Theoretical investigations based principally on Monte Carlo calculations were conducted to interpret the hindered mobility of protons which was experimentally observed in a hybrid biological/artificial nanopore constituted of the ion bio-channel gramicidin A confined inside an artificial solid-state nanopore. We show that this experimental outcome may result from the high concentration of gramicidin A that progressively diminishes the transfer of proton from one side to the other of the nanopore. More, using molecular dynamic simulations data we demonstrate that the water molecules are repelling from the gramicidin structure outside the nanopore, leading to a strong decrease of the proton transfer.

Associations of organic and inorganic molecules involving non covalent and covalent interactions participate to a wide range of structures found in nature. Bridged silsesquioxanes (BS) can be designed with organic units selected to drive self-organization into a solid network. Therefore new hybrids functional materials with controlled morphologies can be synthesized. In particular urea groups, thanks to their ability to self-assemble though H bonds, have been incorporated in BS within the organic subunits (figure 1, UU). Depending on kinetics of the sol gel reaction, hybrid materials bridged by urea groups exhibiting a variety of textures and morphologies were synthetized. Considering the bridging group as a key element for the control of the assembly formed hybrids materials where thiourea groups have also been synthesized (Figure 1, UU or TT). As a matter of fact thiourea groups are also known to link them self via H bonds, but with geometry and strengths that can differ from urea links. Vibrational spectroscopy is used here to explore the self-organization mechanisms involved in the formation of urea bridged and thiourea bridged silsequioxanes. The influence of H-bonding strength and the self-organization properties of the urea and thiourea bridged organic substructures are explored through infra-red spectroscopy coupled with DFT calculations. Some particular vibrations such as amides and thio-amides vibrations are often considered as signatures of H bond strength. The thermal dependence dynamics of such signatures is studied as an indicator of the bond properties. Finally, in-situ high pressure vibrational measurements demonstrate the role of supramolecular interactions on the mechanical response of hybrid materials to high pressure.

Infrared response on a carbon nanotube is weak because this homonuclear allotrope of carbon does not bear permanent dipoles. Here, we report the discovery of an exaltation of the infrared absorption response in single-walled carbon nanotubes from dye molecule interactions. A study performed on dimethylquaterthiophene confined into the hollow core of single-walled carbon nanotubes or π-stacked at the outer surface of the latter leads to a symmetry breaking, allowing us to probe interactions between both subsystems. The nature of these interactions is discussed taking into account the tube diameter. This new phenomenon opens a new route to detect weak vibrations thanks to a confinement effect.

We report on the preparation of a hybrid nanomaterial made up of 1D filaments of an antiferromagnetic self-assembling bicopper complex encapsulated in polymer nanofibrils. The encapsulation process is achieved through the heterogeneous nucleation of the growth of polymer fibrils obtained by thermoreversible gelation as shown by calorimetry experiments. Neutron scattering experiments confirm that the filaments of a bicopper complex retain their 1D character after encapsulation in the fibrils. Superconducting quantum interference device experiments show that the bicopper complex, originally in the gapped spin state in the 3D bulk mesophase, displays a gapless behavior once encapsulated. Extended absorption fine structure and infrared results further highlight the difference in the molecular arrangement of the bicopper complex between the bulk mesophase and the encapsulated state, which may account for the magnetic behavior. This material, which is largely disordered, differs totally from the usual magnetic systems where this effect is observed only on highly crystalline systems with long-range order. Also, this hybrid material is very easy to prepare from its basic constituents and can be further processed in many ways.

NMR spectroscopy has been established as a potent method for the detn. of foldamer structures in soln. However, the NMR techniques could be limited by averaging, so addnl. exptl. techniques are often needed to fully endorse the folding properties of a sequence. The authors have recently demonstrated that oligo-​γ-​peptides composed of 4-​amino(methyl)​-​1,​3-​thiazole-​5-​carboxylic acids (ATCs) adopt an original helical fold stabilized by hydrogen bonds forming C9 pseudocycles. The main objective of the present work is to restudy the folding of ATC oligomer 1 to identify reliable FTIR and NMR structural markers that are of value for tracking the degree of organization of ATC-​based peptides.

The highly constrained b-amino acid ABOC induces different types of helices in b urea and 1:1 a/b amide oligomers. The latter can adopt 11/9- and 18/16-helical folds depending on the chain length in solution. Short peptides alternating proteinogenic a-amino acids and ABOC in a 2:1 a/b repeat pattern adopted an unprecedented and stable 12/14/14-helix. The structure was established through extensive NMR, molecular dynamics, and IR studies. While the 1:1 a-AA/ABOC helices diverged from the canonical a-helix, the helix formed by the 9-mer 2:1 a/b-peptide allowed the projection of the a-aminoacid side chains in a spatial arrangement according to the a-helix. Such a finding constitutes an important step toward the conception of functional tools that use the ABOC residue as a potent helix inducer for biological applications.