Ultrafast photoinduced electron transfer to C60

Sension, Roseanne J.; Szarka, Arpad Z.; Smith, Garry R.; Hochstrasser, Robin M.

doi:10.1016/s0009-2614(91)85043-v

Cited by 220 publications

(122 citation statements)

References 13 publications

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“…Interestingly, these Ks values are one to two orders of magnitude larger than the actual formation constants reported [ 15,17 ] for ground-state chargetransfer complexes between anilines and fullerenes. Furthermore the sharp decrease of Ks in the series DMPT, DMA, TMB appears incompatible with a change in complexation constant if compared to other charge-transfer complexes containing related electron donors ~3.…”

Section: Resultsmentioning

confidence: 64%

“…As reported earlier, however, the quenching curves for more powerful electron donors such as N,N-dimethyl-p-toluidine (DMPT) and N,N-dimethylaniline (DMA) display an "upward" curvature indicative for a contribution of significant additional static quenching. Since it is known [ 12,15,17 ] that the fullerenes form ground-state complexes of the chargetransfer type with strong electron donors, one might assume that such complex formation is responsible for the static quenching. If 1 : l complex formation with an equilibrium constant Ks occurs, and this does not influence significantly the molar extinction at the excitation wavelength, the combined result of static and dynamic quenching on the ratio of the unquenched and quenched fluorescence (Io/I) is given by…”

Section: Resultsmentioning

confidence: 99%

“…Fascinating data are continuously reported now, regarding such topics as fulleride superconductivity [3 ], organo-metallic and organic fullerene derivatives [4][5][6][7] and photophysical properties of fullerenes [8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Williams

Verhoeven

1992

Chemical Physics Letters

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The fluorescence spectrum and fluorescence quantum yield of C7o were determined in a number of solvents at room temperature. A well resolved fluorescence excitation spectrum, which matches the absorption spectrum, was obtained over a broad wavelength region (250 to 580 nm, in n-hexane). The fluorescence lifetime (627 ps in benzene) was determined, thereby settling the uncertainty about the singlet lifetime of C7o. It is shown that the quenching of the fluorescence by organic electron donors involves both dynamic and static mechanisms. The contribution of the latter is much more pronounced than can be explained from the degree of ground-state charge transfer complexation. Analysis in terms ofa Perrin model indicates that long-range intermolecular electron transfer is important, with a radius of action that increases sharply when the donor oxidation potential is lowered.

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Section: Resultsmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 99%

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Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Williams

Verhoeven

1992

Chemical Physics Letters

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“…This value is consistent with data from the literature. 72 The combined 7 mL of C 60 toluene solution (including the diluted portions) was placed in a 16 mL wide mouth vial, and 0.3 mL of Triton X-100 was added. (Figure 1 depicts both the C 60 and Triton X-100 molecules.)…”

Section: Synthesis and Stock Concentrationmentioning

confidence: 99%

Photophysical Properties of C₆₀ Colloids Suspended in Water with Triton X-100 Surfactant: Excited-State Properties with Femtosecond Resolution

et al. 2009

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We examine the photophysics of a colloidal suspension of C 60 particles in a micellar solution of Triton X-100 and water, prepared via a new synthesis which allows high-concentration suspensions. The particle sizes are characterized by transmission electron microscopy and dynamic light scattering and found to be somewhat polydisperse in the range of 10-100 nm. The suspension is characterized optically by UV-vis spectroscopy, femtosecond transient absorption spectroscopy, laser flash photolysis, and z-scan. The ground-state absorbance spectrum shows a broad absorbance feature centered near 450 nm which is indicative of colloidal C 60 . The transient absorption dynamics, presented for the first time with femtosecond resolution, are very similar to that of thin films of C 60 and indicate a strong quenching of the singlet excited state on short time scales and evidence of little intersystem crossing to a triplet excited state. Laser flash photolysis reveals that a triplet excited-state absorption spectrum, which is essentially identical in shape to that of molecular C 60 solutions, does indeed arise, but with much lower magnitude and somewhat shorter lifetime. Z-scan analysis confirms that the optical response of this material is dominated by nonlinear scattering. IntroductionSince its discovery, 1 the uniquely symmetrical C 60 molecule has been widely studied, and many applications for it and its derivatives have been proposed, notably lubricants, 2 superconductors, 3 sensors, 4-7 solar cells, 8 and biomedical applications [9][10][11] such as drug delivery and photodynamic therapy. In particular, the photophysical properties of the C 60 molecule have been the subject of intense study. Many authors have reported on the photophysical properties of molecular solutions of C 60 . [12][13][14][15][16][17][18][19][20] Likewise, many authors have studied the photophysical and structural properties of solid films of C 60 . [21][22][23][24][25][26][27][28][29][30][31][32][33][34] Under certain conditions, C 60 forms stable colloidal assemblies in solvents. [35][36][37][38][39][40][41][42][43][44] Colloidal suspensions of C 60 particles can also be formed in binary solvent mixtures, in which one is a good solvent and the other is a poor solvent for C 60 . [45][46][47][48][49] Aqueous suspensions of colloidal C 60 particles are also formed by a number of methods, [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] including solubilization in micellar solutions. 55,61,[65][66][67][68][69] Some studies have been done of the photophysical properties of these colloidal fullerene suspensions. 67,68,70,71 The photochemical properties, and in particular the generation of reactive oxygen species (ROS) via intersystem crossing to the triplet state, have been of interest both for potential exploitation for photodynamic therapy 9 and regarding concerns about their potential environmental impact, because there have been reports of significant cytotoxicity effects. [50][51][52][53] This work reports on the excited-state dynamics o...

