Analytical Instrument Documents

1H, in principle, is very useful nucleus to investigate atomic-resolution structures and dynamics due to its high abundance (>99%) and gyromagnetic ratio (600 MHz at 14.1T). In fact 1H is the first choice of nucleus in solution NMR. On the other hand, 1H NMR of rigid solids is much less common. This is because 1H solid-state NMR gives very broad (~50 kHz) and featureless spectra (Fig 1a) due to strong 1H-1H dipolar coupling, which is dynamically averaged out in solution. Magic angle spinning (MAS) removes the broadening to the first order, but is not enough to achieve high resolution 1H NMR at moderate MAS rate (Fig 1b). Tremendous efforts were made to overcome this issue from the early dates of solid-state NMR towards high-resolution 1H NMR [1]. Most of them combine MAS with sophisticated 1H pulses which is dubbed CRAMPS (combined rotation and multiple pulse spectroscopy). Nowadays very fast MAS > 60 kHz can be used to achieve high-resolution 1H solid-state NMR (Fig 1c) [2]. However, the traditional CRAMPS is still useful as that can be performed with very conventional solid-state NMR equipment, for example 4 mm MAS probe with a 400 MHz spectrometer. Moreover, wPMLG at moderate MAS rate often overwhelms fast MAS in terms of resolution. In this note, we will describe tutorial guidance to optimize experimental parameters for CRAMPS.

Multidimensional correlation NMR spectroscopies, which provides inter-nuclear proximity/connectivity, play a crucial role to probe the atomic resolution structures. Especially, 1H-1H homonuclear correlation spectroscopy is quite useful source of information because of high abundance (>99%) and gyromagnetic ratio, thus resulting in strong inter nuclear interactions. Thanks to the development of high resolution 1H solid-state NMR, now it is feasible to observe 1H-1H correlation high resolution solid-state NMR [1]. There are two distinctive categories; 1) single quantum (SQ)/SQ correlation and 2) double quantum (DQ)/SQ correlations. In this note we introduce 2D 1H SQ/ 1H SQ and 1H DQ/ 1H SQ correlation spectroscopy to probe the internuclear proximity using high-resolution 1H solid-state NMR techniques.

Lithium ion secondary batteries using spinel-type lithium titanium oxide (LTO) as the negative electrode material are excellent in safety and cycle characteristics due to their chemical stability, and have already been put into practical use.

In comparison with the UltraCOOL probe, SuperCOOL probe represents a cryogenic probe with high sensitivity at lower cost and power consumption. Thermal noise reduction due to new designed cooling system greatly enhances the sensitivity of NMR measurement.

It is often difficult to unambiguously determine structures of molecules, which have many non-protonated carbon atoms. Because such compounds contain quaternary carbons, lack protons and bonding to quaternary carbons each other, HMBC (Heteronuclear Multiple Bond Correlation) experiment cannot provide long-range 1H-13C connectivity. Therefore, INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment), which is 13C-13C correlation experiment at natural 13C abundance, represents a powerful tool for proton-diluted compounds.

Here, we combine ED and solid-state NMR through the first principle quantum computation with the NMR crystallography approach for crystalline structure solution. The method, electron and NMR nano-crystallography, can be applied to nano- to micro-crystals even for mixture samples.

Solid state NMR is a powerful tool to obtain information in the crystalline state which would be lost in the solution state.

The low oral bioavailability of a drug due to its poor aqueous solubility is a major challenge for pharmaceutical development. Solid dispersion (SD), where the amorphous drug is dispersed into the polymer matrix, is one of the useful approaches to improve the aqueous solubility. However, thermodynamically unstable nature of an amorphous drug increases its susceptibility to recrystallize upon storage, which, in turn, reduces its solubility and dissolution. Therefore, design of thermodynamically stable SD is required.

15N NMR is widely used because of the importance of nitrogen in chemistry, materials, biology, environment, etc. However, very low abundance of 15N (<0.4%) results in poor sensitivity and thus makes observation time-consuming. On the other hand, the rest of nitrogen atoms are also NMR sensitive nucleus of 14N. Despite the high abundance of 14N (>99%), it's application is rather limited due to the huge quadrupolar interactions and its spin quantum number I = 1.

JEOL AUTOMAS probe combined with Auto Sample Changer and Auto Tune Unit allows for fully automated solid NMR measurements including sample load/eject, tuning and matching, magic angle spinning frequency control, and temperature control. This enables you to manage efficient data collection as liquid NMR.