Structure and dynamics of nanoconfined water and aqueous solutions

Abstract

This review is devoted to discussing recent progress on the structure, thermodynamic, reactivity, and dynamics of water and aqueous systems confined within different types of nanopores, synthetic and biological. Currently, this is a branch of water science that has attracted enormous attention of researchers from different fields interested to extend the understanding of the anomalous properties of bulk water to the nanoscopic domain. From a fundamental perspective, the interactions of water and solutes with a confining surface dramatically modify the liquid's structure and, consequently, both its thermodynamical and dynamical behaviors, breaking the validity of the classical thermodynamic and phenomenological description of the transport properties of aqueous systems. Additionally, man-made nanopores and porous materials have emerged as promising solutions to challenging problems such as water purification, biosensing, nanofluidic logic and gating, and energy storage and conversion, while aquaporin, ion channels, and nuclear pore complex nanopores regulate many biological functions such as the conduction of water, the generation of action potentials, and the storage of genetic material. In this work, the more recent experimental and molecular simulations advances in this exciting and rapidly evolving field will be reported and critically discussed.

Using Car-Parrinello simulations and microscopic order descriptors to reveal two locally favored structures with distinct molecular dipole moments and dynamics in ambient liquid water

“…The complex behavior of water has motivated the scientific community to develop novel theories and methodologies to provide deeper insight into the molecular causes of its anomalies compared to most liquids [1][2][3][4][5][6][7][8][9][10][11] . A molecular understanding of the water properties is crucial in numerous processes in chemistry, physics, geosciences, biology, and life evolution 3,4,9,10,[12][13][14][15][16][17] .…”

Pushing the limits of nanopore transport performance by polymer functionalization

“…For very small pores (o1-2 nm) such as graphene nanopores, no bulk behavior for water is observed anymore and high transport rates have been reported especially in the case of hydrophobic nanopores of this size. [97][98][99][100][101][102][103][104] This increase in water transport rates is known in biological pores like aquaporin. 10 Furthermore, an interesting phenomenon of hydrophobic nanoscale pores is hydrophobic gating due to water evaporation.…”

Membraneless physiology of the living cell. The past and the present

“…In a living cell and in phase models of the cell, in coacervates and in Fox's proteinoid microspheres [16], the moderators of water properties are macromolecules and, above among these, proteins, as the most numerous type of polymers. Physicists are well aware that water dramatically changes its structure when interacting with the surface, even if it is not charged [17], but there are always charged functional groups on the molecular surface of proteins, they are represented at least by alternating dipole functional groups of peptide bonds (see below). These changes lead to the restructuring of the network of hydrogen bonds between water molecules and, as a consequence, to the emergence of a new aqueous phase bordering on bulk water (both phases are dynamic, but the differences in dynamics have a functional significance).…”

“…Changing the structure of water under the influence of any surface with which it interacts is a fundamental physical phenomenon [17]. Cytologists came to the phenomenological conclusion that intracellular water differs in its properties from bulk water almost 200 years ago, but, even more surprisingly, they believed that the altered state of water in the cell allows it to be considered as a membraneless compartment [4].…”