Electron Transfer in Nonpolar Solvents in Fullerodendrimers with Peripheral Ferrocene Units

Abstract

Two new fullerodendrimers, with two and four ferrocene units on their periphery, have been synthesized by 1,3-dipolar cycloaddition reactions between the corresponding azomethine ylides and C(60). These new compounds have been studied by using cyclic voltammetry and UV/Vis spectroscopy. Weak intramolecular interactions between the fullerene cage and the ferrocene groups have been found. The photochemical events of both fullerene-ferrocene dendrimers have been probed by means of steady-state and time-resolved techniques. The steady-state emission intensities of the fulleropyrrolidine-ferrocene dendrimers 1 and 2 were found to be quenched relative to the N-methylfulleropyrrolidine without substituents that was used as a model. The nanosecond transient absorption spectral studies revealed efficient charge separation in both systems, even in toluene. The lifetimes of the (C(60))(*-)-(dendron)(*+) are higher for the second-generation fullerodendrimer (with four ferrocene units) and they are of the order of tens of nanoseconds in toluene and hundreds of nanoseconds in polar solvents.

Comparison between the Photophysical Properties of Pyrazolo‐ and Isoxazolo[60]fullerenes with Dual Donors (Ferrocene, Aniline and Alkoxyphenyl)

“…First, the dual-donor systems are better than the monodonor systems in obtaining prolonged charge-separation states with the trends as reported for the multidonor systems. [9,10] The second point revealed in the present study is the effect of the bridges (pyrazoline and isoxazoline rings) used to connect the donors to the fullerene moieties; the pyrazoline ring acts as a better bridge than isoxazoline in the sense of high charge-separation efficiencies and slow charge-recombination rates.…”

“…Hydrazones 4a-c were prepared in good yields (65-90 %) by the reaction of aldehydes 3a-c [10,18] with 4-nitrophenylhydrazine in refluxing EtOH. [19] Two different procedures were used for the preparation of pyrazolo-fullerenes 1a-c. Derivatives 1a and 1b were obtained (in 19 and 15 % yields, respectively) by the reaction of 4a and 4b with N-chlorosuccinimide (NCS) in CHCl 3 at 0°C and subsequent addition Scheme 2. of C 60 and Et 3 N in toluene at room temperature to afford cycloadducts 1a and 1b.…”

“…[7] The donor ability of peripheral groups determines the nature of photophysical events in these systems; alkoxy groups only drive energy transfer, [8] but stronger donors in the periphery (e.g., multi-dibutylaniline [9] and multi-ferrocene units [10] ) allow efficient electron transfer that generates the radical-ion pair.…”

Phase behavior and electron transfer properties of ferrocenyl cholesteryl N-formanidoformamide gelator: a computational study

“…For instance, Xu et al studied the influence of solvent viscosity on the aggregation of LMOGs [16]; Perez et al investigated the solvent effect on the electron transfer of ferrocene derivatives [17]. Although a tremendous amount of experimental work has been devoted to the investigation of conductive-gel systems, theoretical support is still needed to address critical problems such as the interaction of solvent and gelators during aggregation, the phase transition of gels, and the electron transport properties in gel systems.…”

Photoinduced Electron Transfer in Branched Bis(ferrocenylacetylene)‐C60Systems: Influence of the Nature of Conjugation

“…[9] The nanosecond transient absorption spectral studies revealed efficient photoinduced charge separation even in toluene as solvent, which is prospective for wide applications in non-polar media such as polymer films. Interestingly, when the same donor moiety Scheme 1.…”