Ballardini, RobertoBalzani, VincenzoCredi, A. (Alberto), 1970-Gandolfi, Maria TeresaProdi, LucaVenturi, MargheritaPérez García, M. Lluïsa (Maria Lluïsa)Stoddart, J. Frasser2020-07-222020-07-2219950016-5603https://hdl.handle.net/2445/169288The 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.7 p.application/pdfeng(c) Ballardini, Roberto et al., 1995FotoquímicaNanoquímicaCompostos heterocíclicsPhotochemistryNanochemistryHeterocyclic compoundsinfo:eu-repo/semantics/article1119762020-07-22info:eu-repo/semantics/openAccess