The molecular alignment of an alkylthiophene, 3-n-octadecylthiophene, on highly oriented pyrolytic graphite has been studied by scanning tunneling microscopy (STM). Lateral stripes with a period of 0.42 nm and vertical stripes with one of 5.0 nm are observed and assigned to molecular alignments of alkyl chains and thiophene rings connected by “head to head", respectively. An STM image of N-n-octadecylpyrrole is also presented.

Oligo(Leu)s containing Pro or (Dmob) Leu residues were prepared by the stepwise elongation and fragment condensation methods. The peptides prepared were the following: Boc‐Leun‐OBzl (n = 3–6 and 9), Boc‐Pro‐Leu3‐OBzl, Boc‐Leun‐Pro‐OBzl (n = 3–5), Boc‐Leun‐Pro‐Leu3‐OBzl (n = 3 and 4), Boc‐(Leu4‐Pro)2‐OBzl, Boc‐Leu3‐Pro‐Leun‐Pro‐Leu3‐OBzl (n = 6 and 7), Boc‐Leu3‐Gly‐(Dmob) Leu‐OMe, Boc‐[Leu3‐Gly‐(Dmob) Leu‐Leu3]n‐OBzl (n = 1 and 2). The insertion of the Pro and Gly‐(Dmob) Leu residues into a peptide chain caused “the peptide segment separation” and achieved remarkable solubility improvement of N‐ and C‐protected oligo(Leu) derivatives in a variety of organic solvents. The conformations of typical peptides in the solid state and in DMSO were also investigated using i.r. spectroscopy. The incorporation of tertiary peptide bonds in a central position of the β‐sheet structure induces the onset of an unordered structure in the solid state. In DMSO, peptides are efficiently subjected to solvation to have the unordered structure.

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