Abstract
Photoresponsive crown ethers (3) having an intra-annular azo substituent have been synthesized. These crown ethers have been designed so that the crown-metal interaction can only occur upon photoisomerisation of the intra-annular azo substituent from trans to cis. In thermal cis-to-trans isomerisation, the first-order rate constants (k) were suppressed to 14 - 66% by the addition of Na+ or K+, indicating that an additional free energy of activation (1.0 - 5.0 KJ mol-1) is required to disrupt the favourable crown-metal interactions. From the plots of k vs. [M +] the association constants (Kc) for the cis-forms were estimated to be 104.07 - 104.81 l mol-1, which are comparable with the Kc for regular crown ethers. The spectral study established that the high metal affinity of the cis-forms is due to the co-ordination of one of the azo nitrogens to the metal ion. In two-phase extraction of alkali-metal cations the Ex% values for cis-(3) were always higher than those for trans-(3). In particular, the dramatic photoirradiation effect was observed for Na+: cis-(3) extracts Na+ (8.1-14.1%), whereas trans-(3) extracts no Na+. This system was applied to ion transport across a liquid membrane. As expected, Na+ transport occurred only when the membrane phase was irradiated by u.v. light. The marked difference can be used to control the ion permeability by an on-off light switch.
| Original language | English |
|---|---|
| Pages (from-to) | 449-456 |
| Number of pages | 8 |
| Journal | Journal of the Chemical Society, Perkin Transactions 1 |
| Publication status | Published - 1987 |
| Externally published | Yes |
Fingerprint
All Science Journal Classification (ASJC) codes
- Chemistry(all)
Cite this
Photoresponsive crown ethers. Part 18. Photochemically 'switched-on' crown ethers containing an intra-annular azo substituent and their application to membrane transport. / Shinkai, Seiji; Miyazaki, Kiminori; Manabe, Osamu.
In: Journal of the Chemical Society, Perkin Transactions 1, 1987, p. 449-456.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photoresponsive crown ethers. Part 18. Photochemically 'switched-on' crown ethers containing an intra-annular azo substituent and their application to membrane transport
AU - Shinkai, Seiji
AU - Miyazaki, Kiminori
AU - Manabe, Osamu
PY - 1987
Y1 - 1987
N2 - Photoresponsive crown ethers (3) having an intra-annular azo substituent have been synthesized. These crown ethers have been designed so that the crown-metal interaction can only occur upon photoisomerisation of the intra-annular azo substituent from trans to cis. In thermal cis-to-trans isomerisation, the first-order rate constants (k) were suppressed to 14 - 66% by the addition of Na+ or K+, indicating that an additional free energy of activation (1.0 - 5.0 KJ mol-1) is required to disrupt the favourable crown-metal interactions. From the plots of k vs. [M +] the association constants (Kc) for the cis-forms were estimated to be 104.07 - 104.81 l mol-1, which are comparable with the Kc for regular crown ethers. The spectral study established that the high metal affinity of the cis-forms is due to the co-ordination of one of the azo nitrogens to the metal ion. In two-phase extraction of alkali-metal cations the Ex% values for cis-(3) were always higher than those for trans-(3). In particular, the dramatic photoirradiation effect was observed for Na+: cis-(3) extracts Na+ (8.1-14.1%), whereas trans-(3) extracts no Na+. This system was applied to ion transport across a liquid membrane. As expected, Na+ transport occurred only when the membrane phase was irradiated by u.v. light. The marked difference can be used to control the ion permeability by an on-off light switch.
AB - Photoresponsive crown ethers (3) having an intra-annular azo substituent have been synthesized. These crown ethers have been designed so that the crown-metal interaction can only occur upon photoisomerisation of the intra-annular azo substituent from trans to cis. In thermal cis-to-trans isomerisation, the first-order rate constants (k) were suppressed to 14 - 66% by the addition of Na+ or K+, indicating that an additional free energy of activation (1.0 - 5.0 KJ mol-1) is required to disrupt the favourable crown-metal interactions. From the plots of k vs. [M +] the association constants (Kc) for the cis-forms were estimated to be 104.07 - 104.81 l mol-1, which are comparable with the Kc for regular crown ethers. The spectral study established that the high metal affinity of the cis-forms is due to the co-ordination of one of the azo nitrogens to the metal ion. In two-phase extraction of alkali-metal cations the Ex% values for cis-(3) were always higher than those for trans-(3). In particular, the dramatic photoirradiation effect was observed for Na+: cis-(3) extracts Na+ (8.1-14.1%), whereas trans-(3) extracts no Na+. This system was applied to ion transport across a liquid membrane. As expected, Na+ transport occurred only when the membrane phase was irradiated by u.v. light. The marked difference can be used to control the ion permeability by an on-off light switch.
UR - http://www.scopus.com/inward/record.url?scp=37049082045&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=37049082045&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:37049082045
SP - 449
EP - 456
JO - Journal of the Chemical Society, Perkin Transactions 2
JF - Journal of the Chemical Society, Perkin Transactions 2
SN - 1472-7781
ER -