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 01.10.2009   Карта сайта     Language По-русски По-английски
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01.10.2009

Nature 461, 633-635 (1 October 2009) | doi:10.1038/nature08326; Received 7 April 2009; Accepted 23 July 2009



X-ray observation of a transient hemiaminal trapped in a porous network


Takehide Kawamichi1, Tsuyoshi Haneda1, Masaki Kawano1,3 & Makoto Fujita1,2




  1. Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

  2. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

  3. Present address: Division of Advanced Materials Science, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784, South Korea.


Correspondence to: Masaki Kawano1,3Makoto Fujita1,2 Correspondence and requests for materials should be addressed to M.K. (Email: mkawano@postech.ac.kr) or M.F. (Email: mfujita@appchem.t.u-tokyo.ac.jp).





X-ray crystallography is the method of choice for the direct structural analysis of crystalline compounds1. Extending its use to the in situ mapping of chemical transformations could provide valuable insights, as illustrated by time-resolved X-ray crystallography studies2, 3; however, the transient nature of unstable reaction intermediates often poses a significant challenge. It has recently been demonstrated that standard chemical reactions can occur within the pores of porous coordination networks4, 5, 6 and that the robust crystallinity of these networks facilitates in situ X-ray analysis of the adducts and products7, 8, 9, 10, 11. Here we show that such systems even enable X-ray observations of reaction intermediates that are usually transient and non-isolable. Our proof-of-concept demonstration examines the simple and ubiquitous reaction between an amine and an aldehyde, which normally form a very short-lived hemiaminal that then yields the Schiff-base product. The mechanism of this reaction has been exhaustively examined, but the hemiaminal intermediate has only rarely been observed12, 13, 14, 15, 16. We first determine the structure of a porous network with an aromatic amine embedded in it, then diffuse an aldehyde substrate into the material to transform the amine into a hemiaminal intermediate that is kinetically trapped and thus amenable to X-ray analysis, and finally raise the temperature of the system to obtain the imine product and determine its structure. These results establish that porous network materials provide a means of obtaining sequential X-ray-based snapshots of the structural transformations that occur during chemical reactions.



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  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

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