A non-covalent strategy to prepare electron donor–acceptor rotaxanes

Abstract

A straightforward non-covalent synthetic strategy for producing donor-acceptor rotaxanes is reported. Femtosecond absorption spectroscopy illustrates that the use of this strategy gives rise to supramolecular chromophores with different electron transfer behavior.

Carbon Nanostructures in Rotaxane Architectures

“…Rotaxanes containing C 60 as the electron‐acceptor component and different types of electron‐donors have been reported in the literature. Among them, porphyrins and phthalocyanines have been widely explored as the electron‐donors, in which charge separation (CS) process can occur through the singlet or triplet excited states, depending on the distance between the components , . Furthermore, changes in the relative distance between donors and acceptors seems to play a key role in the photoinduced electron transfer (PET) process .…”

Extremely fast triplet formation by charge recombination in a Nile Red/fullerene flexible dyad

“…2 RP-ISC was observed for many electron donor/acceptor polyads with large separation distance between the electron donor and acceptor units. 10,12,[17][18][19][20][21] Typically, relatively slow rates of triplet CR (o10 8 s À1 ) have been reported for the RP-ISC pathway, while substantially faster rates (410 9 , up to 2.5 Â 10 10 s À1 ) have been correlated to the SOCT-ISC mechanism. 1 However, distinguishing between the two mechanisms is not easy and would require time-resolved electron paramagnetic resonance (TREPR).…”

“…While the dyad was designed to perform charge transfer, we observed an even more interesting behavior upon selective photoexcitation of Nile Red, leading to the very fast formation of a triplet state localized on C 60 . Other covalent or supramolecular fully organic donor/acceptor dyads comprising fullerene were reported in the literature, 20,21,23,[36][37][38][39][40][41] and some of them were able to form the fullerene triplet after photoexcitation of the donor. 20,21,23,40,41 To the best of our knowledge, however, our system is peculiar in terms of the impressive speed of formation of the triplet (B10 10 s À1 ), as well as of the little importance of the solvent polarity on the dynamics of the process.…”

Distance‐Dependent Electron Transfer Kinetics in Axially Connected Silicon Phthalocyanine‐Fullerene Conjugates

“…[1][2][3] Multichromophoric systems consisting of donor-acceptor assemblies are of great significance in designing new molecular architectures for artificial photosynthesis. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] To investigate their potential use in artificial photosynthesis, these molecular building blocks should demonstrate novel photophysical characteristics including high tunability in the UV-Vis spectrum and the ability to harvest sunlight. Porphyrinoid electron-donor, usually porphyrins and phthalocyanines, are preferred for building artificial photosynthetic systems, due to their high molar extinction coefficients and photo-tunability.…”

“…Multichromophoric systems consisting of donor‐acceptor assemblies are of great significance in designing new molecular architectures for artificial photosynthesis . To investigate their potential use in artificial photosynthesis, these molecular building blocks should demonstrate novel photophysical characteristics including high tunability in the UV‐Vis spectrum and the ability to harvest sunlight.…”