Nuclear Magnetic Resonance (NMR) Spectroscopy
Nuclear Magnetic Resonance (NMR) spectroscopy provides detailed information about the structure, dynamics and interactions of molecules. NMR spectroscopy has a wide variety of applications in the study of molecules and molecular processes across many disciplines including chemistry, biochemistry, medicine, pharmacology, physics, engineering, plant biology and soil science.
What can NMR spectroscopy do?
NMR spectroscopy is used to determine the identity and structure of molecules, from small (e.g. caffeine) to large (e.g. proteins, polymers) and everything in between. It can also be used to determine quantities and concentration, dynamic behaviour, and investigate interactions and reactions between molecules.
NMR spectroscopy relies on a fundamental property of atomic nuclei in which the nuclear magnetic moment (or ‘spin’) interacts with a strong external magnetic field. When we use electromagnetic radiation of the correct ‘resonant’ frequency, we can generate a signal from these spins. In this way, spectra are produced which display a characteristic frequency (or ‘chemical shift’) output of the species under investigation, which provides information about the chemical environment of a given atom in a molecule. NMR spectroscopy is also inherently quantitative, whereby the intensity of the signals observed is directly proportional to the quantity or concentration of the species in the sample and can also be used to investigate dynamics or rates of chemical processes.
What about EPR spectroscopy?
The laboratory is also equipped with a benchtop EPR spectrometer. Electron Paramagnetic Resonance (EPR) (or “Electron Spin Resonance”, ESR) spectroscopy works in a very similar manner to NMR, except it focuses on samples that have an unpaired electron, such as organic radicals, and some transition metal ions. EPR spectroscopy can be used to study the structure, dynamics and reactivity of molecules and materials with these unpaired electrons. Our lab is equipped to perform these measurements on solids, solutions and biological samples, with control over a wide range of temperatures (77 K, and 93 – 473 K). Irradiation and electrochemical experiments within the spectrometer are also supported, and an automated goniometer allows the control of the sample orientation within the cavity when required.
Our techniques
One-dimensional spectra
We are able to perform all manner of 1D NMR spectroscopy experiments on a wide range of elements. The laboratory is well equipped to perform routine work (e.g. 1H, 13C, 19F, 31P etc.), all of our instruments have sample changers to allow data acquisition in an automated manner, and we can perform experiments at variable temperatures. Quantitative NMR (qNMR) on a wide variety of samples can be performed, either by the user, or as a service.
In addition, we have extensive experience with less common and less abundant isotopes (e.g. 2H, 7Li, 11B, 29Si, 77Se, 103Rh, 195Pt etc.) and will be happy to help you with your multinuclear NMR needs.
Multidimensional studies
Multidimensional NMR spectroscopy experiments have transformed the technique, providing data rich in information relating to structure, dynamics and reactivity. The NMR laboratory at UWA is well equipped to perform these experiments on a variety of samples, from small molecule to biomolecular systems. Examples are the powerful but relatively routine measurement of molecular bonding arrangements with COSY, HSQC and HMBC techniques, 3D structure with NOESY and ROESY, and even molecular size information through the measurement of diffusion coefficients (e.g. DOSY NMR).
Other less common but equally powerful methods are available, please get in touch with the team for further details.
Solid state NMR (MAS)
Solid samples typically produce very broad NMR spectra due to significant dipolar broadening, but if a powdered sample is packed into a rotor and spun at high speed at the ‘magic angle’ of 54.7° a significant increase in the resolution of the spectrum can be obtained. This Magic Angle Spinning (MAS) NMR spectroscopy is the basis for analysing a wide range of solid materials in atomic detail, such as synthetic polymers and plastics, wood, bio- and synthetic materials, catalysts, minerals and soils. These experiments can be performed on a wide range of elements of interest, under a range of temperatures (ca. -50 °C to + 150 °C), and soon with the ability to pressurise the samples up to ca. 300 bar!
FAQ
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Who can use the equipment?
The lab is open-access and available to any researchers with an interest in obtaining NMR or EPR spectra. Most users operate the instruments themselves, after registration and training, but samples can be submitted for analysis by CMCA staff. Industry users are also able to access the facility in the same way.
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How do I get started?
Get in touch with us first to discuss your project needs [email protected].
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What samples can you analyse?
In principle, any sample that contains appreciable (~ µg - mg) quantities of an NMR active isotope is amenable to analysis. Samples can be observed in solution or in the solid-state.
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Can you help with data analysis?
Yes, part of your training involves the analysis of your data, which should allow you to progress your research aims. Analysis and reporting of your results can be provided by CMCA staff if required.
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How much sample do I need to submit?
For solution-state NMR spectroscopy, typically we work with milligram quantities of material, but smaller quantities can be handled, depending on the application. For solid-state NMR, we require roughly 100 mg of material to fill the rotors.
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How should I prepare my sample?
- Solution-state NMR:
- Samples can be provided as-is or dissolved in (usually) a deuterated solvent. Solvent volumes can go as low as 50 µL, but routine work is conducted on ~ 600 µL solution volumes.
- Solid-state NMR:
- Samples for MAS analysis should be provided in a powdered form.
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Where are the samples prepared?
Limited sample preparation facilities are available on-site, but most samples are prepared in the researcher’s own laboratory prior to arrival.
Our instruments
- Bruker Avance IIIHD 600MHz NMR spectrometer
- Bruker Avance IIIHD 500MHz NMR spectrometer
- Bruker Avance NEO 400 MHz NMR spectrometer
- Bruker Avance NEO 400 MHZ NMR spectrometer for solids
- Bruker ESR5000 Benchtop ESR
Platform expert
Dr Gareth Nealon
NMR Platform Leader, Centre for Microscopy, Characterisation and Analysis