Long-lived water clusters in hydrophobic solvents investigated by standard NMR techniques

Abstract

Unusual physical characteristics of water can be easier explained and understood if properties of water clusters are revealed. Experimental investigation of water clusters has been reported by highly specialized equipment and/or harsh experimental conditions and has not determined the properties and the formation processes. In the current work, we used standard 1H-NMR as a versatile and facile tool to quantitatively investigate water clusters in the liquid phase under ambient conditions. This approach allows collection of data regarding the formation, long lifetime, stability, and physical properties of water clusters, as a cubic octamer in the liquid phase.

Comparison of single-phase and two-phase measurements in extraction, separation and back-extraction of Cd, Zn and Co from a multi-element matrix using Aliquat 336

“…From the literature, there is experimental data that indicate which Cd(II) and Zn(II) can force water away from A336 [103]. In addition the small peak at 2.6 to 2.8 can tentatively be assigned to clusters of water under the assumption that benzene and toluene have similar behaviour [104]. This agrees with what was observed in the work presented here.…”

Water transport through epoxy-based powder pipeline coatings

“…Additionally, the slight decrease of permeability between 40 and 65ºC in Figure 5 was also in accord with reports of water clustering effects in epoxy above 45°C, where the 'water-induced microvoid' situation became kinetically favorable due to its endothermic nature [48]. Previous work in the literature [56] has shown through thermodynamic characterization of water clusters that formation of a more ordered structure from dissolved water has large enthalpy gain and entropy loss, resulting in a slightly negative ∆𝐺. Specifically, the thermodynamically metastable state of water due to clustering slows the transmission rate through the polymeric network, resulting in a significant decrease of diffusivity of water molecules in the highly ordered water clusters.…”

Proton Exchange of Intracyclic NH Groups of Deuteroporphyrin IX Dimethyl Ester and Water Molecules according to the Data of Exchange Spectroscopy (EXSY)

“…Как было отмечено k W = 5.8 ± 0.4 с -1 , [8] E a (W) = 27.3 ± 1.3 кДж/моль, [8] стадии 1, 6; k NH = 0.67 ± 0.03 с -1 , [8] E a (NH) = 15.8 ± 0.7 кДж/моль, [8] В то время, как распад ассоциата порфирин-вода является реакцией первого порядка (Схема 1, стадии 2, 5), образование ассоциата порфирин-вода непосредственно из ассоциата молекулы воды с двумя молекулами бензола должно быть реакцией второго порядка, что не соответствует экспериментальным данным. В связи с этим логично предположить, что образованию ассоциата порфирин-вода предшествует формирование менее прочного сольвата молекулы воды, аналогичного описанному в работах [24][25][26] (Схема 1, стадии 1 и 6). Эта реакция должна иметь первый порядок, она может быть лимитирующей стадией и в таком случае определяет скорость образования ассоциата в целом.…”