Still shimming or already measuring?--Quantitative reaction monitoring for small molecules on the sub minute timescale by NMR

A one-shot double-slice selection NMR method for biphasic systems

We propose a new and robust one-shot double-slice selection experiment to detect 1H NMR signals of biphasic systems simultaneously. The resultant spectrum contains opposite-phased peaks representing the chemical species from the two phases, respectively.

Mechanistic analysis by NMR spectroscopy: A users guide

A 'principles and practice' tutorial-style review of the application of solution-phase NMR in the analysis of the mechanisms of homogeneous organic and organometallic reactions and processes. This review of 345 references summarises why solution-phase NMR spectroscopy is uniquely effective in such studies, allowing non-destructive, quantitative analysis of a wide range of nuclei common to organic and organometallic reactions, providing exquisite structural detail, and using instrumentation that is routinely available in most chemistry research facilities. The review is in two parts. The first comprises an introduction to general techniques and equipment, and guidelines for their selection and application. Topics include practical aspects of the reaction itself, reaction monitoring techniques, NMR data acquisition and processing, analysis of temporal concentration data, NMR titrations, DOSY, and the use of isotopes. The second part comprises a series of 15 Case Studies, each selected to illustrate specific techniques and approaches discussed in the first part, including in situ NMR (^1/2H, ^10/11B, ¹³C, ¹⁵N, ¹⁹F, ²⁹Si, ³¹P), kinetic and equilibrium isotope effects, isotope entrainment, isotope shifts, isotopes at natural abundance, scalar coupling, kinetic analysis (VTNA, RPKA, simulation, steady-state), stopped-flow NMR, flow NMR, rapid injection NMR, pure shift NMR, dynamic nuclear polarisation, ¹H/¹⁹F DOSY NMR, and in situ illumination NMR.

MRI and localised NMR spectroscopy of sessile droplets on hydrophilic, hydrophobic and superhydrophobic surfaces - Examination of the chemical composition during evaporation

Evaporation of droplets is a process important in many different areas of science, technology and also everyday life. The understanding of droplet evaporation of homogeneous and heterogeneous substance mixtures is important, for example, to explain the formation of coffee stains or to optimize the results in offset printing. For a detailed understanding of the evaporation of complex mixtures from structured surfaces, such as inks used in offset printing, a time-resolved analysis of the droplet composition is essential. Measurement of (local) concentrations may deepen the understanding of wetting phenomena and their connection with transport phenomena. Therefore, we demonstrate in this paper that magnetic resonance methods can be used to (a) image sessile droplets on structured surfaces and (b) investigate their composition in a time-resolved manner. First it is shown that water droplets on superhydrophobic, hydrophobic and hydrophilic surfaces, despite the large liquid/gas interface, can be imaged well and without interfering artefacts using RARE. Further, the signals are examined in localised PRESS NMR spectra with respect to line shape and quantifiability. Finally, it is demonstrated that non-localised NMR spectra can be used to track the droplet composition during evaporation.

Monitoring fast chemical processes by reaction-interrupted excitation transfer (ExTra) NMR spectroscopy

ExTra NMR utilises selectively inverted magnetisation for in situ monitoring of fast chemical processes.

Spatial encoding and spatial selection methods in high-resolution NMR spectroscopy

A family of high-resolution NMR methods share the common concept of acquiring in parallel different sub-experiments in different spatial regions of the NMR tube. These spatial encoding and spatial selection methods were for the most part introduced independently from each other and serve different purposes, but they share common ingredients, often derived from magnetic resonance imaging, and they all benefit from a greatly improved time-efficiency. This review article provides a description of several spatial encoding and spatial selection methods, including single-scan multidimensional experiments (ultrafast 2D NMR, DOSY, Z spectroscopy, inversion recovery and Laplace NMR), pure shift and selective refocusing experiments (including Zangger-Sterk decoupling, G-SERF and PSYCHE), a Z filter, and fast-pulsing slice-selective experiments. Some key elements for spatial parallelisation are introduced and when possible a common framework is used for the analysis of each method. Sensitivity considerations are discussed, and a selection of applications is analysed to illustrate which questions can be answered thanks to spatial encoding and spatial selection methods, and discuss the perspectives for future developments and applications.

NMR analysis of weak molecular interactions using slice-selective experiments via study of concentration gradients in agar gels

Weak molecular interactions can be localized and quantified using a single NMR experiment analysing concentration gradients generated in agar gels.