CHROMOPHORIC WATER-SOLUBLE TETRAKIS(4-CARBOXYPHENYLAZO)-CALIX[4]ARENE- BINDING OF ARYLAMMONIUM IONS AND BENZENE

The interaction of water-soluble tetrakis(4-carboxyphenylazo)calix[4]a rene with N, N, N-trimethylarylammonium iodides and benzene was invest igated in order to correlate the effect of anilinium salts on the bind ing properties of the cup-shaped hydrophobic cavity with the monolayer spreading behavior of a series of amphiphilic analogs. Whereas multip le binding is observed for N, N, N-trimethylanilinium iodide and benze ne, NMR titration of tetrakis(4-carboxyphenylazo)calix[4]arene with N, N, N-trimethyl-N-(2-naphthyl)ammonium iodide indicates 2 : 1 complexa tion within the cavity of the calixarene with binding constants of K-1 = 8024 M-1 and K-2 = 3134 M-1.