Solid-state NMR joins IUCr

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  • Published: Nov 20, 2014
  • Author: Professor Robin Harris, University of Durham
  • Channels: NMR Knowledge Base / MRI Spectroscopy
thumbnail image: Solid-state NMR joins IUCr

Vanadium atoms (blue) have unusually large thermal vibrations that stabilize the metallic state of a vanadium dioxide crystal. Red depicts oxygen atoms. Image credit: Oak Ridge National Laboratory

In this International Year of Crystallography, NMR has at last established its own Commission within The International Union of Crystallography, joining 22 other commissions on a whole range of crystallographic subjects. Its incorporation into IUCr was approved at the Montreal meeting in August 2014. The Commission’s brief includes methods related to NMR (such as ESR/EPR). A web site is being developed at www.iucr.org/iucr/commissions/nmr-crystallography, to which readers are directed for further information as the work of the commission develops. The current commission membership consists of Francis Taulelle (as Chair), Robin Harris and Manish Mehta (joint secretaries), Tatyana Polenova, Marek Potrzebowski and Rod Wasylishen, but others will be added in the coming months.

Solid-state NMR specialists will know that this development is not before time. NMR was recognised as of value to crystallography even as early as 1949 when a paper by Gutowsky et al. stated that “The development of experimental methods for observing nuclear magnetism has provided a means of investigating certain aspects of molecular & crystal structure”. In fact, even before that time, an article by Pake described using solid-state NMR to determine the distance between protons in water of crystallisation of gypsum as 1.58 Å, a result which could not be obtained by X-ray diffraction methods at the time. Even now, of course, X-ray diffraction determines the centre of electron density around a hydrogen atom rather than the position of the nucleus (and these points differ substantially).

Carbon-13 CPMAS spectrum and crystal structure of terbutaline sulfate.


However, whilst crystallographic results from NMR became common after the CPMAS suite of techniques was developed in the 1970s, diffraction crystallographers largely ignored the developments. Indeed, as late as 2006 a referee for an NMR article which Lyndon Emsley and colleagues submitted to JACS, remarked “Crystallography specifically applies to diffraction of electromagnetic radiation”! Fortunately, attitudes have now changed - hence the new IUCr Commission. It is hoped that there will be increasing interaction between NMR and diffraction practitioners. The two techniques are largely complementary. NMR can address issues of disorder and dynamics within crystals inaccessible by diffraction since the timescales appropriate to the two methodologies are different. The length scales also differ – NMR responds to the local environment of atoms, whereas diffraction techniques rely on long-range order. Thus NMR is superior to diffraction in determining the chemical structures of amorphous and heterogeneous materials. Moreover, recent developments of computational methods such as CASTEP mean that NMR data can be used in a process of refining structures from diffraction results. NMR also provides information which can enable structure determination from powder diffraction data. For all these reasons, diffraction and NMR go hand-in-hand for structure determination in the future. The existence of the new Commission within IUCr should promote the combined use of the two techniques.


Professor Robin Harris
University of Durham, UK
November 2014

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