Spin polarization and photoinduced electron transfer between ferrocene and fullerene derivatives containing a nitroxide group

Conti, Fosca; Corvaja, Carlo; Maggini, Michele; Piu, F.; Scorrano, Gianfranco; Toffoletti, Antonio

doi:10.1007/bf03162211

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…17 and 21, for FN we observe signatures of a polarized nitroxide radical S = 1/2 corresponding to the D S0 state and of the photo-excited Q T1 state. 17,21,23,24 These two components can be distinguished according to their g-factors and nitroxide hyperfine splittings and are also observed here in FN-1a and FN-2a ( Fig. 1 and Fig.…”

Section: Cw-transient and Pulse Epr Of Photoexcited Fnssupporting

confidence: 71%

“…According to the analysis of ref. 21, these changes of radical polarization in the D S0 state are due to the so-called reversed-quartet mechanism RQM, a process by which reverse intersystem crossing between Q T1 and D T1 is fully competitive with the decay of these states to the ground state D S0 and to spin lattice relaxation back to a Boltzmann distribution (see also Section Kinetics and radical polarization).…”

Section: Cw-transient and Pulse Epr Of Photoexcited Fnsmentioning

confidence: 99%

“…20 Besides, the photo-excited state properties of fullerene-nitroxide (FN) have been extensively investigated by Corvaja and coworkers. 17,[21][22][23] Scheme 1B illustrates a simplified electronic-state diagram of photo-excited FN. 22 The C 60 and nitroxide moieties of FN can be considered as two separate electronic entities with electronic excitation localized on the fullerene.…”

Section: Introductionmentioning

confidence: 99%

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Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives

Liu

Liou

Enkin

et al. 2017

Phys. Chem. Chem. Phys.

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We report on radical polarization and optically-driven liquid DNP using nitroxide radicals functionalized by photoexcitable fullerene derivatives. Pulse laser excitation of the fullerene moiety leads to transient nitroxide radical polarization that is one order of magnitude larger than that at the Boltzmann equilibrium. The life time of the radical polarization increases with the size of the fullerene derivative and is correlated with the electronic spin-lattice relaxation time T. Overhauser NMR signal enhancements of toluene solvent protons were observed under steady-state illumination, which replaced microwave irradiation.

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Section: Cw-transient and Pulse Epr Of Photoexcited Fnssupporting

confidence: 71%

Section: Cw-transient and Pulse Epr Of Photoexcited Fnsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives

Liu

Liou

Enkin

et al. 2017

Phys. Chem. Chem. Phys.

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“…The TR-EPR spectra of photoexcited 1 and 2 have been already described [11,15]. Figure 2 shows the 2-D time-resolved EPR signal of derivative 3 in toluene solution recorded at 220 K. It represents the variation of the EPR signal intensity with respect to magnetic field and time axes.…”

Section: Resultsmentioning

confidence: 99%

The sign of the exchange interaction between triplet excited fullerene and nitroxide free radicals

2000

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The sign of the exchange interaction J in a series of radical triplet pairs (RTPs), formed by a nitroxide free radical and a triplet excited fullerene, has been determined from the spin polarization of time-resolved electron paramagnetic resonance spectra. Radical and fullerene are linked together by covalent bonds in different geometries. It is shown that the sign of J depends on the overlap between the orbital of nitroxide unpaired electron and the LUMO of fullerene, which is singly occupied in the excited triplet state. When the overlap does not vanish, a negative contribution to J arises from the admixing of a charge transfer structure in the wave function of the excited doublet state D of the RTP, which does not take place in the excited quartet state Q. The mixing of D* and Q' states lowers the energy of the former spin state and gives antiferromagnetic coupling.

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“…Figure b shows the time‐resolved ESR spectrum of a quartet state with a fine‐structure splitting observed for tetraphenylporphilinato‐zinc(II) coordinated by p ‐pyridyl nitronyl‐nitroxide (Zn‐TTP‐nipy) diluted in a toluene glass matrix. Later, additional homologous systems have been also reported . Furthermore, Ishii et al.…”

Section: Excited‐state Dynamics Of Non‐luminescent π‐Radicalsmentioning

confidence: 97%

Excited‐State Dynamics of Non‐Luminescent and Luminescent π‐Radicals

Teki

2019

Chemistry A European J

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Recently,t he potentialu se of organic p-radicals and relateds pin systems has been expanded to modern technological applications. The unique excited-state dynamics of organic p-radicals can be useful to improvet he stability of photochemically unstable organic compounds, make the polarization transfer applicable to information technology,a nd achieve effective up-conversion of interest for luminescence bioimaging, amongo thers. Furthermore, highly luminescent stable p-radicalsh ave been recently reported, which are especially interesting fora pplication in organic light-emitting devices owing to their potentialt op rovide an internal quantum efficiency of 100 %. Thus,t he excited-state nature of stable p-radicalsa sw ell as the control of their excited-state spin dynamics are emerging topics both in terms of fundamental science and related technological applications. In this minireview,w ef ocus on the excited-state dynamics of both photostable non(weakly)-luminescent and luminescent p-radicals, which are opposites of each other.I n particular, we cover the following topics:1 )effective generation of high-spin photoexcited states and control of the excited-state dynamics by using non-luminescent p-radicals, 2) unique excited-state dynamics of luminescent p-radicals and radical excimers, and 3) applicationsu tilizing excitedstate dynamics of p-radicals.[a] Prof.

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Spin polarization and photoinduced electron transfer between ferrocene and fullerene derivatives containing a nitroxide group

Cited by 16 publications

References 20 publications

Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives

Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives

The sign of the exchange interaction between triplet excited fullerene and nitroxide free radicals

Excited‐State Dynamics of Non‐Luminescent and Luminescent π‐Radicals

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