title: NIR emission of cyclic [4]rotaxanes containing π-extended porphyrin chromophores.
abstract: The photophysical properties of a Cu(I) [4]rotaxane 4(4+) and of the demetalated [4]rotaxane 3 have been determined and compared to those of the component Zn porphyrin 2. All samples emit in the NIR region (700-1200 nm). The luminescence from the interlocked structures is bathochromically shifted with respect to 2 and displays a lower emission quantum yield, much lower for 4(4+) than for 3. The occurrence of intra-molecular electron or energy transfer is excluded and the decrease in luminescence yield is discussed in terms of the energy gap law and of electronic interactions between components of the cyclic interlocked structure. In toluene a dual emission behavior, similar to that of 2, is observed for 3 and ascribed to the presence of two non-equilibrated excited states, π-π* and CT in nature with lifetimes of 0.80 and 0.14 ns, respectively.
authors: Istituto ISOF-CNR, Via P. Gobetti 101, 40129 Bologna, Italy.
authors: Barbara
authors: B
authors: Ventura
authors: Lucia
authors: L
authors: Flamigni
authors: Jean-Paul
authors: JP
authors: Collin
authors: Fabien
authors: F
authors: Durola
authors: Valérie
authors: V
authors: Heitz
authors: Felipe
authors: F
authors: Reviriego
authors: Jean-Pierre
authors: JP
authors: Sauvage
authors: Yann
authors: Y
authors: Trolez