Using ²H labelling to improve the NMR detectability of pyridine and its derivatives by SABRE

Abstract

By introducing a range of 2H labels into pyridine and the para‐substituted agents, methyl isonicotinate and isonicotinamide, we significantly improve their NMR detectability in conjunction with the signal amplification by reversible exchange process. We describe how the rates of T 1 relaxation for the remaining 1H nuclei are increased and show how this leads to a concomitant increase in the level of 1H and 13C hyperpolarization that can ultimately be detected.

Simulating Non‐linear Chemical and Physical (CAP) Dynamics of Signal Amplification By Reversible Exchange (SABRE)

“…The “SABRE formula” was the first attempt to explicitly include the chemical reaction, relaxation, and polarization transfer in a single analytical formula. An important conclusion from this study was that the polarization is proportional to the relaxation time T 1 of the bound substrate and dihydrogen (in the SABRE complex); soon after, this was confirmed experimentally …”

Fine-tuning the efficiency of para-hydrogen-induced hyperpolarization by rational N-heterocyclic carbene design

“…We also improve the SABRE polarization of the 13 C nuclei in doubly labelled 13 C 2 -diphenylpyridazine ( G ), that has been shown to sustain a singlet state with a lifetime of ca. 2 min 32 , though other substrates have been shown to be amenable to 13 C SABRE 25 , 55 – 57 . Polarization transfer using 1 (5 mM) and G (20 mM) in methanol- d 4 at ~0.5 G resulted in a 2.6% polarization level (Fig.…”

Hyperpolarising Pyruvate through Signal Amplification by Reversible Exchange (SABRE)

“…Upon transfer into a9 .4 Tm agnet, strongly hyperpolarised 13 Cresonances corresponding to free pyruvate were observed. [10,25] In contrast to the situation with 1 and 2,i sotopomer 3 is predicted to give as inglet-based response after polarisation transfer between 0Gand 1kG (Figure 3a,b). An overall 13 C polarisation level of about 1% results for asample containing [Ir(Cl)(COD)(IMes)] (5 mm), DMSO,and the corresponding pyruvate isotopologue in a1:8:5 ratio after shaking with 3bar of p-H 2 for 20 s. When as imilar sample containing 2 was examined, the corresponding maximum polarisation level proved to be 0.6 %when transfer took place at AE 3mG.…”