Analytical Instrument Documents

JEOL NMR systems have had all FDA 21 CFR Part 11 support functions available in the standard Delta software since version 4.3 was released in 2004. All newer versions of the software have maintained and added to this functionality.

JEOL offers a full range of Magic-Angle-Spinning (MAS) probes and tools matched to a wide variety of solid-state NMR applications. JEOL MAS probes feature sample tube diameters to match the user sample and sensitivity needs. JEOL narrow bore MAS probes offer improved stability for high-speed spinning or for very large volumes. The JNM-ECZ Series NMR Spectrometer automatically updates the relevant spectrometer settings for all NMR probes for fast and easy switching between solids and liquids NMR operation.

The ECZS NMR spectrometer (JNM-ECZS series) has functionality and performance of the high-end ECZR series, yet in a compact, space saving design. Through the combination of advanced software with highly reliable hardware, all routine measurements can be automated. Using high sensitivity auto tune probes, including the optional SuperCOOL probe which features cryogenically cooled technologies, JNM-ECZS affords the world’s best-in-class sensitivity. The high performance can be demonstrated in many application fields.

The JNM-ECZR NMR spectrometer (JNM-ECZR series), a member of the JNM-ECZ series of instruments, is a new research system that fully incorporates the latest digital and high frequency technologies. Highly reliable, yet in a more compact size made possible by incorporating advanced integrated circuits, it supports even greater expandability options than past models for multi-channel operation, high power amplifiers and other accessories. The bus line for control of attachments has been upgraded to even higher speed and enables highly accurate and rapid control.

Solid-state NMR spectroscopy has played a significant role in elucidating the structure and dynamics of materials and biological solids at a molecular level for decades. In particular, the 1H double-quantum/single-quantum (DQ/SQ) chemical shift correlation experiment is widely used for probing the proximity of protons, rendering it a powerful tool for elucidating the hydrogen-bonding interactions and molecular packing of various complex molecular systems. Two factors, namely, the DQ filtering efficiency and t1-noise, dictate the quality of the 2D 1H DQ/SQ spectra. Experimentally different recoupling sequences show varied DQ filtering efficiencies and t1-noise. Herein, after a systematic search of symmetry-based DQ recoupling sequences, we report that the symmetry-based γ-encoded sequences show superior performance to other DQ recoupling sequences, which not only have a higher DQ recoupling efficiency but can also significantly reduce t1-noise. The origin of t1-noise is further discussed in detail via extensive numerical simulations. We envisage that such γ-encoded sequences are superior candidates for DQ recoupling in proton-based solid-state NMR spectroscopy due to its capability of efficiently exciting DQ coherences and suppressing t1-noise.

Proton-detected solid-state NMR at fast Magic Angle Spinning (MAS) is becoming the norm to characterize molecules. Routinely 1H–1H and 1H-X dipolar couplings are used to characterize the structure and dynamics of molecules. Selective proton recoupling techniques are emerging as a method for structural characterization via estimation of qualitative and quantitative distances. In the present study, we demonstrate through numerical simulations and experiments that the well-characterized CNvn sequences can also be tailored for selective recoupling of proton spins by employing C elements of the type (β)Φ(4β)Φ+π(3β)Φ. Herein, several CNvn sequences were examined through numerical simulations and experiments. C614 recoupling sequence with a modified POST-element ((β)Φ(4β)Φ+π(3β)Φ) shows selective polarization transfer efficiencies on the order of 40–50% between various proton spin pairs in fully protonated samples at rf amplitudes ranging from 0.3 to 0.8 times the MAS frequency. These selective recoupling sequences have been labeled as frequency-selective-CNvn sequences. The extent of selectivity, polarization transfer efficiency and the feasibility of experimentally measuring proton-proton distances in fully protonated samples are explored here. The development of efficient and robust selective 1H–1H recoupling experiments is required to structurally characterize molecules without artificial isotope enrichment or the need for diffracting crystals.

Highlights: • Selective detection of 1H signals of API in a tablet formulation is proposed. • 1H signals of excipients are suppressed. • 1H signals in the vicinity of nuclei (here 14N) which only appear in API are excited. • 1H{14N} magnetization is diffused to 1Hs in API crystals by RFDR recoupling.

This experimental approach allows direct correlation of JCC values with specific molecular conformations since, in crystalline samples, molecular conformation is essentially static and can be determined by X-ray crystallography.

A collaborative paper was published in Tetrahedron. The INADEQUATE spectrum discussed in this research was obtained using a cryogenic probe (UltraCOOL probe) in liquid helium in a JEOL 800 MHz spectrometer (JNM-ECZ800R).

We propose a dynamic covalent chemistry (DCC)-induced linker exchange strategy for the structural transformation between covalent organic frameworks (COFs) and cages for the first time. Studies have shown that the COF-to-cage and cage-to-COF transformations were realized by using borate bonds and imine bonds, respectively, as linkages. Self-sorting experiments suggested that borate cages and imine COFs are thermodynamic minimum compounds. This research builds a bridge between discrete and polymeric organic scaffolds and broadens the knowledge of chemistry and materials for porous materials science.