Experiment-based new insights into hydrogen bonds between alcohol and water through reduced-hydrogen-bonded plasmon-activated water

Abstract

The molecular structure of water and alcohol connected by hydrogen bonds (HBs) remains unclear. In this study, innovative plasmon-activated water (PAW) with fewer HBs was produced from bulk deionized water (DIW). The HBs between pure ethanol and water were stronger than those of pure DIW, which was confirmed by analyses of measured densities and the spectra of nuclear magnetic resonance (NMR) T1 and Raman OH-stretching of PAW with fewer HBs for the first time. Moreover, the intrinsic HBs between hydrophilic alcohol molecules were destroyed by hot electron transfer, reducing the original HBs, such as in PAW. For extremely polar DIW, the degree of non–hydrogen-bonded water (DNHBW) was approximately 0.21. For alcohols, the non–hydrogen-bonded alcohol (DNHBA) was also first similarly defined. The calculated values of DNHBA are 0.48, 0.68, and 0.87 for methanol, ethanol, and propanol, respectively. These values were consistent with their corresponding solvent polarities and HB strength. Moreover, the relative intensity of weak HBs (RIWHBs) is first defined utilizing the Raman spectra of water and alcohol/water mixtures. The calculated values of RIWHBs were consistent with our recognized strength of HBs of alcohol/water mixtures, as illustrated by PAW with intrinsically reduced HBs.