Elke Dietel

Globular dendrimers involving a C60 core and a tetraphenyl porphyrin function

The nanoenvironment provided by the neighboring dendra characteristically influences the redox potentials and the photophysical properties of the tetraphenylporphyrin–zinc (Zn-TPP; denoted as P in Figure) chromophore within the dendrimers 1, which are based on C60 as a structure-determining core. Such functional dendrimers represent a new prototype of model systems for heme proteins (1).

Photoinduced electron transfer in multicomponent arraysof a π-stacked fullerene porphyrin dyad and diazabicyclooctane or afulleropyrrolidine ligand

The kinetics of photoinduced electron transfer in new multicomponent arrays of a π-stacked fullerene porphyrin dyad and diazabicyclooctane or a fulleropyrrolidine ligand have been determined and depend on the molecular architecture

A macrocyclic [60]fullerene–porphyrin dyad involving π–π stacking interactions

The very regioselective twofold cyclopropanation of C60 with a porphyrin bismalonate leads to a C2 symmetrical [60]fullerene–porphyrin dyad with pronounced electronic interactions between the two π–π stacked chromophores.

Charge-transfer in a π-stacked fullerene porphyrin dyad: evidence for back electron transfer in the ‘Marcus-inverted’ region

The ‘Marcus-inverted’ region for BET in a π–π stacked fullerene–porphyrin dyad was determined based on (i) the photoactivation of an intramolecular ET in a variety of solvents and (ii) the formation of a highly energetic charge-separated state

Synthesis and electrochemical investigations of molecular architectures involving C60 and tetraphenylporphyrin as building blocks

A C60–porphyrin diad 3a has been prepared by connecting a zinc porphyrin and C60via nucleophilic cyclopropanation. The fullerene diad as well as the related precursor porphyrins 1a, 2a have been investigated by cyclic and differential pulse voltammetry in dichloromethane. Whereas no oxidation peaks were observed for C60, all compounds 1a–3a exhibit two successive, quasi-reversible oxidation peaks in terms of an EE mechanism. The peak potentials of all three species almost coincide, due to an oxidation of the porphyrin ring system in all cases. In the cathodic process, on the other hand, the compounds are reduced in quasi-reversible four (C60), two (1a,2a) and five (3a) one-electron transfers. The first two formal potentials of 3a (resulting from the C60 moiety) are shifted towards negative potentials by 40 mV, as compared to C60, which is typical for methanofullerenes. Aside from coulombic effects, there is almost no electronic interaction between the C60 and porphyrin parts in 3a. Furthermore, a mixed hexaadduct 4 of C60 with an octahedral addition pattern incorporating a zinc tetraphenylporphyrin has been synthesized.

EPR studies of N@C60 and its adducts

Atomic Nitrogen in its quartet ground state can be encapsulated in C60 and its derivatives of reduced symmetry. Three endohedral fullerenes were studied in solid matrices for a determination of the permanent zero-field-splitting tensors. In solution the lowering of the site symmetry by collision-induced deformations of the fullerene cage apparently leads to a time dependent zero-field-splitting of the quartet spin state. The variance of the zero-field-splitting and the correlation time of this interaction are estimated from the absolute values of T1 and T2.