Structure Of Water Clusters Research Articles

Spectroscopic and Theoretical Identifications of Two Structural Motifs of (H2O)10 Cluster.

Precise characterization of archetypal systems of aqueous hydrogen-bonding networks is essential for developing accurate potential functions and universal models of water. The structures of water clusters (H2O)n (n = 2-9) have been verified recently through size-specific infrared spectroscopy with a vacuum ultraviolet free electron laser (VUV-FEL) and quantum chemical studies. For (H2O)10, the pentagonal prism and butterfly motifs were proposed to be important building blocks and were observed in previous experiments. Here we report the size-specific infrared spectra of (H2O)10 via a joint experimental and theoretical study. Well-resolved spectra provide a unique signature for the coexistence of pentagonal prism and butterfly motifs. These (H2O)10 motifs develop from the dominant structures of (H2O)n (n = 8, 9) clusters. This work provides an intriguing prelude to the diverse structure of liquid water and opens avenues for size-dependent measurement of larger systems to understand the stepwise formation mechanism of hydrogen-bonding networks.

Real-time detection of the transport of water cluster across cytomembrane with piezoelectric sensor

Acquiring insight into the transport of water clusters across cytomembrane is vital and essential for elucidating cell functions and water channels. Herein, A highly sensitive living cell analysis platform was developed for monitoring the transport dynamics of water clusters through water channels by combining the piezoelectric transducer and the hypotonicity-caused cell volume regulation. The various drinking water was used as the hypotonic perfusate to stimulate vascular endothelial cells and the temporal frequency response to cells was obtained to analyze the transport rate of the influx and efflux of water clusters which is related to water structure. The sensor is capable to distinguish the transport dynamics of different water clusters in five drinking water which the transport rates of water influx of cells are 5.1 ± 0.40, 6.6 ± 0.96, 7.4 ± 0.46, 8.1 ± 0.86, and 8.4 ± 0.80 Hz min−1 (n = 3), respectively, showed that they are ranked in the increasing order: M-water, C-water, S-water, RO-water, d-water. Moreover, inhibitor of HgCl2 was used to block water channels to reveal the water transport via water channels. Conductivity and infrared spectroscopy assays further confirmed the differences of transport dynamics between these drinking water due to the structure or size of water clusters caused by the mineral substance or the electromagnetic field. Therefore, this work provides a novel, simple and effective method for monitoring the transport of different water cluster across cytomembrane.

Modeling Ultrafast Transport of Water Clusters in Carbon Nanotubes.

Carbon nanotubes can be used as ultrafast liquid transporters for water purification and drug delivery applications. In this study, we mathematically model the interaction between water clusters and carbon nanotubes using a continuum approach with the Lennard-Jones potential. Since the structure of water clusters depends on the confining material, this paper models the cluster as a cylindrical column of water molecules located inside a carbon nanotube. By assuming the system of two concentric cylinders, we derive analytical expressions for the interaction energy and force, which are used to determine the mechanics and physical parameters that optimize water transport in the nanotubes. Additionally, we adopt Verlet algorithm to investigate the ultrahigh-speed dynamics of water clusters inside carbon nanotubes. For a given carbon nanotube, we find that the cluster's length and the surface's wettability are important factors in controlling the dynamics of water transport. Our findings here demonstrate the possibility of using carbon nanotubes as effective nanopumps in water purification and nanomedical devices.

Water clusters in liquid organic matrices of different polarity

The cluster structure of water is continuously a subject of intense scientific discussion. Because of the electronic and structural characteristics, the experimental studies still present a great challenge. In this work, the water clusters formed in organic liquid matrices of different polarities are studied. Various chlorine hydrocarbons differing in dipole moment were used as dispersing media, namely: carbon tetrachloride, chloroform, dichloromethane and 1,2-dichloroethane. Simple infrared absorption spectroscopy combined with Molecular Dynamics simulations and Density Functional Theory calculations were found to be a very effective tool for the precise determination of the water cluster structure. For the first time, the correlation between experiments and computations is presented at this level of accuracy. The main results show that a higher polarity of the organic matrix favours the formation of stable, small, and cyclic water clusters, while in the nonpolar matrix water molecules tend directly to phase separation on the macroscopic scale. Moreover, the size of the clusters formed by water molecules strongly depends on the water content in the matrix.

