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Understanding the determinants of permeability and selectivity in biological channels serves two general purposes. It provides fundamental biophysical insights and allows the evaluation of new membrane proteins and artificial channel designs for the development of biomimetic separation membranes. This understanding relies on accurate ways to quantify unitary (single channel) solute and solvent permeabilities. However, the current research in biomimetic and bioinspired membranes and in protein biophysics tends to focus on relative permeabilities. Further, many methods and approximations currently used result in erroneous permeability values which hinder and complicate the comparison between channels. Combined, these gaps in the available measurements obscure the biophysical insights and impede the development of novel high-performance channels. In this review, we summarize in vitro model membrane systems useful to functionally characterize artificial as well as biological channels. We also critically discuss biophysical techniques capable of extracting permeability values and membrane channel densities, which are fundamental parameters required to determine accurate unitary permeability values. Pertinent examples are provided, along with advantages, disadvantages, and potential improvements needed for specific techniques to acquire accurate unitary permeability values for a diverse set of small molecules, including water, ions, weak acids and bases, neutral molecules, and protons. Version of record

Foldamer chemistry is a rapidly developing research area where scientists study the construction of various artificial architectures that inspired from the folded conformations of biopolyme rs found in nature. This thesis focuses on the design and construction of complex molecular topologies and switchable molecular motions. In the first part, with the helical disruptor strategy, variable sizes of macrocycles were built up (from 4 units to 12 units) based on quinolinecarboxamides derivatives (Q F ). Macrocycles adopted novel conformations which were totally different with the helical conformations of their own foldamer precursors. Those novel structures were confirmed by NMR and crystallographic studies. In the second part, a symmetrical helix sheet helix foldamer was prepared which has a bind with T shape rod. The photoreactions within aromatic sheets change the architectures of foldamer that cause dissociation of complex and release the rod. A thermal treatment would recover foldamer back to initial conformation and lead to the re formation of host guest complex. I n the third part, to build up the molecular Prusik knot, different turn units were incorporated with helix segments to form helix tur n helix foldamers. The conformations of helix turn helix architectures were well investigated, they adopted several kinds of conformations, such as cone shape, multiple helix and precursor of Prusik knot., La chimie des foldamères est un domaine de recherche en développement rapide où les scientifiques étudient la construction de diverses architectures artificielles inspirées des conformations repliées des biopolymères. Cette thèse porte sur la conception et la construction de topologies moléculaires complexes et de mouvements moléculaires commutables. Dans la pr emière partie, avec la stratégie du disrupteur hélicoïdal, des macrocycles de tailles variables ont été construits (de 4 unités à 12 unités) à base de dérivés de quinoléinecarboxamides (Q F ). Les macrocycles formés adoptent de nouvelles conformations totale ment différentes des conformations hélicoïdales de leurs précurseurs respectifs. Ces nouvelles structures ont été confirmées par RMN et études cristallographiques. Dans la deuxième partie, un foldamère hélice feuillet hélice symétrique, capable d’accueilli r une molécule invitée en forme de T, a été préparé. L’irradiation lumineuse des feuillets aromatiques modifient l’architecture du foldamère ce qui provoquent la dissociation du complexe et libèrent la molécule en forme de T. Un traitement thermique permet la reformation du complexe hôte invité. Dans la troisième partie de cette thèse, la conception d’un noeud Prusik moléculaire, basée sur un foldamère de type hélice feuillet hélice, est discutée. Les conformations des architectures hélice feuillet hélice, t elles que la forme conique, l'hélice multiple et le précurseur du noeud Prusik, ont été étudiées.