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Photoinduced formation of a cryptand from a coronand: an unexpected switch in cation binding affinity

Photoinduced formation of a cryptand from a coronand: an unexpected switch in cation binding affinity
Photoinduced formation of a cryptand from a coronand: an unexpected switch in cation binding affinity
Aza-crown ethers 2 and 3 with anthracene-containing pendant arms have been synthesised and characterised. Both compounds bind Group 1 metal cations in solution, forming complexes of 1:1 stoichiometry. The properties of compound 2 and its complexes have been studied by a range of techniques,. including NMR, UV and fluorescence spectroscopy and X-ray crystallography. The pendant arms can adopt either a cis or a trans geometry, the cis geometry favoured with larger cations. The geometry of the complex affects the fluorescence properties of the system, with larger cations giving higher excimer/monomer ratios. Upon irradiation ? > 300 nm, coronand 2 forms the cryptand 5 through a reversible intramolecular [4?+4?] cycloaddition reaction. The rates of the forward and reverse reactions of this photochromic process are cation dependent; in particular the rate of the thermal reverse reaction is decreased by smaller cations and increased by larger cations, especially Rb+. The metal binding constants in methanol for 2 and 5 have been determined, revealing that the cryptand 5 binds Na+ and Rb+ more weakly than crown ether 2 by over two orders of magnitude.
crown compounds, host-guest systems, molecular devices, photochromism, photoswitches
0947-6539
3331-3342
McSkimming, Gordon
c3907894-bb45-443d-bfb5-112a538f669b
Tucker, James H. R.
f4dcdb2e-03fb-4b22-8af5-11592e4f6684
Bouas-Laurent, Henri
44881bee-40db-4d7a-a269-5075504c8ca5
Desvergne, Jean-Pierre
4e2958c3-aa04-42f4-ad31-02295cd67697
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Light, Mark E.
cf57314e-6856-491b-a8d2-2dffc452e161
McSkimming, Gordon
c3907894-bb45-443d-bfb5-112a538f669b
Tucker, James H. R.
f4dcdb2e-03fb-4b22-8af5-11592e4f6684
Bouas-Laurent, Henri
44881bee-40db-4d7a-a269-5075504c8ca5
Desvergne, Jean-Pierre
4e2958c3-aa04-42f4-ad31-02295cd67697
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Light, Mark E.
cf57314e-6856-491b-a8d2-2dffc452e161

McSkimming, Gordon, Tucker, James H. R., Bouas-Laurent, Henri, Desvergne, Jean-Pierre, Coles, Simon J., Hursthouse, Michael B. and Light, Mark E. (2002) Photoinduced formation of a cryptand from a coronand: an unexpected switch in cation binding affinity. Chemistry - A European Journal, 8 (15), 3331-3342. (doi:10.1002/1521-3765(20020802)8:15<3331::AID-CHEM3331>3.0.CO;2-C).

Record type: Article

Abstract

Aza-crown ethers 2 and 3 with anthracene-containing pendant arms have been synthesised and characterised. Both compounds bind Group 1 metal cations in solution, forming complexes of 1:1 stoichiometry. The properties of compound 2 and its complexes have been studied by a range of techniques,. including NMR, UV and fluorescence spectroscopy and X-ray crystallography. The pendant arms can adopt either a cis or a trans geometry, the cis geometry favoured with larger cations. The geometry of the complex affects the fluorescence properties of the system, with larger cations giving higher excimer/monomer ratios. Upon irradiation ? > 300 nm, coronand 2 forms the cryptand 5 through a reversible intramolecular [4?+4?] cycloaddition reaction. The rates of the forward and reverse reactions of this photochromic process are cation dependent; in particular the rate of the thermal reverse reaction is decreased by smaller cations and increased by larger cations, especially Rb+. The metal binding constants in methanol for 2 and 5 have been determined, revealing that the cryptand 5 binds Na+ and Rb+ more weakly than crown ether 2 by over two orders of magnitude.

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More information

Published date: 2002
Keywords: crown compounds, host-guest systems, molecular devices, photochromism, photoswitches

Identifiers

Local EPrints ID: 39115
URI: http://eprints.soton.ac.uk/id/eprint/39115
ISSN: 0947-6539
PURE UUID: e0336667-7253-4601-8d7c-55101e76b185
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272
ORCID for Mark E. Light: ORCID iD orcid.org/0000-0002-0585-0843

Catalogue record

Date deposited: 21 Jun 2006
Last modified: 09 Jan 2022 02:59

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Contributors

Author: Gordon McSkimming
Author: James H. R. Tucker
Author: Henri Bouas-Laurent
Author: Jean-Pierre Desvergne
Author: Simon J. Coles ORCID iD
Author: Mark E. Light ORCID iD

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