CiQUS and IBM research scientists first to image short-lived molecules
The technique has broad applications for on-surface chemistry and electronics, including the preparation of graphene nanoribbons and novel single-molecule devices. There are trillions of molecules in the universe and some of them are stable enough to be isolated and characterized, but many others are so short lived that they can only be proposed indirectly via chemical reactions or spectroscopic methods. One such species are arynes, which were first suggested in 1902, and since then have been used as intermediates or building blocks in the synthesis of a variety of compounds for applications including medicine, organic electronics and molecular materials. The challenge with these particular molecules is that they only exist for several milliseconds making them extremely challenging to image, until now. Today the peer-reviewed journal Nature Chemistry (On-surface generation and imaging of arynes by atomic force microscopy, DOI: 10.1038/nchem.2300) has published the imaging of a single aryne molecule for the first time. This work is the result of a joint effort made by CiQUS researchers in Santiago, who are experts in aryne chemistry, and the IBM team in Zürich, who developed new atomic resolution microscopic techniques. 'Arynes are discussed in almost every undergraduate course on organic chemistry around the world. Therefore, it’s kind of relief to find the final confirmation that these molecules truly exist,' said Professor Diego Peña, a chemist at the University of Santiago de Compostela. 'I look forward to seeing new chemical challenges solved by the combination of organic synthesis and AFM.' After the preparation of the key aryne precursor by CiQUS, IBM scientists used the sharp tip of a Scanning Tunneling Microscope (STM) to generate individual aryne molecules from precursor molecules by atomic manipulation. The experiments were performed on films of sodium chloride, at temperatures near absolute zero, to stabilize the aryne. Once the molecules were isolated the team used Atomic Force Microscopy (AFM) to measure the tiny forces between the tip, which is terminated with a single carbon monoxide molecule, and the sample to image the aryne’s molecular structure. The resulting image was so clear that the scientists could study their chemical nature based on the minute differences between individual bonds. 'The IBM team developed several state-of-the-art techniques since 2009 which made this achievement possible,' said Dr. Niko Pavliček, a physicist at IBM Research. 'For this study it was absolutely essential to pick an insulating film on which the molecules were adsorbed and to deliberately choose the atomic tip-terminations to probe them. We hope this technique will have profound effects on the future of chemistry and electronics.' This work is a result of the large European project called PAMS (Planar Atomic and Molecular Scale Devices). PAMS’ main objective is to develop and investigate novel electronic devices of nanometric-scale size. Part of this research is funded by a European Research Council (ERC) Advanced Grant awarded to IBM scientist Gerhard Meyer, who is also a co-author of the paper. These prestigious grants support 'the very best researchers working at the frontiers of knowledge' in Europe. IBM Research and CiQUS have previously collaborated and published papers on differentiating the chemical bonds (Science, 2012, 337, 1326) in individual molecules and imaging high quality nanographenes (Angew. Chem. Int. Ed., 2014, 53, 9004) generated from easily available organic compounds.
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Switzerland, Spain