Rotational dive into the water clusters on a simple sugar substrate

Most biomolecular activity takes place in aqueous environments, and it is strongly influenced by the surrounding water molecules. The hydrogen bond networks that these water molecules form are likewise influenced by their interactions with the solutes, and thus, it is crucial to understand this reciprocal process. Glycoaldehyde (Gly), often considered the smallest sugar, represents a good template to explore the steps of solvation and determine how the organic molecule shapes the structure and hydrogen bond network of the solvating water cluster. Here, we report a broadband rotational spectroscopy study on the stepwise hydration of Gly with up to six water molecules. We reveal the preferred hydrogen bond networks formed when water molecules start to form three-dimensional (3D) topologies around an organic molecule. We observe that water self-aggregation prevails even in these early stages of microsolvation. These hydrogen bond networks manifest themselves through the insertion of the small sugar monomer in the pure water cluster in a way in which the oxygen atom framework and hydrogen bond network resemble those of the smallest three-dimensional pure water clusters. Of particular interest is the identification, in both the pentahydrate and hexahydrate, of the previously observed prismatic pure water heptamer motif. Our results show that some specific hydrogen bond networks are preferred and survive the solvation of a small organic molecule, mimicking those of pure water clusters. A many-body decomposition analysis of the interaction energy is also performed to rationalize the strength of a particular hydrogen bond, and it successfully confirms the experimental findings.

Water cluster structure in the MOF CAU-10-H: a powder diffraction perspective

Water cluster structure in the MOF CAU-10-H: a powder diffraction perspective

Intermolecular binding between bulk water and dissolved gases in earth's magnetic field.

Elucidation of the static states and dynamic behavior of oxygen and nitrogen dissolved in water is one of the most important issues in the life sciences. In the present study, experimental trials and theoretical calculations were performed based on the hypothesis that the dissolution of gas molecules in water is related to excitation by the Earth’s magnetic field. Using quantum theories such as those used to describe electro magnetic resonance and nuclear magnetic resonance, this study investigated the states of oxygen, nitrogen and hydrogen dissolved in water. The results indicate that the Earth’s magnetic field is involved in the bonding and dissociation of molecules at the gas-liquid interface. These calculations assessed the effect of a field strength of 1.0 x 10−4 T and reproduced the influences of temperature changes on dissolved gas concentrations. Molecular interactions caused by electromagnetic properties and the external geomagnetic field were found to affect intermolar bonding associated with water cluster structures. It is concluded that the binding between molecules typically attributed to Coulomb coupling by magnetic charge and van der Waals forces results from excitation in the Earth’s magnetic field.

Molecular modelling and computational studies of peptide diphenylalanine nanotubes, containing waters: structural and interactions analysis.

The work is devoted to computer studies of the structural and physical properties of such self-organizing structures as peptide nanotubes (PNT) based on diphenylalanine (FF) dipeptide with different initial isomers of the left (L-FF) and right (D-FF) chiralities of these dipeptides. The structures under study are considered both with empty anhydrous and with internal cavities filled with water molecules. Molecular models of both chiralities are investigated using quantum-chemical DFT and semi-empirical methods, which are in consistent with the known experimental data. To study the effect of nano-sized clusters of water molecules embedded in the inner hydrophilic cavity on the properties of nanotubes (including the changes in their dipole moments and polarizations), as well as the changes in the structure and properties of water clusters themselves (their own dipole moments and polarizations), the surfaces of internal cavities of nanotubes and outer surfaces of water cluster structures for both types of chirality are analyzed. A specially developed method of visual differential analysis of structural features of (bio)macromolecular structures is applied for these studies. The results obtained of a number of physical properties (interacting energies, dipole moments, polarization values) are given for various cases and analyzed in comparison with the known data. These data are necessary for analyzing the interactions of water molecules with hydrophilic parts of nanotube molecules based on FF, such as COO- and NH3 + , since they determine many properties of the structures under study. The data obtained are useful for further analysis of the possible adhesion and capture of medical molecular components by active layers of FF-based PNT, which can be designed for creating capsules for targeted delivery of pharmaceuticals and drugs on their basis.

