Azafullerene C₅₉N–Phthalocyanine Dyad: Synthesis, Characterisation and Photoinduced Electron Transfer

Abstract

The synthesis of a new azafullerene C(59)N-phthalocyanine (Pc) dyad is described. The key step for the synthesis of the C(59)N-Pc dyad was the formation of the C(59)N-based carboxylic acid, which was smoothly condensed with hydroxy-modified Pc. The structure of the C(59)N-Pc dyad was verified by (1)H and (13)C NMR spectroscopy, IR spectroscopy, UV/Vis spectroscopy and MS measurements. The photophysical and electrochemical properties of the C(59)N-Pc dyad were investigated in both polar and non-polar solvents by steady state and time-resolved photoluminescence and absorption spectroscopy, as well as by cyclic voltammetry. Different relaxation pathways for the photoexcited C(59)N-Pc dyad, as a result of changing the solvent polarity, were found, thus giving rise to energy-transfer phenomena in non-polar toluene and charge-transfer processes in polar benzonitrile. Finally, the detailed quenching mechanisms were evaluated and compared with that of a C(60)-Pc dyad, which revealed that the different excited-state energies and reduction potentials of the two fullerene spheres (i.e. C(59)N vs. C(60)) strongly diverged in the deactivation pathways of the excited states of the corresponding phthalocyanine dyads.

Tether‐Directed Regioselective Synthesis of an Equatorialface Bisadduct of Azafullerene Using Cyclo‐[2]‐octylmalonate

“…In the case of C 59 N, addition of the first malonate moiety decreases the LUMO energy by 0.06 eV, specifically from −3.89 eV for (C 59 N) 2 to −3.95 eV for monoadduct 2 . This is analogous to observations in previous studies, with opposing trends being reported for C 60 monoadducts. Addition of the second malonate to C 59 N forming bisadduct (±)‐ 3 raises the LUMO level to −3.81 eV, 0.08 eV higher than that of the parent (C 59 N) 2 .…”

“…In these, the addend is bound at the 2‐position adjacent to the nitrogen atom following electrophilic aromatic substitution with electron‐rich arenes or Mannich‐type nucleophilic substitution reactions (Figure a) . Several C 59 N‐based donor–acceptor hybrids have been synthesized, incorporating phthalocyanines, corrole, porphyrins, perylene, polycyclic aromatic hydrocarbons, ferrocene, or gold nanoparticles, and were shown to participate in ultrafast energy‐ or electron‐transfer processes. Notably, in a more recent example, an oligophenylenevinylene wire was conjugated to C 59 N, yielding an ultralong charge‐separation lifetime of 20 ms .…”

Zinc Phthalocyanine–Graphene Hybrid Material for Energy Conversion: Synthesis, Characterization, Photophysics, and Photoelectrochemical Cell Preparation

“…Re--cently, there have been substantial increases in power conversion efficiencies in DSSCs using unsymmetrically substituted ''push-pull'' zinc phthalocyanines with bulky substituents. 47--50 Among them, phthalocyanines have been also covalently and non--covalently connected with different electron acceptor carbon nanostructures, 51,52 such as C 60 , 53--56 C 59 N, 57 carbon nanotubes, 58 perylenebisi--mides 59--66 and the photoinduced electron and/or energy transfer properties of these systems have been studied for their use as artificial photosynthetic systems and in or--ganic solar cells.…”

Electronic Communication between two [10]cycloparaphenylenes and Bis(azafullerene) (C59N)2 Induced by Cooperative Complexation

“…The titration results establish the effective development of electronic interactions between the two species,w ithin the [10]CPP'(C 59 N) 2 &[10]CPP complex, in the excited state. Notably,t he absence of emission in the NIR range,t hat is, 800-950 nm, corresponding to the azafullerene emission, [26,27] implies weak, if any,s inglet-singlet energy transfer from [10]CPP to (C 59 N) 2 .W hile full TDDFT calculations are not possible on systems of this size,the PL response is consistent In conclusion, we rationalize that bis(azafullerene) (C 59 N) 2 can be complexed by two [10]CPP macrocycles, with the first one stabilizing the binding of the second by maximizing p-p,C ÀH-p,a sw ell as attractive London dispersion interactions,f orming [10]CPP'(C 59 N) 2 &[10]CPP. Theoretical simulations reveal an unexpected tilted structure with an asymmetric arrangement of the [10]CPPs on the (C 59 N) 2 .M oreover,electrochemical as well as photoluminescence studies deliver meaningful insight for the electronic communication.…”