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Title: Photochemical, Photophysical and Electrochemical Properties of a Photoisomerizable Cyclophane and its [2]Catenates with Aromatic Crown Ethers
Author: Ballardini, Roberto
Balzani, Vincenzo
Credi, A. (Alberto), 1970-
Gandolfi, Maria Teresa
Prodi, Luca
Venturi, Margherita
Pérez García, M. Lluïsa (Maria Lluïsa)
Stoddart, J. Frasser
Keywords: Fotoquímica
Compostos heterocíclics
Heterocyclic compounds
Issue Date: 1995
Publisher: Società Chimica Italiana
Abstract: 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.
Note: Reproducció del document publicat a:
It is part of: Gazzetta Chimica Italiana, 1995, vol. 125, p. 353-359
ISSN: 0016-5603
Appears in Collections:Articles publicats en revistes (Farmacologia, Toxicologia i Química Terapèutica)

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