Modification of an NMR probe for monitoring of photoreactions

Paululat, Thomas; Rabe, Markus; Berdnikova, Daria V.

doi:10.1016/j.jmr.2021.106990

Cited by 9 publications

(16 citation statements)

References 14 publications

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“…In situ illumination of samples opens up a realm of potential light-sensitive experimental systems which may be studied by high-resolution NMR spectroscopy, one of the most powerful analytical techniques. Although a range of illumination strategies have been previously suggested, including guiding external light sources with optical fibres 29 , 30 , 47 , or modifying the NMR probe itself 20 , 21 , 27 , 34 , these solutions are generally cumbersome to use at higher throughputs, or require customised probes. Here, we present a new universal and convenient approach to illuminating NMR samples in situ with the LED-based NMRtorch device, which should be compatible with any typical NMR probehead, including cryoprobes.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, the rapid development and availability of inexpensive and powerful light-emitting diodes (LEDs) with a wide choice of emission wavelengths has led to their increasing use as light sources in photo-NMR 12 , 13 , 30 – 33 . Although NMR probe modifications to incorporate LED illumination directly inside the probehead have been suggested 27 , 34 , optical fibres (either alone or inside a coaxial insert) are still typically used to guide light from the LED positioned outside the NMR spectrometer to the NMR sample inside the magnet. However, these setups also suffer from the same disadvantages inherent to the LASER-fibre optic system, with the additional difficulty of coupling poorly collimated light from an LED into a thin optical fibre, leading to significant light intensity losses 12 , 30 .…”

Section: Introductionmentioning

confidence: 99%

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Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics

Bramham

Golovanov

2022

Commun Chem

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In situ illumination of liquid-state nuclear magnetic resonance (NMR) samples makes it possible for a wide range of light-dependent chemical and biological phenomena to be studied by the powerful analytical technique. However, the position of an NMR sample deep within the bore of the spectrometer magnet renders such illumination challenging. Here, we demonstrate the working principles of a sample illumination device (NMRtorch) where a lighthead containing an LED array is positioned directly at the top of an NMRtorch tube which is inserted into the NMR spectrometer. The wall of the tube itself acts as a light guide, illuminating the sample from the outside. We explore how this new setup performs in a number of photo-NMR applications, including photoisomerisation and photo-chemically induced dynamic nuclear polarisation (photo-CIDNP), and demonstrate the potential for ultraviolet (UV) degradation studies with continuous online NMR assessment. This setup enables users of any typical liquid-state spectrometer to easily perform in situ photo-NMR experiments, using a wide range of wavelengths.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics

Bramham

Golovanov

2022

Commun Chem

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“…Equipment : NMR spectra: JEOL ECZ 500 and Varian VNMR−S 600 spectrometers in DMSO‐ d 6 ( δ H =2.50 ppm, δ C =39.5 ppm) at 25 °C. Real‐time NMR spectroscopy experiments with in situ irradiation (Varian VNMR‐S 600) were performed using a home‐made setup providing direct irradiation of a sample inside the spectrometer [14] . Mass spectra (ESI): Finnigan LCQ Deca ( U =6 kV; working gas: He; auxiliary gas: N 2 ; temperature of the capillary: 200 °C).…”

Section: Methodsmentioning

confidence: 99%

Fused Bis(hemi‐indigo): Broad‐Range Wavelength‐Independent Photoswitches

Berdnikova

Kriesche

Paululat

et al. 2022

Chemistry A European J

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Wavelength‐independent conversion of organic photoswitches in the photostationary state is a rare phenomenon that opens up a way for many practical applications. In this work, three fused bis(hemi‐indigo) derivatives with different substitution patterns were synthesized and their photoswitching was investigated by optical spectroscopy, real‐time NMR spectroscopy and TD‐DFT calculations. We disclosed that the Z‐E photoisomerization of the meta‐bis(hemi‐indigo) derivative was remarkably independent of the irradiation wavelength from UV up to yellow light. The wavelength‐independent forward photoswitching together with the inhibited backward photoisomerization, high thermal stability of the photoinduced isomers as well as significant overlap between the photoswitch absorption and the solar spectrum allows to suggest bis(hemi‐indigo) derivatives as promising candidates for molecular solar thermal energy storage (MOST) systems.

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“…To conclude the introduction, in the present work, we focus on the investigation of photoreactions in the mixture of anthracenes. To do this, we employ 1 H NMR spectroscopy, which is being more and more often employed in the field of photochemistry and reaction monitoring [43][44][45][46][47]. We demonstrate that a simple NMR approach can easily deliver data which enables us to obtain insights into the kinetics of the photoreactivity between varying anthracenes.…”

Section: Introductionmentioning

confidence: 99%

Photoreactivity of an Exemplary Anthracene Mixture Revealed by NMR Studies, including a Kinetic Approach

et al. 2021

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Anthracenes are an important class of acenes. They are being utilized more and more often in chemistry and materials sciences, due to their unique rigid molecular structure and photoreactivity. In particular, photodimerization can be harnessed for the fabrication of novel photoresponsive materials. Photodimerization between the same anthracenes have been investigated and utilized in various fields, while reactions between varying anthracenes have barely been investigated. Here, Nuclear Magnetic Resonance (NMR) spectroscopy is employed for the investigation of the photodimerization of two exemplary anthracenes: anthracene (A) and 9-bromoanthracene (B), in the solutions with only A or B, and in the mixture of A and B. Estimated k values, derived from the presented kinetic model, showed that the dimerization of A was 10 times faster in comparison with B when compounds were investigated in separate samples, and 2 times faster when compounds were prepared in the mixture. Notably, the photoreaction in the mixture, apart from AA and BB, additionally yielded a large amount of the AB mixdimer. Another important advantage of investigating a mixture with different anthracenes is the ability to estimate the relative reactivity for all the reactions under the same experimental conditions. This results in a better understanding of the photodimerization processes. Thus, the rational photofabrication of mix-anthracene-based materials can be facilitated, which is of crucial importance in the field of polymer and material sciences.

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Modification of an NMR probe for monitoring of photoreactions

Cited by 9 publications

References 14 publications

Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics

Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics

Fused Bis(hemi‐indigo): Broad‐Range Wavelength‐Independent Photoswitches

Photoreactivity of an Exemplary Anthracene Mixture Revealed by NMR Studies, including a Kinetic Approach

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