A concept for the rational design of sequence-selective peptide receptors has been extended: in addn. to recognition modules for polar, arom. and basic amino acids, the series has now been completed with new receptor units for apolar and acidic amino acids. The underlying strategy uses the intermol. b-sheet stabilization of a dipeptide as a prerequisite to bind its N-terminal amino acid side chain through a strategically placed recognition tip at the end of a U-turn protruding from the receptor moiety. Thus, a diaminopyrazole has been covalently attached to Kemp's triacid by way of a cyclic imide, while a meta-substituted aniline was coupled as an amide to the pendant third carboxylate arm, bringing the two arom. units into a sub-van der Waals distance in a tight conformational lock. NMR titrns., Karplus analyses and Monte-Carlo simulations demonstrate the effective sequence-selective recognition of alanine-contg. dipeptides. No example of such a rationally designed set of peptide receptors had existed previously.