A Facile Strategy to Prepare Small Water Clusters via Interacting with Functional Molecules

Abstract

Although small water clusters (SWCs) are important in many research fields, efficient methods of preparing SWCs are still rarely reported, which is mainly due to the lack of related materials and understanding of the molecular interaction mechanisms. In this study, a series of functional molecules were added in water to obtain small water cluster systems. The decreasing rate of the half-peak width in a sodium dodecyl sulfate (SDS)–water system reaches ≈20% at 0.05 mM from 17O nuclear magnetic resonance (NMR) results. Based on density functional theory (DFT) and molecular dynamics (MD) simulation calculation, it can be concluded that functional molecules with stronger negative electrostatic potential (ESP) and higher hydrophilicity have a stronger ability to destroy big water clusters. Notably, the concentrations of our selected molecule systems are one to two magnitudes lower than that of previous reports. This study provides a promising way to optimize aqueous systems in various fields such as oilfield development, protein stability, and metal anti-corrosion.

Exploration of the Existence Forms and Patterns of Dissolved Oxygen Molecules in Water

“…As can be seen in Fig. 2 , a significant negative correlation between the saturated concentration of dissolved oxygen and the size of water clusters could be observed: the lower the half-peak width of the NMR spectrum, the smaller the water clusters [ 50 ], and consequently, the higher the concentration of dissolved oxygen.

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“…Since the transverse relaxation process involves the exchange of spin states between adjacent nuclei, and the larger the size of water clusters, the faster the exchange of spin states between oxygen or hydrogen nuclei and adjacent nuclei, the shorter the time required for the sample to return to equilibrium, resulting in a wider spectral line [46][47][48]. As a result, while using NMR to analyze the distribution of hydrogen nuclei in water molecules, the size of water molecular clusters can be concluded as well [49,50]. Also, it is possible to understand how fast these water molecules are moving: the slower the molecules motion, the larger the molecular size, the shorter the relaxation time, and the wider the half-peak width is [51].…”