Editorial pubs.acs.org/accounts
Transmission Electron Microscopy for Chemists Guest Editorial for the Accounts of Chemical Research special issue on “Direct Visualization of Chemical and SelfAssembly Processes with Transmission Electron Microscopy”.
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ne hundred years after the modern framework of chemistry was established, chemistry in the 21st century is venturing beyond its classical disciplinary borders, and the analytical methods are also evolving. Among them, transmission electron microscopy (TEM) is a newcomer to the range of standard analytical tools, after NMR in the 1970s and X-ray crystallography in the 1990s. Like NMR and X-ray, we expect that TEM technology will soon become a mainstream method for the analysis of (bio)chemical and self-assembly processes the central theme of this special issue. NMR has become popular among chemists due to its ability to quickly reveal atom connectivity (e.g., H−C−C−H coupling) and the mutual proximities of the atoms. X-ray crystallography is now a part of everyday research, as it quickly tells us the three-dimensional structure of a (macro)molecule often just after an overnight measurement. Spectroscopy and crystallographic analyses like many other analytical methods rely on data averaged over molecules and over time. Therefore, the quality of the information rapidly deteriorates when the specimen is a mixture of different compounds or contains molecules and molecular assemblies that change their structure over time. High-resolution TEM is unique in its capacity in that it can directly obtain images of objects at a given time, down to individual atoms. In addition, it has a capacity to perform spectroscopic and diffraction analyses revealing their chemical composition and electronic structure. TEM imaging of molecules may not need any periodicity in the spatial disposition of atoms under study because the image comes from interference caused by the atoms under study. The time resolution is potentially high because the speed of electrons used for TEM is close to that of light. This means that molecules, molecular assemblies, or solids that do not show atomic periodicity or are not pure in the usual chemical sense may be studied at the atomic or molecular level with high resolution TEM. One can therefore observe, in situ and in realtime, a set of different nanometer-sized objects of different sizes and structures at atomic resolution. To study dynamic events including reactions and assembly processes, a series of snapshots can be recorded, hence constructing movies even with three-dimensional information and at atomic resolution. Seeing is believing: The atomic resolution image of a molecule or an atom or a molecular assembly produced by TEM is the most direct structural information among those given by any other known analytical method. The image is so straightforward that it will also contribute to science education at large, as it happened 350 years ago for optical microscopy. In 1665, Robert Hooke proudly illustrated his (optical) microscope and the miniature world under it (Figure 1) including a flea and a plant “cell” in his celebrated book, Micrographia: or Some Phy∫ iological De∫ criptions of Minute Bodies Made by © 2017 American Chemical Society
Figure 1. Illustrations in Micrographia (London, the Royal Society, 1665) published by Robert Hooke. Images from https://en.wikipedia. org/wiki/Micrographia#/media/File:HookeFlea01.jpg, and https:// en.wikipedia.org/wiki/Micrographia#/media/File:Hooke-microscope. png.
Magnif ying Glasses. With Observations and Inquiries Thereupon, and declared: The truth is, the Science of Nature has been already too long made only a work of the Brain and the Fancy: It is now high time that it should return to the plainness and soundness of Observations on material and obvious things. Recent technical advances in TEM instrumentation including aberration control, phase contrast imaging, the use of fast and sensitive detectors, three-dimensional tomography, in situ liquid cell imaging and environment control, cryogenic fixation, and data processing software have provided new possibilities in bridging electron microscopy and chemistry, biology, and materials science. It has opened exciting new fields of research spanning from fundamental science to development of products of commercial interest, illustrated in this special issue by atomic resolution imaging of organic molecules in action, hierarchical ordering of inorganic nanoparticles, interface control, biomineralization, structural studies of polymers, and visualization of local electromagnetic field structures. This issue of Accounts of Chemical Research highlights the most recent achievements by researchers who are actively trying to bridge electron microscopy and chemistry so as to further develop the interface between the two fields of research.
Eiichi Nakamura, Guest Editor The University of Tokyo
Nico A. J. M. Sommerdijk, Guest Editor Eindhoven University of Technology
Haimei Zheng, Guest Editor Lawrence Berkeley National Laboratory Received: June 23, 2017 Published: August 15, 2017 1795
DOI: 10.1021/acs.accounts.7b00318 Acc. Chem. Res. 2017, 50, 1795−1796
Accounts of Chemical Research
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Editorial
AUTHOR INFORMATION
ORCID
Eiichi Nakamura: 0000-0002-4192-1741 Nico A. J. M. Sommerdijk: 0000-0002-8956-195X Haimei Zheng: 0000-0003-3813-4170 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.
1796
DOI: 10.1021/acs.accounts.7b00318 Acc. Chem. Res. 2017, 50, 1795−1796
