Folding processes play a crucial role in the development of function in biomacromolecules. Recreating this feature on synthetic systems would not only allow understanding and reproducing biological functions but also developing new functions. This has inspired the development of conformationally ordered synthetic oligomers known as foldamers. Herein, a new family of foldamers, consisting of an increasing number of anthracene units that adopt a folded sigmoidal conformation by a combination of intramolecular hydrogen bonds and aromatic interactions, is reported. Such folding process opens up an efficient through-space charge transport channel across the interacting anthracene moieties. In fact, single-molecule conductance measurements carried out on this series of foldamers, using the scanning tunnelling microscopy-based break-junction technique, reveal exceptionally high conductance values in the order of 10−1 G0 and a low length decay constant of 0.02 Å−1 that exceed the values observed in molecular junctions that make use of through-space charge transport pathways.

The tumor-associated carbohydrate Tn antigens include two variants, αGalNAc- O-Thr and αGalNAc- O-Ser. In solution, they exhibit dissimilar shapes and dynamics and bind differently to the same protein receptor. Here, we demonstrate experimentally and theoretically that their conformational preferences in the gas phase are highly similar, revealing the essential role of water. We propose that water molecules prompt the rotation around the glycosidic linkage in the threonine derivative, shielding its hydrophobic methyl group and allowing an optimal solvation of the polar region of the antigen. The unusual arrangement of αGalNAc- O-Thr features a water molecule bound into a "pocket" between the sugar and the threonine. This mechanism is supported by trapping, for the first time, such localized water in the crystal structures of an antibody bound to two glycopeptides that comprise fluorinated Tn antigens in their structure. According to several reported X-ray structures, installing oxygenated amino acids in specific regions of the receptor capable of displacing the bridging water molecule to the bulk-solvent may facilitate the molecular recognition of the Tn antigen with threonine. Overall, our data also explain how water fine-tunes the 3D structure features of similar molecules, which in turn are behind their distinct biological activities.

Sugars are fundamental building blocks for living organisms and their interaction with proteins plays a central role in fundamental biological processes, such as energy storage and production, post-transductional modifications or immune response. Understanding those processes require deep knowledge of the forces that drive the interactions at the molecular level. Here we explore the interactions between α/β-methyl-d-glucopyranose and β-phenyl-d-glucopyranose with phenol, and the chromophore of tyrosine, using a combination of mass-resolved laser electronic spectroscopy in supersonic expansions and quantum mechanical calculations. The structures of the complexes detected in the jet are stabilized by a subtle equilibrium between several types of weak interactions, among which the dispersion forces may tilt the balance. In particular, the small structural changes introduced by the orientation of the anomeric substituent are amplified by the interaction with phenol. Consequently, the number of conformational isomers detected experimentally is different for each system and they present also differences in the preferred solvation site. Furthermore, inclusion of entropic terms for the calculated structures is advisable to understand the energetic reasons for the detection of a small set of experimental conformational isomers.

When hydrogen is completely replaced by fluorine, arenes become prone to form a lone pair···π-hole non-covalent bond with ligands presenting electron rich regions. Such a species is ammonia, which confirms...

Rotational spectroscopy and isotopic studies evidence oxygen exchange in water complexes of atmospherically important acrolein.