Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.

Among the methods to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, small-diameter NMR coils (microcoils) are promising tools to tackle the study of mass-limited samples. Alternatively, hyperpolarization schemes based on dynamic nuclear polarization techniques provide strong signal enhancements of the NMR target samples. Here we present a method to effortlessly perform photo-chemically induced dynamic nuclear polarization in microcoil setups to boost NMR signal detection down to sub-picomole detection limits in a 9.4T system (400 MHz ¹H Larmor frequency). This setup is unaffected by current major drawbacks such as the use of high-power light sources to attempt uniform irradiation of the sample, and accumulation of degraded photosensitizer in the detection region. The latter is overcome with flow conditions, which in turn open avenues for complex applications requiring rapid and efficient mixing that are not easily achievable on an NMR tube without resorting to complex hardware.