| Osmolality | Fully dissociated into 2 Na⁺ and B₁₂X₁₂²⁻ at the concentrations studied |
|---|---|
| Raman-MCR hydration-shell spectroscopy, 50 mM, OH-stretch region | A relatively sharp band above 3500 cm⁻¹ and a broad band below 3500 cm⁻¹; total band area scaled linearly with B₁₂X₁₂²⁻ concentration |
| Raman-MCR hydration-shell spectroscopy, band assignment below 3500 cm⁻¹ | A major liquid-like population around 3400 cm⁻¹ and a minor ice-like population around 3200 cm⁻¹ for Na₂B₁₂I₁₂, Na₂B₁₂Br₁₂, and Na₂B₁₂H₁₂; only the liquid-like population for Na₂B₁₂Cl₁₂. In 90 % D₂O + 10 % H₂O, the putative ice-like population was suppressed |
| Raman-MCR hydration-shell spectroscopy, band assignment above 3500 cm⁻¹ | OH groups oriented toward B₁₂X₁₂²⁻ and forming weak O–Hδ⁺···Xδ⁻–B hydrogen bonds; Raman-shift order B₁₂H₁₂²⁻ < B₁₂I₁₂²⁻ < B₁₂Br₁₂²⁻ < B₁₂Cl₁₂²⁻ |
| Temperature-dependent Raman-MCR hydration-shell spectroscopy, 50 mM, 5, 25, 45, 65, and 85 °C | For B₁₂Br₁₂²⁻, intensity at 3200 cm⁻¹ decreased slightly on heating, intensity at 3450 cm⁻¹ increased more markedly, and the 3600 cm⁻¹ band remained at the same position and varied slightly in magnitude; the other ions showed analogous temperature trends. The neat-water OH-band centroid blue-shifted more strongly than the hydration-water centroid, and the hydration-water/neat-water centroid ratio decreased toward 1.00 with increasing temperature |
| Raman-band-centroid hydrogen-bond energy estimate, B₁₂Br₁₂²⁻ hydration water released into bulk water | −5.8 kJ mol⁻¹ at 5 °C; −4.9 kJ mol⁻¹ at 85 °C |
Max Hohenschutz, Chin-Yi Chen, Vighnesh B. Lokare, Patrick Denk, Paul S. Cremer. “Hydration shell structure and water-mediated binding of closo-dodecaborates probed by Raman hydration-shell spectroscopy.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007801/v1
Values presented only in Raman, osmolality and cloud-point plots or images were not transcribed. The main paper refers to supporting information, but no separate supporting information file was found among the files available from the ChemRxiv record
| Hydroxypropylcellulose sample | Viscosity-average degree of polymerization N = 230; 3.8 hydroxypropyl groups per glucose unit; Mᵥ/Mₙ = 2.0 |
|---|---|
| Raman-MCR hydration-shell spectroscopy, 130 mM hydroxypropylcellulose | C–H stretch band with four resonances below 3000 cm⁻¹; OH-stretch maxima at 3200 and 3400 cm⁻¹ |
| Raman-MCR hydration-shell spectroscopy, 50 mM Na₂B₁₂Br₁₂ and 130 mM hydroxypropylcellulose, 25 °C | Bands at 3200 and 3400 cm⁻¹ were higher than for hydroxypropylcellulose alone; the B₁₂Br₁₂²⁻ hydration-shell band at 3600 cm⁻¹ was smaller than for B₁₂Br₁₂²⁻ in water; the C–H stretch of hydroxypropylcellulose changed in shape and intensity |
| Released-water Raman spectra, 50 mM Na₂B₁₂X₁₂ and 130 mM hydroxypropylcellulose | Two Gaussian OH-stretch bands: a sharp peak just below 3600 cm⁻¹ and a broad peak just above 3400 cm⁻¹. The sharp peak represented 26–39 % of the total band area, depending on the B₁₂X₁₂²⁻ species. Total OH-band-area order: B₁₂H₁₂²⁻ < B₁₂Cl₁₂²⁻ < B₁₂Br₁₂²⁻ < B₁₂I₁₂²⁻ |
| Released-water Raman band areas, 50 mM | 2, 5, 6, and 7 water molecules released per added B₁₂H₁₂²⁻, B₁₂Cl₁₂²⁻, B₁₂Br₁₂²⁻, and B₁₂I₁₂²⁻, respectively |
| Released-water Raman spectra, B₁₂Br₁₂²⁻ concentration series with 130 mM hydroxypropylcellulose | Spectral shape and Gaussian band-area fractions were independent of concentration; the total band area followed a saturation curve and was fitted with a Langmuir isotherm, Kₐ = 53 ± 8 M⁻¹; released water decreased from 18 molecules per added B₁₂Br₁₂²⁻ at 5 mM to 4 at 100 mM |