Upgrade 600-MHz-NMR Spectrometer

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The "Central NMR Laboratory of the Chemical Institutes" is a joint facility of the Institute of Inorganic and Analytical Chemistry and the Institute of Organic Chemistry at the TU Braunschweig. It provides NMR-spectroscopic services and know-how throughout the university. Natural substances as well as organic, inorganic, organometallic and macromolecular synthesis products are examined, which are obtained or manufactured in the chemical, biological, pharmaceutical and materials science institutes of the university. So far, the most sensitive of the five NMR spectrometers available here has been a 600 MHz device with a He-cooled inverse triple resonance cryo probe (1H/13C/15N; 15N only indirectly). Due to total damage to the probehead and its peripheral devices after approx. 110,000 operating hours (2006-2019), the spectrometer no longer fulfills its main purpose, namely the examination of samples with maximum detection sensitivity. As the consequence, spectra acquisitions require a multiple of the previous measurement time or are useless for very small amounts of substance. This causes severe capacity problems, indirectly also on the other spectrometers, especially on the 500 MHz device. To restore the performance and modernize the 600 MHz spectrometer, a partial replacement of the device is necessary. While the magnet and one probehead (not a cryo head: broadband observe 31P-15N/1H) will remain in use, we intend to replace of the 14-year-old spectrometer console (technically outdated; with serious spare parts problems; “end of service” announced already for the end of 2017) including the automatic sample changer and the defective cryo equipment. The latter include cryo cooling unit, He compressor, He-cooled inverse triple resonance cryo probehead with a suitable temperature control option.New components are required that restore at least the full performance of the original device. Therefore, as before, the focus is on maximum 1H sensitivity and, at the same time, the highest possible 13C and 15N sensitivity in order to complement the other spectrometers. In view of the diversity of the working groups, weaknesses of the previous equipment (e.g. 19F not observable; 15N not directly observable; temperature range of the cryo probehead too small, 0-80 °C) should be eliminated.We therefore apply for the following components: 600 MHz spectrometer console with three frequency channels, cryo equipment with He-cooled inverse triple resonance cryo probe head (1H&19F/13C/15N; 15N also directly observable) for the largest possible temperature range, automatic sample changer for optimal use of the device .Resulting improvements will be: restoration of maximum sensitivity (extremely important), feasibility of state-of-the-art NMR experiments (e.g. "NOAH"); direct observation of 19F and 15N; accessible temperature range -40 to +150 ° C.