = 2, n = 1 (10);m = 1, n = 2 (11) and m = 0, n = 3 (12)]. The heterocalixarenes 9–12, both in liquid–liquid and solid–liquid extraction experiments, selectively extract ammonium picrates over the similarly sized K⁺ picrate. The selectivity is much more pronounced in the case of solid-liquid extractions. Both in L-L and S-L extractions, 10 exhibits the highest order oft-BuNH₃ ⁺/K⁺ selectivity.