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“…The first studies of ground-state CT interactions of fullerenes with amines (N,N-dimethylaniline, DMA, and N,N-diethylaniline, DEA) were reported by Hochstrasser and co-workers 5 and by Wang. 6 More recently, additional studies with aromatic and aliphatic amines were published.…”

Section: Introductionmentioning

confidence: 99%

Stable Charge-Transfer Complexes versus Contact Complexes. Application to the Interaction of Fullerenes with Aromatic Hydrocarbons

Sarova¹,

Berberan‐Santos²

2004

J. Phys. Chem. B

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The methods of calculation of the equilibrium constants and electronic absorption spectra of charge-transfer complexes are discussed with special emphasis on the treatment of the contact interaction. In particular, a model for the pseudo-equilibrium of contact complexes is developed. It is shown that a small but nonzero effective equilibrium constant can be defined for contact pairs and all higher order contact complexes. The results are applied to the study of the interaction of C 60 and C 70 with naphthalene and 1-methylnaphthalene, with the main goal being to establish the nature of the interaction of the fullerenes with these aromatic hydrocarbons. It is concluded that only simple contact complexes are formed, for which several spectroscopic parameters are obtained. IntroductionCharge-transfer (CT) bands in electronic absorption spectra are often observed in solutions where the solvent-solute interaction is of the donor-acceptor type. They are also observed when a suitable donor-acceptor pair is dissolved in an inert solvent. However, the existence of a CT band does not imply the existence of a stable charge-transfer complex. Essentially unbound molecular pairs, the so-called contact pairs (which could also be called physical complexes), may also display a modified absorption spectrum, including the appearance of one or more broad, structureless CT bands. 1-3 The binding energy of contact pairs is negligible, that is, smaller than the thermal agitation energy (RT = 3 kJ mol -1 at 300 K), and the apparent formation equilibrium constant K is very small (typically between 0.1 and 1 M -1 , see Section 3) and temperature independent. However, for stable ground-state CT molecular complexes, the binding energy is significant and the formation equilibrium constant is much larger than the statistical pair value, decreasing with a temperature increase according to the van't Hoff equation.The existence of CT bands in the absorption spectrum of the contact pair implies that, unlike the ground state, some of its excited states have a significant binding energy. When the lowest excited state is bound, one can speak of an exciplex. However, it may also happen that the lowest excited state of the contact pair is of the locally excited (LE) type, the excitation being mainly localized in the donor or in the acceptor. In such a case, all CT bands correspond to transitions to higher excited states.There are, therefore, two types of contact pairs: (i) Those that form exciplexes (exciplex forming contact pairs), whose lowest CT band corresponds to a transition to the first excited state; and (ii) Those that do not form exciplexes, whose CT bands correspond to transitions to higher excited states (simple contact pairs). We note that the energy of (emissive) exciplexes is defined by the relevant band in the observed fluorescence spectrum whose frequency corresponds to the relaxed geometry of the excited complex and not to that of the Franck-Condon state relevant for absorption.

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Ultrafast photoinduced electron transfer to C60

Cited by 220 publications

References 13 publications

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Photophysical Properties of C₆₀ Colloids Suspended in Water with Triton X-100 Surfactant: Excited-State Properties with Femtosecond Resolution

Stable Charge-Transfer Complexes versus Contact Complexes. Application to the Interaction of Fullerenes with Aromatic Hydrocarbons

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Ultrafast photoinduced electron transfer to C60

Cited by 220 publications

References 13 publications

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Photophysical Properties of C60 Colloids Suspended in Water with Triton X-100 Surfactant: Excited-State Properties with Femtosecond Resolution

Stable Charge-Transfer Complexes versus Contact Complexes. Application to the Interaction of Fullerenes with Aromatic Hydrocarbons

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Photophysical Properties of C₆₀ Colloids Suspended in Water with Triton X-100 Surfactant: Excited-State Properties with Femtosecond Resolution