Generation of long-lived radical ions through enhanced photoinduced electron transfer processes between [60]fullerene and phenothiazine derivatives

Sasaki, Yoshiko; Araki, Yasuyuki; Ito, Osamu; Alam, Maksudul M.

doi:10.1039/b617229f

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…Heterogeneous host systems provide much better environment than homogeneous solution systems and the photoinduced radicals are typically more stable in solid systems. Photoionization of phenothiazine and derivatives was carried out in numerous media like micelles, 4 vesicles, silica gel, 5 fullerene, 6 microporous 7 as well as mesoporous [8][9][10][11][12][13] molecular sieves. To date, N-alkylphenothiazines proved to be excellent photoactive electron donor molecules and were extensively studied as a function of the alkyl chain length and of pore size.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous charge separation induced by phenothiazine sorption within acidic HnZSM-5

Moissette¹,

Luchez²,

Brémard³

et al. 2009

Phys. Chem. Chem. Phys.

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In situ diffuse reflectance UV-visible, Raman scattering and EPR experiments, carried out as a function of time after phenothiazine (PTZ) direct exposure to thermally activated acid H(n)ZSM-5 zeolite without any solvent, provide evidence of phenothiazine sorption and simultaneous spontaneous ionization. For comparison, phenothiazine behavior was investigated within non acidic zeolite and showed that most of the phenothiazine molecules were occluded as intact molecules and that ionization was very weak. The multivariate curve resolution analysis of the diffuse reflectance UV-visible spectra set recorded during the sorption process resolve the absorption spectra and respective concentrations of individual species involved in the sorption course. When PTZ entered through the acidic zeolite channels, PTZ (+)@H(n)ZSM-5 (-) radical pair is generated by the polarization energy. Subsequent PTZ(2+) formation was fast but only partial. After months, equilibrium including PTZ (+), PTZ(2+) and occluded PTZ was reached within acid H(n)ZSM-5 but depends on the Si/Al ratio: the higher the Al content, the easier the spontaneous ionization. The close match between PTZ and the pore size of zeolites combined with efficient polarizing effect of proton and aluminium electron trapping sites appear to be the most important factors responsible for the stabilization of PTZ (+) and PTZ(2+) and hinder efficiently the charge recombination. No evidence of Brønsted acid sites of H(n)ZSM-5 was found during the sorption of phenothiazine through generation of protonated species.

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Section: Introductionmentioning

confidence: 99%

Spontaneous charge separation induced by phenothiazine sorption within acidic HnZSM-5

Moissette¹,

Luchez²,

Brémard³

et al. 2009

Phys. Chem. Chem. Phys.

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“…[17][18][19][20] Furthermore, intermolecular ET via 3 C 60 * has been reported for PTZ derivatives. 21,22 Intramolecular CS processes have also been reported in polar solvent for C 60 -phenothiazine dyads bridged by flexible linkers; 23 the contribution of CS via the 3 C 60 * was studied under magnetic field.…”

Section: Introductionmentioning

confidence: 99%

“…Phenothiazine derivatives are well-known heterocyclic compounds with high electron-donor ability because of their eight (π + n)-electrons in the central ring. , Molecules and polymers containing a phenothiazine (PTZ) moiety have recently attracted much interest in materials science, because of their potential applicability as electroluminescent and photovoltaic cells. – Furthermore, intermolecular ET via 3 C 60 * has been reported for PTZ derivatives. , Intramolecular CS processes have also been reported in polar solvent for C 60 −phenothiazine dyads bridged by flexible linkers; the contribution of CS via the 3 C 60 * was studied under magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Charge-Separation and Charge-Recombination Processes of Fullerene[60] Dyads Covalently Connected with Phenothiazine and Its Trimer

et al. 2008

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Photoinduced charge-separation and charge-recombination processes of fullerene[60] dyads covalently connected with phenothiazine and its trimer (PTZ n -C 60, n = 1 and 3) with a short amide linkage were investigated. A time-resolved fluorescence study provided evidence of charge separation via the excited singlet state of a C 60 moiety ( (1)C 60*), which displayed high efficiencies in various solvents; Phi (S) CS (quantum yield of charge separation via (1)C 60*) = 0.59 (toluene) to 0.87 (DMF) for PTZ 1-C 60 and 0.78 (toluene) to 0.91 (DMF) for PTZ 3-C 60. The transient absorption measurement with a 6 ns time resolution in the visible and near-IR regions showed evidence of the generation of radical ion pairs in relatively polar solvents for both dyads. In nonpolar toluene, only PTZ 1- (3)C 60* was observed for PTZ 1-C 60, whereas PTZ 3- (3)C 60* as well as the radical ion pair state in equilibrium were observed for PTZ 3-C 60. The radical ion pairs had relatively long lifetimes: 60 (DMF) to 910 ns ( o-dichlorobenzene) for (PTZ) 1 (*+)-C 60 (*-) and 230 (PhCN) to 380 ns ( o-dichlorobenzene) for (PTZ) 3 (*+)-C 60 (*-). The small reorganization energy (lambda) and the electronic coupling element (| V|) were estimated by the temperature dependence of the charge-recombination rates, i.e., lambda = 0.53 eV and | V| = 1.6 cm (-1) for (PTZ) 3 (*+)-C 60 (*-).

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“…The simulation of relevant processes has reached a high level of understanding and the primary process of light-induced charge separation in various types of Do–Acc dyads has been intensively studied [28–29]. This photo-induced electron transfer (PET) [30–34] has been investigated with donors such as porphyrines, polycyclic aromatic hydrocarbons, perylenediimides and (oligo)thiophenes [35–36], tetrathiafulvalenes [37], as well as phenothiazine and its derivatives [22,38–40]. The latter have become attractive electrophores due to their reversible and tunable oxidation potential.…”

Section: Introductionmentioning

confidence: 99%

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

Bay¹,

Makhloufi²,

Janiak³

et al. 2014

Beilstein J. Org. Chem.

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SummaryPhenothiazinyl and carbazolyl-donor moieties can be covalently coupled to an anthraquinone acceptor unit through an Ugi four-component reaction in a rapid, highly convergent fashion and with moderate to good yields. These novel donor–acceptor dyads are electronically decoupled in the electronic ground state according to UV–vis spectroscopy and cyclic voltammetry. However, in the excited state the inherent donor luminescence is efficiently quenched. Previously performed femtosecond spectroscopic measurements account for a rapid exergonic depopulation of the excited singlet states into a charge-separated state. Calculations of the Gibbs energy of photo-induced electron transfer from readily available UV–vis spectroscopic and cyclovoltammetric data applying the Weller approximation enables a quick evaluation of these novel donor–acceptor dyads. In addition, the X-ray structure of a phenothiazinyl–anthraquinone dyad supports short donor–acceptor distances by an intramolecular π-stacking conformation, an important assumption also implied in the calculations of the Gibbs energies according to the Weller approximation.

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Generation of long-lived radical ions through enhanced photoinduced electron transfer processes between [60]fullerene and phenothiazine derivatives

Cited by 12 publications

References 26 publications

Spontaneous charge separation induced by phenothiazine sorption within acidic HnZSM-5

Spontaneous charge separation induced by phenothiazine sorption within acidic HnZSM-5

Photoinduced Charge-Separation and Charge-Recombination Processes of Fullerene[60] Dyads Covalently Connected with Phenothiazine and Its Trimer

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

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