Using a laser monitoring technique, the solubilities of 1,1′-(butane-1,4-diyl)-bis(pyridinium) dihexafluorophosphate in acetone (1) + water (2) have been determined experimentally from (278.15 to 328.15) K at atmospheric pressure. The experimental data were correlated with the modified Apelblat equation and the λh model. The calculated results showed good agreement with the experimental data. The solubility of 1,1′-(butane-1,4-diyl)-bis(pyridinium) dihexafluorophosphate in acetone + water is higher than that in water and acetone, respectively, and reaches the maximum value when the mass fraction w 2 ) 0.30.

In single-atom catalysts (SACs), the complexity of the support anchoring sites creates a vast diversity of single-atom species with varied coordination environments. To date, the quantitative distribution of these diverse single-atom species in a given SAC has remained elusive. Recently, CeO2-supported metal SACs have been extensively studied by modulating their local environments via numerous synthetic strategies. However, owing to the absence of a quantitative description, unraveling the site-specific reactivity and regulating their transformation remain challenging. Here, we show that two distinct Pt/CeO2 SACs can be reversibly generated by oxidative and nonoxidative dispersions, which contain varied Pt1O n –Ceδ+ single-atom species despite similar Pt charge states and coordination numbers. By means of Raman spectroscopy and computational studies, we semiquantitatively reveal the distribution of diverse Pt1O n –Ceδ+ species in each specific SACs. Remarkably, the minority species of Pt1O4–Ce3+–Ov accounting for only 14.2% affords the highest site-specific reactivity for low-temperature CO oxidation among the other abundant counterparts, i.e., Pt1O4–Ce4+ and Pt1O6–Ce4+. The second nearest oxygen vacancy (Ov) not only acts synergistically with the nearby active metal sites to lower the reaction barrier but also facilitates the dynamic transformation from six-coordinated to four-coordinated sites during cyclic nonoxidative and oxidative dispersions. This work elucidates the quantitative distribution and dynamic transformation of varied single-atom species in a given SAC, offering a more intrinsic descriptor and quantitative measure to depict the inhomogeneity of SACs.

Using a laser monitoring observation technique, the solubilities of 1-ethylpyridinium hexafluorophosphate in ethanol + water binary solvent mixtures have been measured from (278.15 to 345.15) K. The experimental data were well correlated with the modified Apelblat equation. The solubility of 1-ethylpyridinium hexafluorophosphate in ethanol + water is higher than that in water and ethanol, respectively, and reaches the maximum value when the mass fraction (w) of water in the ethanol + water binary solvent mixtures is equal to 0.40.

The solubilities of triadimefon in acetone + water were measured at temperatures from (278.15 to 333.15) K by a synthetic method at atmospheric pressure. The experimental data were well correlated with the modified Apelblat equation.

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