Rates and energetics of intramolecular electron transfer processes in conjugated metallofullerenes

Abstract

In this paper, we report on the design, redox potentials, excited state energies and radical ion pair state energies in electron donor–acceptor conjugates comprising the electron-donating π -extended tetrathia- fulvalene and several electron-accepting fullerenes. To this end, we contrast an empty fullerene, that is, C 60 , with two endohedral metallofullerenes, that is, open-shell La@C 82 and closed-shell La 2 @C 80 , in terms of charge separation and charge recombination dynamics.

A multicomponent molecular approach to artificial photosynthesis – the role of fullerenes and endohedral metallofullerenes

“…In this context, the impact that different metallofullerenes exert on the excited state energies, radical ion pair state energies, and, consequently, on the electron transfer dynamics relative to C 60 is of importance. 57 As evidenced by absorption spectroscopy and electrochemical measurements only weak electronic interactions were observed in the ground state despite the relatively close proximity between exTTF and fullerene/EMFs. C 60 , La@C 2v -C 82 , and La 2 @I h -C 80 are all versatile electron acceptors with first reduction potentials of À1.06, À0.38, and À0.45 V, respectively.…”

Efficient Energy-Conversion Materials for the Future: Understanding and Tailoring Charge-Transfer Processes in Carbon Nanostructures

“…In the context of reductive electron transfer, stable electron donor-acceptor conjugates involving an exTTF electron donor and two EMFs, that is, the open-shell La@C 82 and the closed-shell La 2 @C 80 , have been studied in comparison with a C 60 -analog conjugate (Scheme 1, structure 8). 40,41 Despite the relatively close proximity between exTTF and fullerene/EMFs, absorption and electrochemical measurements reveal only weak electronic interactions in the ground state. Notably, far lower redox potentials (versus Fc/Fc + ) than with C 60 (À1.06 V) render La@C 82 (À0.38 V) and La 2 @C 80 (À0.45 V) better electron acceptors, which leads to different thermodynamics in the form of larger driving forces for charge separation.…”

Metallofullerene photoswitches driven by photoinduced fullerene-to-metal electron transfer

“…[21][22][23][24][25][26] But currently, surprisingly little is known about the photophysics of EMFs. Their role as electron donors or acceptors in molecular dyads undergoing photoinduced charge transfer had been studied comprehensively, [27][28][29][30][31][32][33][34][35][36][37][38] but the properties of pristine EMFs, including those of iconic Sc 3 N@C 80 , are not well known. 35,37,[39][40][41] For empty fullerenes, very efficient S 1 / T 1 intersystem crossing leads to almost 100% yield of a triplet state aer photoexcitation.…”