Compartmentalized host spaces accommodating guest aromatic molecules in a chiral way in a helix-peptide-aromatic framework.

A novel host molecular assembly of a free-standing flat nanosheet with compartmentalized spaces was prepared using a bolaamphiphilic peptide composed of two amphiphilic helical peptides and an oligo(naphthaleneethynylene) (ONE) unit at the center of the molecule. The nanosheet possesses void host spaces that can accommodate two mol-equivalent ONE groups to form columns of ONE groups in a right-handed helical way and ONE channels over a long distance. The present molecular system therefore can provide a chiral pore channel for relatively large molecules.

Joining Nanotubes Comprising Nucleobase-carrying Amphiphilic Polypeptides.

Three kinds of amphiphilic polypeptides, X-poly(sarcosine)-b-(L-Leu-Aib)6 (X = adenine, thymine, glycolic acid), were synthesized and self-assembled in a tris buffer to take on nanotube morphology. The nanotubes were joined together to extend the nanotube length with the addition of trifluoroethanol and heat treatment at 50 °C for 24 h. The length extension rate decreased in the order of adenine > glycolic acid > thymine depending on the N-terminal chromophores. Adenine-adenine interactions between the nanotubes were found to be more prevalent upon joining the nanotubes than adenine-thymine interactions. Further, adenines on the nanotube surface could chelate with Cu(ii) to thermodynamically stabilize the nanotube membrane. AFM imaging in liquid environment revealed that the membrane elasticity of the adenine nanotube was as high as ca. 1 MPa, which is considered to be strengthened as a result of the adenine-adenine interactions.