COMPLEXATION PROPERTIES OF PREORGANIZED RECEPTOR MOLECULES FOR LARGE,NEUTRAL GUESTS

Receptor molecules with a preorganized cavity were synthesized by comb ining two resorcin[4]arene and one calix[4]arene building block. Based on predictions from a computational study which matches hosts and gue sts, several steroids, sugar derivatives, and alkaloids were selected for complexation studies. Experimentally the complexation of such gues ts by these receptor molecules was proven by H-1-NMR spectroscopy (ass ociation constants of 1.0-6.0 x 10(2) M-1 in CDCl3). One of these rece ptors with four hydroxyl groups forms a dimeric capsule (K-dimer = 11 M-1 in CDCl3). Evidence for this dimerization comes from H-1-NMR, FAB MS spectroscopy, and molecular mechanics and dynamics calculations.