Differentiation and identification of enantiomers by nuclear magnetic resonance spectroscopy with support of quantum mechanical computations

We report nuclear magnetic resonance studies of two chiral building blocks of solifenacin, phenyltetrahydroisoquinoline and quinuclidinol, in which chiral solvating agents, Mosher's acid, and Pirkle's alcohol were used for spectral discrimination between enantiomers of solifenacin constituents. Based on the constraints following from measurements of the nuclear Overhauser effect, structures of phenyltetrahydroisoquinoline and Pirkle's alcohol solvates were found. Next, shifts of nuclear magnetic resonance signals of phenyltetrahydroisoquinoline due to the application of Pirkle's alcohol were computed using density functional theory methods. The computed carbon-13 shifts reproduce those determined experimentally, allowing us to attribute the absolute configuration to phenyltetrahydroisoquinoline enantiomers without the need for the use of empirical rules.

Lithium Transport Studies on Chloride-Doped Argyrodites as Electrolytes for Solid-State Batteries

In this study, the activation energy and ionic conductivity of the Li6PS5Cl material for all-solid-state batteries were investigated using solid-state nuclear magnetic resonance (NMR) spectroscopy and electrochemical impedance spectroscopy (EIS). The results show that the activation energy values estimated from nuclear relaxation rates are significantly lower than those obtained from impedance measurements. The total ionic conductivities for long-range lithium diffusion in Li6PS5Cl calculated from EIS studies depend on the crystal size and unit cell parameter. The study also presents a new sample preparation method for measuring activation energy using temperature-dependent EIS and compares the results with the solid-state NMR data. The activation energy for a thin-film sample is equivalent to the long-range lithium dynamics estimated from NMR measurements, indicating the presence of additional limiting processes in thick pellets. Additionally, a theoretical model of Li-ion hopping based on results obtained using density-functional theory methods in comparison with experimental findings was discussed. Overall, the study emphasizes the importance of sample preparation methods in determining accurate activation energy and ionic conductivity values for solid-state lithium batteries and the significance of solid-state electrolyte thickness in new solid-state battery design for faster Li-ion diffusion.