There is growing interest in the design of molecules that undergo predictable self-assembly. Such systems offer the prospect of tuning the properties of materials based on precise tailoring of molecular structure. Progress in this field is driven both by fundamental scientific curiosity and by the numerous potential applications that can be envisioned for "smart" materials. Peptides are attractive as building blocks for self-assembling materials because it is easy to incorporate a wide array of functionality onto the side chain of these molecules because peptides tend to be biocompatible, and the rules that govern peptide self-association are moderately well understood. [1] Bioinspired oligomers with well-defined conformational propensities, called "foldamers", [2] have comparable advantages for materials applications, [3] and they resist proteolytic degradation. [4] Herein we describe designed amphiphilic oligomers that contain both a-amino acid and b-amino acid residues, which are called "a/b-peptides". These amphiphilic oligomers are intended to assemble through the formation of hydrogen-bonded sheets at the air-water interface.
The two a/b-peptides we examined, bKbE and bEbK, differ in the positions of the ionizable side chains, which are provided by b 3 -homolysine (b 3 hLys) and b 3 -homoglutamic acid (b 3 hGlu) residues, and both contain 11 residues with 1:1 alternation of a and b subunits along the backbone.