Abstract
Two acyclic and three macrocyclic polyethers, three [2]catenanes, and one [2]rotaxane, each containing one 4,4′-azobiphenoxy unit, have been synthesized. In solution, the azobenzene-based acyclic polyethers are bound by cyclobis(paraquat-p-phenylene) - a tetracationic cyclophane - in their trans forms only. On irradiation (λ = 360 nm) of an equimolar solution of the tetracationic cyclophane host and one of the guests containing a trans-4,4′-azobiphenoxy unit, the trans double bond isomerizes to its cis form and the supramolecular complex dissociates into its molecular components. The trans isomer of the guest and, as a result, the complex are reformed, either by irradiation (λ = 440 nm) or by warming the solution in the dark. Variable temperature 1H NMR spectroscopic investigations of the [2]catenanes and the [2]rotaxane revealed that, in all cases, the 4,4′-azobiphenoxy unit resides preferentially alongside the cavities of their tetracationic cyclophane components, which are occupied either by a 1,4-dioxybenzene or by a 1,5-dioxynaphthalene unit. In the acyclic and macrocyclic polyethers containing 1,4-dioxybenzene or 1,5-dioxynaphthalene chromophoric groups and a 4,4′-azobiphenoxy moiety, the fluorescence of the former units is quenched by the latter. Fluorescence quenching is accompanied by photosensitization of the isomerization. The rate of the energy-transfer process is different for trans and cis isomers. In the [2]rotaxane and the [2]catenanes, the photoisomerization is quenched to an extent that depends on the specific structure of the compound. Only in one of the three [2]catenanes and in the [2]rotaxane was an efficient photoisomerization (λ = 360 nm) from the trans to the cis isomer of the 4,4′-azobiphenoxy unit observed. Single crystal X-ray structural analysis of one of the [2]catenanes showed that, in the solid state, the 4,4′-azobiphenoxy unit in the macrocyclic polyether component also resides exclusively alongside. The cavity of the tetracationic cyclophane component of the [2]catenane is filled by a 1,5-dioxynaphthalene unit, and infinite donor-acceptor stacks between adjacent [2]catenanes are formed in the crystal. These supramolecular complexes and their mechanically interlocked molecular counterparts can be regarded as potential photoactive nanoscale devices.
| Original language | English |
|---|---|
| Pages (from-to) | 860-875 |
| Number of pages | 16 |
| Journal | Chemistry - A European Journal |
| Volume | 5 |
| Issue number | 3 |
| State | Published - Dec 1 1999 |
| Externally published | Yes |
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Keywords
- Catenanes
- Molecular devices
- Molecular recognition
- Rotaxanes
- Template synthesis
ASJC Scopus subject areas
- Chemistry(all)
Cite this
Photoactive azobenzene-containing supramolecular complexes and related interlocked molecular compounds. / Asakawa, Masumi; Ashton, Peter R.; Balzani, Vincenzo; Brown, Christopher L.; Credi, Alberto; Matthews, Owen A.; Newton, Simon P.; Raymo, Francisco; Shipway, Andrew N.; Spencer, Neil; Quick, Andrew; Stoddart, J. Fraser; White, Andrew J P; Williams, David J.
In: Chemistry - A European Journal, Vol. 5, No. 3, 01.12.1999, p. 860-875.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photoactive azobenzene-containing supramolecular complexes and related interlocked molecular compounds
AU - Asakawa, Masumi
AU - Ashton, Peter R.
AU - Balzani, Vincenzo
AU - Brown, Christopher L.
AU - Credi, Alberto
AU - Matthews, Owen A.
AU - Newton, Simon P.
AU - Raymo, Francisco
AU - Shipway, Andrew N.
AU - Spencer, Neil
AU - Quick, Andrew
AU - Stoddart, J. Fraser
AU - White, Andrew J P
AU - Williams, David J.
