Exploiting tapping mode-scanning force microscopy (TM-SFM), we characterized single polymeric chains of poly(isocyanodipeptides) (PICs) equilibrated in quasi two-dimensions on the basal plane of mica surfaces. While the average contour length 〈L〉 of an acid-catalyzed PIC bearing L-alanine-D-alanine methyl ester groups was as high as 5.3 µm, the corresponding Ni-catalyzed product exhibited an 〈L〉 of 70 nm. With a newly devised method based on the statistical analysis of the curvature of polymeric chains on a length scale up to about 100 nm from SFM images, we determined their persistence length lp. The measured value of lp ) 76 ( 6 nm for both products, independent of the contour length, indicates that the single polymer molecules are very rigid, i.e., even more rigid than the double-stranded DNA. This rigidity is attributed to the helical structure of the polymer backbone and, in particular, to the hydrogen-bonded networks that are present between the alanine moieties in the side chains.

All wrapped up: An easy, highly selective separation of C70 and the higher fullerenes has been achieved by solid–liquid extraction with a 2‐ureido‐4‐[1H]‐pyrimidinone‐based scaffold which wraps around the guest as a dimeric capsule (see picture), thereby solubilizing it in THF. Acidification disrupts the hydrogen‐bonding network and allows easy recovery of the guest and recycling of the receptor without chromatography or tedious procedures.

Connecting rods: Rigid rod–rod block copolymers are synthesized from peptide and polyisocyanide blocks (see picture: blue=poly(γ‐benzyl L‐glutamate); red=poly(methylbenzyl isocyanide) or poly(L‐isocyanoalanyl‐L‐alanine methyl ester). The polyisocyanide helix has side arms organized in a parallel β‐sheet (light blue). Some copolymers self‐assemble into ordered layers of hollow capsules.

Isolated slightly hydrophilic chains of poly(isocyanodipeptides) (PICs) adsorbed on mica were studied by intermittent contact mode-scanning force microscopy (IC-SFM) in an ambient atmosphere controlled both with respect to the relative humidity (RH) and the presence of CHCl 3 vapor. SFM revealed that the average chain height increases up to more than an order of magnitude with decreasing RH, leading to the highest value at RH ) 0%. This is due to both a minimization of the capillary forces between the SFM tip and the hydrophilic substrate surface and a collapse of the side chains in the poor solvent. In a saturated CHCl 3 vapor atmosphere, the chain heights increase up to twice this value, which is close to the polymer diameter measured by powder X-ray diffraction. This indicates that the PIC chains are solvated by CHCl 3 molecules, causing the swelling of the single polymers. Achieving a control over the thickness of the polymer chains is fundamental for their optimal observation by SFM. Moreover, the understanding of the conformational properties of single macromolecules adsorbed on surfaces under different environmental conditions is of importance for unraveling their physicochemical properties and their dynamics, including their reactivity.