SABRE catalysts [Ir(H)2(η2-pyruvate)(sulfoxide)(NCH) transfer magnetisation from para-hydrogen to pyruvate yielding hyperpolarised 13C NMR signals enhanced by >2000-fold. Properties of the catalyst control efficiency.
The
conversion of [IrCl(COD)(IMes)] (COD = cis,cis-1,5-cyclooctadiene, IMes = 1,3-bis(2,4,6-trimethyl-phenyl)imidazole-2-ylidene)
in the presence of an excess of para-hydrogen (p-H2) and a substrate (4-aminopyridine (4-AP) or 4-methylpyridine (4-MP)) into [Ir(H)2(IMes)(substrate)3]Cl is monitored by 1H NMR spectroscopy using a benchtop (1 T) spectrometer in conjunction
with the p-H2-based hyperpolarization
technique signal amplification by reversible exchange (SABRE). A series
of single-shot 1H NMR measurements are used to monitor
the chemical changes that take place in solution through the lifetime
of the hyperpolarized response. Non-hyperpolarized high-field 1H NMR control measurements were also undertaken to confirm
that the observed time-dependent changes relate directly to the underlying
chemical evolution. The formation of [Ir(H)2(IMes)(substrate)3]Cl is further linked to the hydrogen isotope exchange (HIE)
reaction, which leads to the incorporation of deuterium into the ortho positions of 4-AP, where the source of
deuterium is the solvent, methanol-d4.
Comparable reaction monitoring results are achieved at both high-field
(9.4 T) and low-field (1 T). It is notable that the low sensitivity
of the benchtop (1 T) NMR enables the use of protio solvents, which when used here allows the effects of catalyst formation
and substrate deuteration to be separated. Collectively, these methods illustrate how low-cost low-field NMR
measurements provide unique insight into a complex catalytic process
through a combination of hyperpolarization and relaxation data.
Benchtop NMR spectrometers operating with magnetic fields of 1–2 T at sub-ppm resolution coupled with SABRE hyperpolarization show great promise as analytical platforms that can be used outside the traditional laboratory environment.
Early warning systems detect new psychoactive substances (NPS), while dedicated monitoring programs and routine drug and toxicology testing identify fluctuations in prevalence. We report the increasing prevalence of the synthetic cannabinoid recep-. ADB-BUTINACA was first detected in a seizure in Sweden in 2019, and we report its detection in 13 routine Swedish forensic toxicology cases soon after. In January 2021, ADB-BUTINACA was detected in SCRA-infused papers seized in Scottish prisons and has rapidly increased in prevalence, being detected in 60.4% of the SCRA-infused papers tested between January and July 2021. In this work, ADB-BUTINACA was incubated with human hepatocytes Robert Kronstrand, Craig McKenzie, and Henrik Green contributed equally to the study.
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