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The Mechanisms of Making Molecules to Order
Author(s) -
Brown Christopher L.,
Philp Douglas,
Spencer Neil,
Fraser Stoddart J.
Publication year - 1992
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199200009
Subject(s) - catenane , chemistry , cyclophane , benzene , molecule , stereochemistry , bipyridine , crystallography , organic chemistry , crystal structure
The mechanisms of formation of a [2]catenane and one of its molecular components have been investigated. While the synthesis of the tetracationic cyclophane, [BBIPYBIXYCY] 4+ from bipyridine (BP) and 1,4‐bis(bromomethyl)benzene (BBB) , directed by the template, 1,5–bis[2(2–hydroxyethoxy)ethoxy]naphthalene (1/5BHEEN) becomes less efficient (23 to 5%) under ultra‐high pressure reaction conditions (12 kbars), the self‐assembly of {[2]‐[BPP34C10]‐[BBIPYBIXYCY] catenane} 4+ from BP and BBB in the presence of BPP34C10 can be achieved with increased efficiency (18 to 42%) at 12 kbars. This difference in the trends of the yields can be ascribed to the enhanced templating action of BPP34C10 relative to that of 1/5BHEEN when two moles of BP and two moles of BBB are being employed to construct the tetracationic cyclophane. The self‐assembly of the [2]catenane from BP, BBB , and BPP34C10 has been followed by 1 H NMR spectroscopy in D 7 ‐DMF solution. On the basis of this spectroscopic evidence and supporting chemical data, the formation of {[2]‐[BPP34C10]‐[BBIPYBIXYCY] catenane} 4+ from two moles of BP , two moles of BBB , and one mole of BPP34C10 is believed to proceed via the monoquatemary intermediate, [MBXYBIPY] + , which has not been isolated, and the dicationic species, [BBIPYXY] 2+ , which has been isolated and shown to be an intermediate in the self‐assembly process leading to the [2]catenane, presumably via the [BXYBBIPYXY] 3+ trication — the final intermediate which again has not been isolated.