Pressure and Temperature Effects on ^2H-NMR Spin-Lattice Relaxation Times in TBA-and Urea-D_2O Solutions
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The <SUB>2</SUB>H NMR spin-lattice relaxation times (T<SUB>1</SUB>) of D<SUB>2</SUB>O molecules and the <SUP>1</SUP>H chemical shifts (δ) of water in tert-butyl alcohol (TBA) -and urea-D<SUB>2</SUB>O solutions up to 8 mol% were measured at 7. 7, 29. 9, and 48. 4°C up to 294 MPa in order to elucidate the pressure and temperature effects on the hydrophobic hydration. The pressure coefficient of T<SUB>1</SUB> in the TBA solution was smaller than that in pure water, and decreased monotonously with an increase in the TBA content. The δ (H<SUB>2</SUB>O) in the TBA solution exhibits a downfield shift relative to that in neat D<SUB>2</SUB>O and the difference in the δ (H<SUB>2</SUB>O) between TBA solution and neat D<SUB>2</SUB>O becomes larger with compression. These results suggest that the structure of the hydration shell is not so bulky as the tetrahedral open structure of water. On the other hand, the results in urea solutions were in marked contrast to those in TBA solutions.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 1159-1161, 1998
The Japan Society of High Pressure Science and Technology