PY - 1999/12/1
Y1 - 1999/12/1
N2 - Two acyclic and three macrocyclic polyethers, three [2]catenanes, and one [2]rotaxane, each containing one 4,4′-azobiphenoxy unit, have been synthesized. In solution, the azobenzene-based acyclic polyethers are bound by cyclobis(paraquat-p-phenylene) - a tetracationic cyclophane - in their trans forms only. On irradiation (λ = 360 nm) of an equimolar solution of the tetracationic cyclophane host and one of the guests containing a trans-4,4′-azobiphenoxy unit, the trans double bond isomerizes to its cis form and the supramolecular complex dissociates into its molecular components. The trans isomer of the guest and, as a result, the complex are reformed, either by irradiation (λ = 440 nm) or by warming the solution in the dark. Variable temperature 1H NMR spectroscopic investigations of the [2]catenanes and the [2]rotaxane revealed that, in all cases, the 4,4′-azobiphenoxy unit resides preferentially alongside the cavities of their tetracationic cyclophane components, which are occupied either by a 1,4-dioxybenzene or by a 1,5-dioxynaphthalene unit. In the acyclic and macrocyclic polyethers containing 1,4-dioxybenzene or 1,5-dioxynaphthalene chromophoric groups and a 4,4′-azobiphenoxy moiety, the fluorescence of the former units is quenched by the latter. Fluorescence quenching is accompanied by photosensitization of the isomerization. The rate of the energy-transfer process is different for trans and cis isomers. In the [2]rotaxane and the [2]catenanes, the photoisomerization is quenched to an extent that depends on the specific structure of the compound. Only in one of the three [2]catenanes and in the [2]rotaxane was an efficient photoisomerization (λ = 360 nm) from the trans to the cis isomer of the 4,4′-azobiphenoxy unit observed. Single crystal X-ray structural analysis of one of the [2]catenanes showed that, in the solid state, the 4,4′-azobiphenoxy unit in the macrocyclic polyether component also resides exclusively alongside. The cavity of the tetracationic cyclophane component of the [2]catenane is filled by a 1,5-dioxynaphthalene unit, and infinite donor-acceptor stacks between adjacent [2]catenanes are formed in the crystal. These supramolecular complexes and their mechanically interlocked molecular counterparts can be regarded as potential photoactive nanoscale devices.
AB - Two acyclic and three macrocyclic polyethers, three [2]catenanes, and one [2]rotaxane, each containing one 4,4′-azobiphenoxy unit, have been synthesized. In solution, the azobenzene-based acyclic polyethers are bound by cyclobis(paraquat-p-phenylene) - a tetracationic cyclophane - in their trans forms only. On irradiation (λ = 360 nm) of an equimolar solution of the tetracationic cyclophane host and one of the guests containing a trans-4,4′-azobiphenoxy unit, the trans double bond isomerizes to its cis form and the supramolecular complex dissociates into its molecular components. The trans isomer of the guest and, as a result, the complex are reformed, either by irradiation (λ = 440 nm) or by warming the solution in the dark. Variable temperature 1H NMR spectroscopic investigations of the [2]catenanes and the [2]rotaxane revealed that, in all cases, the 4,4′-azobiphenoxy unit resides preferentially alongside the cavities of their tetracationic cyclophane components, which are occupied either by a 1,4-dioxybenzene or by a 1,5-dioxynaphthalene unit. In the acyclic and macrocyclic polyethers containing 1,4-dioxybenzene or 1,5-dioxynaphthalene chromophoric groups and a 4,4′-azobiphenoxy moiety, the fluorescence of the former units is quenched by the latter. Fluorescence quenching is accompanied by photosensitization of the isomerization. The rate of the energy-transfer process is different for trans and cis isomers. In the [2]rotaxane and the [2]catenanes, the photoisomerization is quenched to an extent that depends on the specific structure of the compound. Only in one of the three [2]catenanes and in the [2]rotaxane was an efficient photoisomerization (λ = 360 nm) from the trans to the cis isomer of the 4,4′-azobiphenoxy unit observed. Single crystal X-ray structural analysis of one of the [2]catenanes showed that, in the solid state, the 4,4′-azobiphenoxy unit in the macrocyclic polyether component also resides exclusively alongside. The cavity of the tetracationic cyclophane component of the [2]catenane is filled by a 1,5-dioxynaphthalene unit, and infinite donor-acceptor stacks between adjacent [2]catenanes are formed in the crystal. These supramolecular complexes and their mechanically interlocked molecular counterparts can be regarded as potential photoactive nanoscale devices.
KW - Catenanes
KW - Molecular devices
KW - Molecular recognition
KW - Rotaxanes
KW - Template synthesis
UR - http://www.scopus.com/inward/record.url?scp=0033064484&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033064484&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0033064484
VL - 5
SP - 860
EP - 875
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 3
ER -