Rigidified tetrathiafulvalene–[60]fullerene assemblies: towards the control of through-space orientation between both electroactive units

Abstract

Our recent works on fused TTF-C 60 dyads, (TTF) n -C 60 polyads and C 60 -TTF-C 60 dumbbell triads in which the acceptor C 60 is doubly tethered to the donor tetrathiafulvalene through a rigidified cyclohexene ring are presented. This approach was developed in order to control the relative orientation as well as the distance between both donor and acceptor entities. Thereby, through-space interactions which are of great importance for photoinduced electron-and/or energy-transfer processes are expected to dominate because of the special topology of the molecules. The two linked C 60 and TTF chromophores in such adducts are not only in close proximity but also have optimal orbital orientations, thus facilitating these through-space electronic interactions. These new C 60 -based assemblies were synthesized by [4 1 2] Diels-Alder cycloaddition reactions. The different methodologies considered for their synthesis are discussed, their analytical, spectroscopic characterizations and electrochemical properties are also described. The selective electro-oxidation or reduction afforded the corresponding radical cation and radical anion which were characterized by EPR. These C 60 -based assemblies were studied for their nonlinear optical and optical limiting applications. Moreover, intramolecular photoinduced charge-separation and charge-recombination processes in a fused C 60 -TTF-C 60 dumbbell triad which was designed to be soluble in organic solvents were investigated by time-resolved absorption and fluorescence techniques. Appreciable interaction between the C 60 moiety and TTF moiety in the ground state was suggested by steady-state absorption spectra and the fluorescence spectra showed considerable interaction in the singlet excited state. The nanosecond transient absorption spectra displayed the formation of the chargeseparated radical pair C 60 -TTF ? 1 -C 60 ? 2 , characterized by a lifetime of ca. 20 ns in benzonitrile.

Study of the contact charge transfer behavior between cryptophanes (A and E) and fullerene by absorption, fluorescence and 1H NMR spectroscopy

“…Many studies on the application of CT have focused in developing light-energy conversion systems and molecular photonic devices [1][2][3]. CT is an important process in biological systems such as drug action, enzyme catalysis and ion transfer that involves CT complexes [4][5][6].…”

Fulereno[C60]: química e aplicações

“…Vários outros exemplos de aplicação de derivados fulerênicos em óptica não linear podem ser encontrados na literatura destacando-se a síntese de C 60 -tetratiafulvalenos, 106 de fulerodendrímeros 107 e de C 60 -oligo-p-fenilenoetinileno, 108 dentre outros.…”

Organofullerene Materials

“…Thus, fused tetrathiafulvalene-C 60 dyads and C 60 -tetrathiafulvalene-C 60 dumbbell triads, in which the fullerene acceptor is doubly tethered to the donor tetrathiafulvalene through a rigidified cyclohexene ring [108], were prepared.With this novel approach, control of the relative orientation as well as the distance between the donor and acceptor units was achieved. Thereby, through-space interactions were expected to dominate because of the special topology of the constructed molecules.…”