Photochemical, Photophysical and Electrochemical Properties of a Photoisomerizable Cyclophane and its [2]Catenates with Aromatic Crown Ethers
The photochemical, photophysical, and electrochemical behaviour of t-1,2-bis(1-benzy1-4- pyridinium)ethylene (t-DBBPE2+) (used as model compound), a cyclophane made of two t-1,2-bis(4-pyridin-ium)ethylene (BPE) units (141, and its catenanes (1B134+,1BN4+, and INN') with aromatic crown ethers co...
| Autores: | , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 1995 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/169288 |
| Acceso en línea: | https://hdl.handle.net/2445/169288 |
| Access Level: | acceso abierto |
| Palabra clave: | Fotoquímica Nanoquímica Compostos heterocíclics Photochemistry Nanochemistry Heterocyclic compounds |
| Sumario: | The photochemical, photophysical, and electrochemical behaviour of t-1,2-bis(1-benzy1-4- pyridinium)ethylene (t-DBBPE2+) (used as model compound), a cyclophane made of two t-1,2-bis(4-pyridin-ium)ethylene (BPE) units (141, and its catenanes (1B134+,1BN4+, and INN') with aromatic crown ethers containing two p-dimethoxybenzene units (BB), one p-dimethoxybenzene and one 1,5-dimethoxynaphthalene unit (BN), and two 1,5-dimethoxynaphthalene units (NN) have been investigated in acetonitrile solution. For both t-DBBPE' and 14+, fluorescence and direct trans-*cis photoisomerization are prevented by the presence of an intramolecular charge-transfer (CT) excited state close to or below the lire level, but the triplet-sensitized photoisomerization takes place with high quantum yield. In the 1BB4*, 1BN4', and 1NN4' catenanes, also the triplet sensitized photoisomerization is quenched by the presence of lower lying inter-component CT levels. The intercomponent CT interaction present in the catenanes affects the reduction potentials of the t-DBBPE2+ units of 14+. Such an interaction, which plays the role of a brake against the free rotation of the two rings of catenanes, is released upon reduction of the 14+ cyclophane. |
|---|