Three-channel 300 MHz solid-state NMR spectrometer console

• Subject Area: Molecular Chemistry
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573609709

The University of Bayreuth requests the replacement of a 20-year-old three-channel console for its 300 MHz solid-state NMR spectrometer, which is operated within the Northern Bavarian NMR Centre (NBNC). Currently, 32 research groups in bio-, life, food, and materials science, polymer and colloid chemistry, molecular research, geosciences, and high-temperature/high-pressure research are working within the NBNC, and one-third of these members utilise solid-state NMR spectroscopy. This demand is met with four WB spectrometers, with proton fre-quencies ranging from 300 MHz to 600 MHz. The spectrometers are assigned to specific application areas for probing structure, dynamics and long-range transport. They are thus all required to maintain NBNC’s full capability to use solid-state NMR spectroscopy. The 300 MHz solid-state WB spectrometer is reserved for experiments with hyperpolarised 129Xe for probing porous materials and for measurements where low magnetic fields are ad-vantageous. Materials that are often paramagnetic, such as metal-organic frameworks, mo-lecular cages, and battery materials, are measured at this spectrometer to limit anisotropic contributions to the lineshapes. The same argument applies to materials like hybrid perov-skites, containing heavy nuclei (119Sn, 207Pb) with large chemical shift anisotropies (CSA). For these cases, ultrafast spinning is essential, and the new console should be equipped with a MAS unit compatible with rotor diameters as small as 0.7 mm. The available 4 and 7 mm MAS triple-resonance probes, furthermore, allow for taking advantage of the larger sample quanti-ties that are beneficial for materials containing nuclei with low natural abundance and moder-ate CSA, such as 13C, 15N, and 29Si. Additionally, sequences such as CP and CPPI are more sensitive when combined with slow spinning. With the advanced electronics of the new con-sole, we also plan to perform 2D correlation experiments such as 1H-X HETCOR, 1H-19F-HETCOR, 1H-X-Y double-CP, and 1H-X, X-Y, 1H-19F REDOR and make use of multi-detection schemes. The broad range of material classes and planned experiments necessitates three channels. Their high-power amplifiers should be selected in a way that at least two channels can excite heteronuclei with frequencies between 109Ag and 31P, and two amplifiers can excite 1H and 19F. Regarding the amplifier power, at least 500 W is required twice, and 1 kW is required once. The three channels should be equipped with individual detection units and a fast DSP pulse programmer to enable the use of multi-detection schemes and CRAMPS sequences, thereby improving the ¹H resolution in the indirect dimension of 2D NMR spectra. With the new con-sole, the 129Xe hyperpolariser and the available triple-resonance MAS flow probe, can be used to transfer polarisation from adsorbed, hyperpolarised 129Xe atoms to 1H or other X nuclei at the pore surfaces, which requires employing symmetry-based sequences.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Drei-Kanal-Konsole 300MHz-Festkörper-NMR-Spektrometer
• Instrumentation Group: 1741 Festkörper-NMR-Spektrometer
• Applicant Institution: Universität Bayreuth
• Leader: Professor Dr. Jürgen Senker