Cation–pi interactions in neutral calix[4]resorcinarenes

✍ Scribed by Jerry L Atwood; Agnieszka Szumna

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 290 KB
• Volume: 2
• Category: Article
• ISSN: 1472-7862
• DOI: 10.1016/s1472-7862(03)00068-6

✦ Synopsis

The interaction of the neutral form of resorcin [4]arene 1 (R=i-Bu) with tetraalkylammonium cations (Me 4 N + , Et 4 N + , Pr 4 N + and Bu 4 N + ) was analyzed in the solid state and in methanol solutions. In methanol, NMR titration results indicate almost no differentiation between Me 4 N + and Et 4 N + cations (K ass (Me 4 N + )=93 M À1 and K ass (Et 4 N + )=81 M À1 ) and a relatively low association constant for Pr 4 N + ( K ass (Pr 4 N + )=25 M À1 ). In the solid state, for the Me 4 NCl complex, the resorcinarene assumes the C 2v boat conformation and is surrounded by as many as four Me 4 NCl moieties. The structure of the Et 4 NCl complex indicates that ethyl group can be conveniently placed in the resocin[4]arene cavity. The larger Bu 4 N + cation was found completely external to the cavity.