A Supramolecular Photosynthetic Model Made of a Multiporphyrinic Array Constructed around a C₆₀ Core and a C₆₀–Imidazole Derivative

Abstract

The photophysical properties of a supramolecular fullerene-porphyrin ensemble resulting from the self-assembly of a pyrrolidinofullerene-imidazole derivative (F1) with a multimetalloporphyrin array constructed around a hexasubstituted fullerene core (F(ZnP)12) have been investigated. The fullerene hexa-adduct core of the host system does not play any active role in the cascade of photoinduced events of the supramolecular ensemble, indeed no intercomponent photoinduced processes could be observed in host F(ZnP)12. In contrast, upon axial coordination with the monosubstituted fullerene guest F1, a quantitative quenching of the fluorescence signal of the metalloporphyrins was observed for the supramolecular complex [F(ZnP)12(F1)n] both in polar and nonpolar solvents. In toluene, the supramolecular ensemble exhibits a charge transfer emission centered around nm, suggesting the occurrence of intramolecular face-to-face interactions of F1 with neighboring metalloporphyrin moieties within the self-assembled photoactive array. This mechanism is supported by the fact that a one order of magnitude increase in the binding constant was observed for the supramolecular complex [F(ZnP)12(F1)n] when compared with a reference system lacking the pyrrolidinofullerene unit. In benzonitrile, a long-lived charge-separated state (τ=0.3 μs) has been detected for the supramolecular adduct.

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

“…Apart from their unique architecture, hexakis adducts derived from the functionalization of the six e double bonds of C 60 are very attractive structures in the synthesis of functional fullerene materials. [45][46][47][48][49][50] The results of the present study lead to the conclusion that the [4+2] cycloaddition of orthoquinodimethanes with the C 60 is a kinetically controlled reaction. The in situ thermal generation of ortho-quinodimethanes from the corresponding 1,2-bis(bromomethyl)benzene precursors requires high temperatures (110 o C) and is followed by the fast, irreversible [4+2] cycloaddition reaction with C 60 to afford thermally stable products.…”

Coordination chemistry on carbon surfaces

“…43) was synthesized in order to study its photophysical properties. In one case the hexafullerene core does not participate in the photoinduced events, actually, it perturbates the system making it a less efficient energy and electron acceptor, in contrast a quantitative quenching of the fluorescence signal of the metalloporphyrins was observed changing some substituents on the pyrrilidino-fullerene [316]. 6 -coordination mode that largely preserves the graphitic band structure.…”

The Impact of Copper‐Catalyzed Alkyne–Azide 1,3‐Dipolar Cycloaddition in Fullerene Chemistry

“…To this end, we have investigated the supramolecular ensemble resulting from the self-assembly of pyrrolidinofullerene-imidazole [39] derivative 40 with multi-metalloporphyrin array 39 ( Figure 3). [38] Upon axial coordination of mono-substituted fullerene guest 40 to the multi-topic receptor 39, a quantitative quenching of the fluorescence signal of the metalloporphyrins was observed for the resulting supramolecular complex [(39) (40)n]. In a nonpolar solvent (toluene), this species exhibits a NIR emission at around 930 nm that has been attributed to a charge-transfer emissive state that arises from intramolecular face-to-face interactions of the axially coordinated 40 moiety with a neighboring porphyrin.…”

“…In contrast to what was observed for fullerene-porphyrin conjugate 38, no intercomponent photoinduced processes could be observed in 39 regardless of the solvent. [38] The hexafunctionalization of the central core of 39 results in extensive breaking of the π-fullerene structure, as evidenced by the blueshifted emission spectra and the dramatic potential shift for the first reduction wave when compared to fullerene mono-and bis-adducts (ca. 1 V).…”

“…Among them, a few examples have been prepared from clickable fullerene building blocks. [17,[36][37][38] Typical examples are shown in Figures 1 and 2.…”