http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/ Molecules: You'd Better Learn to Live With Them Sat, 22 Nov 2008 06:13:56 +0000 http://wordpress.org/?v=2.0.2 http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2770 Thu, 03 Aug 2006 09:43:41 +0000 http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2770 You know, that's a really good question..! It was just one of the things I took for granted when I did my PhD. I worked with crown ethers and secondary dialkylammonium ions, and to thread one of the latter through the former, you need to use dibenzo[24]crown-8 or a similar derivative, the next lower homologue is 21-crown-7 and that's too small - making one with 23 atoms in the ring is a little more tricky as you lose the nice O-CH2-CH2-O repeat unit. I think there's a discussion of ring size in a Chem. Eur. J. paper from 1996, pages 709-728 (out of the Stoddart group). As for the smallest catenane, I think that prize goes to David Leigh (now Edinburgh) who interlocked two 26-membered rings (Angewandte 1995 I think...). That's ignoring some organometallic magnesium catenanes in which it is just the magnesium atom of a cyclic-dialkylmagnesium that sits inside a crown ether-type ring. There's also been plently of 'slippage' studies where different end-groups on molecular chains have been pulled through macrocycles in-computero... For a good general overview of the field, Wiley published a book by Jean-Pierre Sauvage on molecular catenanes, rotaxanes and knots... very expensive I imagine... You know, that’s a really good question..! It was just one of the things I took for granted when I did my PhD. I worked with crown ethers and secondary dialkylammonium ions, and to thread one of the latter through the former, you need to use dibenzo[24]crown-8 or a similar derivative, the next lower homologue is 21-crown-7 and that’s too small - making one with 23 atoms in the ring is a little more tricky as you lose the nice O-CH2-CH2-O repeat unit. I think there’s a discussion of ring size in a Chem. Eur. J. paper from 1996, pages 709-728 (out of the Stoddart group). As for the smallest catenane, I think that prize goes to David Leigh (now Edinburgh) who interlocked two 26-membered rings (Angewandte 1995 I think…). That’s ignoring some organometallic magnesium catenanes in which it is just the magnesium atom of a cyclic-dialkylmagnesium that sits inside a crown ether-type ring. There’s also been plently of ’slippage’ studies where different end-groups on molecular chains have been pulled through macrocycles in-computero… For a good general overview of the field, Wiley published a book by Jean-Pierre Sauvage on molecular catenanes, rotaxanes and knots… very expensive I imagine…

]]> http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2768 Thu, 03 Aug 2006 02:17:25 +0000 http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2768 Ah, I was worried I'd get a comment like that. I had no idea what size of things actually could be made into catenanes. Is this an experimental thing, or has someone worked it out mathematically? Thanks for the correction! Ah, I was worried I’d get a comment like that. I had no idea what size of things actually could be made into catenanes. Is this an experimental thing, or has someone worked it out mathematically? Thanks for the correction!

]]> http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2767 Wed, 02 Aug 2006 08:58:25 +0000 http://www.moleculeoftheday.com/2006/07/31/catenane-trickier-than-they-look/#comment-2767 The catenane shown above is impossible, you need a ring with at least 24 atoms in it before you can thread another molecular chain through it... The catenane shown above is impossible, you need a ring with at least 24 atoms in it before you can thread another molecular chain through it…

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