Dynamic stability and management of supramolecular structures of water

The cluster structure of water is a recognized basis for studying the special properties of this liquid and, in particular, when interacting with biological systems.  An attempt has been made to identify patterns for the appearance of short-lived cluster supramolecular structures in the composition of water. They determine its effectiveness in relation to such biological systems. Their appearance is based on the patterns of bifurcation transition with a doubling of the number of bound molecules H2O. This is possible in a border area with chaos in intermolecular of bonds water. The use of I. Prigogine's principle of high-intensity fluctuations is proposed. They appear independently of changes in cluster structures in triatomic molecular associations based on the accumulation of internal energy to minimize dissipative processes. This is the basis for the organization of such stable structures with minimal change in the entropy of the entire system. Prigozhin's algorithm was applied to calculate the thermodynamic instability and behavior of triatomics as a control method. The index of the operator Liouville and the comparable criterion of stability of Lyapunov are involved. The processes of instantaneous reversibility and stability of short-lived clusters based on molecules were investigated, in full accordance with the existing provisions on the dynamic structure of water. The features of the action of high-frequency random oscillations are shown, which determine the periodicity of the creation of short-lived associations in the composition of water. It also shows the stability of such periodic processes in a limited period of time, as a basis for identifying repetitive states of the system. Energy interrelation in such systems is proposed to be considered as the basis to maintain their optimal state in the structure of water. This is also an indicator of its relationship to the perceiving biological systems

In English

The effect of the medium on the parameters of water bound to the surface of alginic acid powder was studied by low-temperature 1H NMR spectroscopy. The aim of this work was to study the effect of hydrophobic environment on the binding of water with alginic acid and to compare the parameters of the interfacial layers of water in air, in chloroform and chloroform with the addition of hydrochloric acid. It is shown that when adsorbed on the surface (500 mg/g H2O), most of it is strongly bound. It is shown that for most dispersed systems, when replacing the air with chloroform, the interfacial energy of water increases from 11.8 to 15.2 kJ/mol, which is due to the capability of weakly polar organic molecules to diffuse on the surface of solid particles, thereby reducing the interaction energy with the adsorbed surface water clusters. It is concluded that chloroform molecules cannot diffuse on the surface of alginic acid particles and affect only the structure of water clusters localized in the outer adsorption layer. In the presence of hydrochloric acid on the surface of alginic acid, a system of water clusters is formed, most of which does not dissolve hydrochloric acid, and the radii of these clusters is 2 nm, which are likely to form in the gaps between the polymer chains of polysaccharide.

Cluster characteristic of water used by energy facilities by total antiocidant activity

Energy facilities are located on most large reservoirs, therefore, the issue of water quality is especially acute in the water area of such water bodies. The article describes 9 clusters of water with values of total antioxidant activity, isolated now on the basis of numerous analyses. Water with a simplified structure is distinguished, containing 1 cluster and characterized water bodies with an abundance of life. Ordinary water with 2 clusters in the structure is water widely used by humans for household consumption. Water with 3-4 clusters observed in artesian wells. The most complex in cluster composition is spring water (5 clusters). The complex cluster structure of water made it possible to propose an index of water structure, which reflects the percentage of clusters with certain values of total antioxidant activity and the degree of water trophy. As a result, the work provides the recommendations on the values of total antioxidant activity of water at the water intake and offtake of combined Heat and Power plant.

Experimental methodology of water cluster doping

Water is one of the most common molecules in space and is also most valuable substance resource for living activities on earth. Studying water clusters plays an important role in actually utilizing water resources. Meanwhile, water clusters can be used as an ideal water microscopic model, which can expand the development of physical and chemical basic science, for example, it can provide the reference for investigating the size-dependent dissociation properties and interactions between solvents and solutes. On the other hand, the gas-phase mixed acidic water clusters have aroused great interest in recent years. For instance, One has been seeking for the smallest energy structure of pure water clusters and doped acidic molecular water clusters, experimentally and theoretically. In short, doping with foreign molecules or atoms can significantly enlarge the scope of scientific research on water clusters. Currently, there are many approaches to doping water clusters experimentally. This review briefly summarizes these means and compares the characteristics of various doping methods to help researchers to apply water cluster doping experiments more effectively.

