Ultrafast Laplace NMR to study metal–ligand interactions in reversible polarisation transfer from parahydrogen

Abstract

Laplace Nuclear Magnetic Resonance (NMR) can determine relaxation parameters and diffusion constants, giving valuable information about molecular structure and dynamics. Information about relaxation times (T1 and T2) and the self-diffusion...

Metal-Mediated Catalytic Polarization Transfer from para Hydrogen to 3,5-Dihalogenated Pyridines

“…Accordingly, single-shot hyperpolarized T 1 values were also measured for these samples (Figure c). Generally the values for both A and B , in either solvent, are shortened by the presence of the metal catalyst, and this effect is lessened when the substrate is present at a higher loading. − For example, the T 1 times extend to 170 and 262 s for the ortho and para sites, respectively of A when there is a 200-fold excess of it compared to 1 (Table S5). When the catalyst is present at 5 equiv relative to A , these T 1 times compress to just 9% and 24% of these values (Table S5).…”

“…Consequently, 6 A reflects a novel neutral SABRE polarization transfer catalyst. It is important to note that at these higher temperatures relatively facile H–D exchange between H 2 and methanol- d 4 , becomes evident, which complicates the appearance of the hydride ligand signals of 6 A and 7 A ; there is also evidence for deuteration of A . , …”

“…It is important to note that at these higher temperatures relatively facile H−D exchange between H 2 and methanol-d 4 , becomes evident, which complicates the appearance of the hydride ligand signals of 6 A and 7 A ; there is also evidence for deuteration of A. 33,34 The equilibrium position between 6 A and 7 A can be tipped to favor the exclusive formation of 6 A by changing the solvent to dichloromethane-d 2 . When pH 2 addition is monitored at 253 K in dichloromethane-d 2 , a much slower reaction ensues, with signals again observed for 3, 5 A and 6 A with relative PHIP signal intensities 1:0.45:5.3.…”

Hyperpolarised NMR to aid molecular profiling of electronic cigarette aerosols

“…6.5 mT (see ESI, Section S1.4 † ). 36 This field was selected as it has been reported optimal for most efficient SABRE polarisation transfer to 1 H sites within nicotine and similar N-heterocyclic targets. 5,37 After shaking, samples were rapidly inserted into a 9.4 T NMR spectrometer for collection of a single scan 1 H NMR spectrum.…”

Ultrafast transverse relaxation exchange NMR spectroscopy

“…Spatial encoding has been exploited in T 1 relaxation and diffusion experiments as well. [22][23][24][25][26][27][28][29][30][31] Lately, we have introduced the spatial encoding technique to many multidimensional relaxation and diffusion experiments, which enable one to correlate various LNMR parameters such as T 1 , T 2 and diffusion coefficient D. [30][31][32][33][34][35][36] The inverse Laplace transformation (ILT) of the data provides relaxation time or diffusion coefficient distribution. 37 Therefore, these methods are referred to as UF Laplace NMR (LNMR).…”