Single-scan measurements of nuclear spin singlet order decay rates.

Giulia Melchiorre,Giuseppe Pileio,Jean-Nicolas Dumez,Ciara Nelder,Lynda J Brown

doi:10.1039/d1cp00807b

Abstract

Measurements of singlet spin order decay rates are time consuming due to the long-lived nature of this form of order and the typical pseudo-2D mode of acquisition. Additionally, this acquisition modality is not ideal for experiments run on hyperpolarized order because of the single-shot nature of hyperpolarization techniques. We present a methodology based on spatial encoding that not only significantly reduces the duration of these experiments but also confers compatibility using spin hyperpolarization techniques. The method condenses in a single shot the variable delay array used to measure decay rates in conventional pseudo-2D relaxation experiments. This results in a substantial time saving factor and, more importantly, makes the experiment compatible with hyperpolarization techniques since only a single hyperpolarized sample is required. Furthermore, the presented method, besides offering savings on time and costs, avoids reproducibility concerns associated with repetition in the hyperpolarization procedure. The method accelerates the measurement and characterization of singlet order decay times, and, when coupled with hyperpolarization techniques, can facilitate the quest for systems with very long decay times.

Highlights

We present a methodology based on spatial encoding that significantly reduces the duration of these experiments and confers compatibility using spin hyperpolarization techniques
The method condenses in a single shot the variable delay array used to measure decay rates in conventional pseudo-2D relaxation experiments
Long-lived spin order is exploited as a vehicle to preserve spin hyperpolarization gained through techniques such as PHIP,[37] SABRE38 and dissolution–DNP.[39]

Summary

Introduction

NMR methodologies that exploit various aspects of long-lived nuclear spin singlet order – all groupable under the name singlet NMR – are under constant development.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17] The three main properties of this form of spin order – NMR silent, accessible on demand and long-lived – have found a variety of applications including: quantification, with enhanced sensitivity, of ligand binding;[18,19] measurements of very slow translational dynamics;[20,21,22,23,24,25] and their exploitation as molecular tags that can preserve information over a long time.[26,27,28,29,30,31,32,33,34,35,36] Long-lived spin order is exploited as a vehicle to preserve spin hyperpolarization gained through techniques such as PHIP,[37] SABRE38 and dissolution–DNP.[39]. We introduce a methodology that uses spatially selective long-lived spin order preparation techniques[23] to reduce the experimental time required to measure TS to a duration equivalent to the longest point in the variable delay array: T $ tnr. This procedure is valuable in further cutting down on experimental time (and associated costs) and, as the other existing methods, it would only require a single hyperpolarized sample reducing preparation time, costs and irreproducibility issues

Proposed methodology

Materials and methods

Findings

Long-lived Nuclear Spin Order