Компьютерное моделирование и численные исследования пептидных нанотрубок на основе дифенилаланина

The work is devoted to computer studies of the structural and physical properties of such self-organizing structures as peptide nanotubes based on diphenylanine dipeptide with different initial isomers of the left and right chiralities of these dipeptides. The structures under study are considered both with empty anhydrous and with internal cavities filled with water molecules. Molecular models of both ring and helix structures are investigated, which are consistent with the known experimental data. To study the effect of nano-sized clusters of water molecules embedded in the inner hydrophilic cavity on the properties of nanotubes (including the changes in their dipole moments and polarizations), as well as the changes in the structure and properties of water clusters themselves (their dipole moments and polarizations), the surfaces of internal cavities of nanotubes and outer surfaces of water cluster structures for both types of chirality are analyzed. Including using a specially developed method of visual differential analysis of structural features of (bio)macromolecular structures. The obtained results of calculations of a number of physical properties (polarization values, etc.) are given for various cases and analyzed in comparison with the known data. These data are necessary for analyzing the interactions of water molecules with hydrophilic parts of nanotube molecules based on diphenylalanine, such as COO<sup>-</sup> and NH<sub>3</sub><sup>+</sup>, since they determine many properties of the structures under study. A number of the obtained data are planned to be used for further analysis of the possible adhesion and capture of certain medical molecular agents (components) by active layers of diphenylalanine-based nanotubes, which can be useful for creating capsules for targeted delivery of pharmaceuticals and drugs on their basis.

Synthesis, Crystal Structure and Luminescent Properties of a 3D Mg(II)−Sm(III) Heterometallic Coordination Polymer Containing 20‐member Water Clusters

AbstractA new Mg(II)−Sm(III) heterometallic coordination polymer (Cp) with the formula [Sm2(pydc)6Mg3(H2O)6] ⋅ 11H2O (1) (H2pydc=pyridine‐2,6‐dicarbolylic acid) has been solvothermal synthesized by reacting pyridine‐2,6‐dicarbolylic acid, Sm(NO3)3 ⋅ 6H2O, MgCl2 ⋅ 6H2O and imidazole at 393 K for 48 h. It was characterized by single‐crystal X‐ray diffraction, elemental analysis, IR and TGA. The results show that coordination polymer 1 exhibits a three‐dimensional network structure and crystallizes in hexagonal crystal system, space group P6/mcc, with crystallographic data of a=15.4203(6) Å, b=15.4203(6) Å, c=15.2563(6) Å, α=β=90°, γ=120°, V=3141.7(3) Å3, and Z=2. The twenty‐member water cluster structure and topological structure of compound 1 were analyzed, and its luminescent properties were studied. It presents the characteristic emission spectra of Sm(III) ions.

Structural Investigation of Sulfonated Polyphenylene Ionomers for the Design of Better Performing Proton-Conductive Membranes

To achieve high-performance proton-exchange membranes (PEMs), understanding of the polymer structure/property relationship is crucial. In particular, the structure of water clusters (number, size, ...

Structures of water clusters in the solvent phase and relative stability compared to gas phase

Most of biological and chemical processes occur in aqueous solution. To consider this solvent effects, theoretical investigations including explicit water molecules forming clusters are often considered. These clusters have been extensively investigated in the gas phase to understand their structures, energetics, dynamics, and several other properties. However, their structures, energetics, hydrogen bond networks and many other properties in the solvent phase remained unknown. In this work, we have investigated the effects of solvent on the structures, energetics and hydrogen bond networks of the water clusters from dimer to nonamer. We have explored thoroughly the potential energy surfaces (PESs) of the considered water clusters at classical level to generate initial geometries. The generated geometries have been fully optimized in the solvent phase (represented by a dielectric continuum medium) at the MN15/6-31++G(d,p) level of theory. For the description of the dielectric continuum medium we used the integral equation formalism polarized continuum model (IEF-PCM). The results show that the hydrogen bond network in the solvent phase is different from that in the gas phase due to further interaction with the dielectric continuum medium. Several structures located in the solvent phase are found to be unstable in the gas phase. Nevertheless, we have found that the global minimum structures in both phases have the same shape although their hydrogen bond lengths are different.

A look inside the black box: Using graph-theoretical descriptors to interpret a Continuous-Filter Convolutional Neural Network (CF-CNN) trained on the global and local minimum energy structures of neutral water clusters.

