Design, synthesis and transporting mechanism of hydrophilic artificial water channels

Water plays a crucial role in all living cells and organisms, and efficient regulation of transmembrane water dynamic homeostasis is essential for most biological processes. Aquaporins, as naturally occurring proteins, are able to facilitate the transport of water across cell membranes with high permeability and exceptional selectivity. However, the structural complexity and poor stability of aquaporins in artificial media other than cellular membranes have prompted researchers to mimic aquaporins and develop artificial water channels combining high permeability and selectivity with chemical stability. In this thesis, we have designed and synthesized a series of small amphiphilic molecules with specific structures used to construct artificial water channels with hydrophilic cavities, urea scaffolding backbone and hydrophobic lateral chains in interaction with external membranes. Moreover, we focused on the water transport performances of artificial water channels in bilayer and polymeric membrane environments, and mainly obtained three parts of research results. This thesis hopes to tackle the above issues through developing new synthetic water channel to leverage their versatility, rich chemistry, tunable structures, and solution-processability.In Chapter I, we start with the historical development and significant advancements of current reported artificial water channels, and attempt to reveal important structural insights and supramolecular self-assembly principles governing the selective water transport mechanisms, toward innovative AWC-based biomimetic membranes for desalination. Furthermore, in Chapter II, we report octyl-ureido-polyols capable of self-assembly into hydrophilic hydroxy channels which adaptively transport water molecules or clusters depending on their concentration in lipid membranes. Afterwards, to get deeper insight into the differences of water-wires/water-clusters permeation approaches, we bring forward U-shaped diimidazole water channels constructed from pyridine bis(formamide-ethyl-imidazole) derivatives in which single-crystal structures reveal the two distinct transport behaviors of water, in Chapter III. In the final chapter, we investigate the structural determinants affecting the performance of I-quartet water channels in bilayer or polymeric membranes, and develop new concepts for desalination through bio-assisted AWC-membranes.This Ph.D. project introduces new synthetic water channels, and elaborate on the structure-performance analysis that can be used to rationalize artificial water channels design toward the fabrication highly permselective membranes for desalination.