We describe a method for the post-hoc interpretation of a neural network (NN) trained on the global and local minima of neutral water clusters. We use the structures recently reported in a newly published database containing over 5 × 106 unique water cluster networks (H2O)N of size N = 3-30. The structural properties were first characterized using chemical descriptors derived from graph theory, identifying important trends in topology, connectivity, and polygon structure of the networks associated with the various minima. The code to generate the molecular graphs and compute the descriptors is available at https://github.com/exalearn/molecular-graph-descriptors, and the graphs are available alongside the original database at https://sites.uw.edu/wdbase/. A Continuous-Filter Convolutional Neural Network (CF-CNN) was trained on a subset of 500 000 networks to predict the potential energy, yielding a mean absolute error of 0.002 ± 0.002 kcal/mol per water molecule. Clusters of sizes not included in the training set exhibited errors of the same magnitude, indicating that the CF-CNN protocol accurately predicts energies of networks for both smaller and larger sizes than those used during training. The graph-theoretical descriptors were further employed to interpret the predictive power of the CF-CNN. Topological measures, such as the Wiener index, the average shortest path length, and the similarity index, suggested that all networks from the test set were within the range of values as the ones from the training set. The graph analysis suggests that larger errors appear when the mean degree and the number of polygons in the cluster lie further from the mean of the training set. This indicates that the structural space, and not just the chemical space, is an important factor to consider when designing training sets, as predictive errors can result when the structural composition is sufficiently different from the bulk of those in the training set. To this end, the developed descriptors are quite effective in explaining the results of the CF-CNN (a.k.a. the "black box") model.

Dissipative Particle Dynamics Modeling of Polyelectrolyte Membrane-Water Interfaces.

Previous experiments of water vapor penetration into polyelectrolyte membrane (PEM) thin films have indicated the influence of the water concentration gradient and polymer chemistry on the interface evolution, which will eventually affect the efficiency of the fuel cell operation. Moreover, PEMs of different side chains have shown differences in water cluster structure and diffusion. The evolution of the interface between water and polyelectrolyte membranes (PEMs), which are used in fuel cells and flow batteries, of three different side-chain lengths has been studied using dissipative particle dynamics (DPD) simulations. Higher and faster water uptake is usually beneficial in the operation of fuel cells and flow batteries. The simulated water uptake increased with the increasing side chain length. In addition, the water uptake was rapid initially and slowed down afterwards, which is in agreement with the experimental observations. The water cluster formation rate was also found to increase with the increasing side-chain length, whereas the water cluster shapes were unaffected. Water diffusion in the membranes, which affects proton mobility in the PEMs, increased with the side-chain length at all distances from the interface. In conclusion, side-chain length was found to have a strong influence on the interface water structure and water penetration rates, which can be harnessed for the better design of PEMs. Since the PEM can undergo cycles of dehydration and rehydration, faster water uptake increases the efficiency of these devices. We show that the longer side chains with backbone structure similar to Nafion should be more suitable for fuel cell/flow battery usage.

Кластерная структура воды и ее аргоно-подобное уравнение состояния

Кластерная структура воды и ее аргоно-подобное уравнение состояния

In Russian

By the methods of DSC, NMR spectroscopy and thermal analysis, the state of water in partially dehydrated cell cultures of the Tibetan milk fungus was studied. It was found that when the water content in the samples is up to 0.8 g/g, all water is associated with cellular structures. Water is predominantly in a highly associated state, when there are 2-3 hydrogen bonds per molecule. In air at CH2O = 0.3 g/g, most of the water is part of clusters with a radius of R = 10 nm. With an increase in water concentration to 0.8 g/g, three maxima are present on the distribution curves at R = 1, 2, and 12 nm. The same maxima are also present when air is replaced by a chloroform medium. It is possible to differentiate the structure of various water clusters in the cellular systems of a Tibetan milk fungus using chloroform medium with the addition of trifluoroacetic acid. In this case, in the 1H NMR spectra there are four water signals related to clusters having different dissolving powers with respect to acid. About half of the bound water is part of acid-insoluble clusters. Two endothermic peaks are recorded on thermograms of thawing of a pure dean. One at T = -28 °C, which coincides with the passport melting point of the dea, and the second at T = -8 °C. Probably, part of the decane is able to maintain crystallinity at a temperature significantly higher than the melting temperature of the bulk of the substance. On the DSC curves of thawing of a sample of milk fungus biomaterial containing equal amounts of adsorbed water and decane, several endothermic maxima are observed. Considering that at the chosen concentration, the peak of water defrosting is not observed, the most intense peaks (T = -28 and T = -25 °C) should be attributed to the process of dean melting. Peaks of lower intensity can also be associated with the melting of various forms of crystalline decane stabilized by the surface of the biomaterial