Use of Transient EPR Spectroscopy of Excited Triplet State for the Structural Assignment of Bisadducts of Fullerene C<sub>60</sub>

Pasimeni, Luigi; Hirsch, Andreas; Lamparth, Iris; Herzog, Andrea; Maggini, Michele; Prato, Maurizio; Corvaja, Carlo; Scorrano, Gianfranco

doi:10.1021/ja9709583

Cited by 64 publications

(66 citation statements)

References 28 publications

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“…This means in principle polarization could be achieved by orienting the molecules in a crystal. The electron spin echodetected spectra revealed no change in the line shape as a function of excitation delay time or temperature in the PRL [20]. To determine absolute populations and triplet decay rates for the three sublevels we investigated the relaxation kinetics (Fig.…”

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confidence: 99%

Entangling Remote Nuclear Spins Linked by a Chromophore

et al. 2010

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Molecular nanostructures may constitute the fabric of future quantum technologies, if their degrees of freedom can be fully harnessed. Ideally one might use nuclear spins as low-decoherence qubits and optical excitations for fast controllable interactions. Here, we present a method for entangling two nuclear spins through their mutual coupling to a transient optically excited electron spin, and investigate its feasibility through density-functional theory and experiments on a test molecule. From our calculations we identify the specific molecular properties that permit high entangling power gates under simple optical and microwave pulses; synthesis of such molecules is possible with established techniques. DOI: 10.1103/PhysRevLett.104.200501 PACS numbers: 03.67.Bg, 03.67.Lx, 31.15.EÀ, 33.40.+f Molecules are promising building blocks for quantum technologies, due to their reproducible nature and ability to self-assemble into complex structures. However, the need to control interactions between adjacent qubits represents a key challenge [1][2][3][4]. We here describe a method for optical control of a nuclear spin-spin interaction that presents several advantages over conventional NMR quantum processors: the spin-spin interaction can be switched, the gates are faster, and the larger energy transitions facilitate polarization transfer onto the nuclear spins. After explaining the theory behind our method, we present an experimental study of a test molecule, and show with density-functional theory that an entangling gate could be achieved.We consider two nuclear spin qubits labeled n and n 0 and one mediator e. The mediator possesses a paramagnetic excited state jei with spin one character and a diamagnetic, spinless ground state j0i. The two nuclear qubits do not interact with each other directly, but both couple to the excitation via an isotropic hyperfine (HF) coupling with generally unequal strengths A and A 0 , see Fig. 1(a). The Hamiltonian in a magnetic field is given by (@ ¼ 1):where S z;i and S i are the Pauli spin operators and ! i denotes the respective Zeeman splittings (i ¼ n, n 0 , e). D is the zero-field-splitting (ZFS). ! 0 denotes the optical frequency corresponding to the creation energy of the excitation. Let us first analyze the case of a symmetric (homonuclear) system with ! n ¼ ! n 0 and A ¼ A 0 . Using degenerate perturbation theory and assuming that the electronic Zeeman splitting is much larger than that of the nuclei, ! n ( ! e and the ZFS, D ( ! e , we obtain an effective Hamiltonian by approximating H sym : ¼ hejHjei; thus,where V ¼ ðjc 1 ijc 2 i Á Á Á jc 12 iÞ is the matrix of the approximate eigenvectors up to first order and the E i (i ¼ 1; . . . ; 12) are the eigenenergies up to second order. This reveals that the time evolution of the entire system can be

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confidence: 99%

Entangling Remote Nuclear Spins Linked by a Chromophore

et al. 2010

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“…[16] In the case of stepwise bis-addition to C 60 through the 1,3-dipolar cycloaddition to yield bis(N-methylpyrrolidine) adducts, the yield of the trans-1 bis-adduct was 1.5 %. [17] To improve the yield of trans-1 bis-adducts of C 60 , the tether-directed remote-functionalization synthetic procedure introduced by Diederich et al has proved to be an effective alternative. [18] By using this method, they synthesized trans-1 bisadducts of C 60 in relatively high yields.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Fullerene Adducts with Terpyridyl‐ or Pyridylpyrrolidine Groups in trans‐1 Positions

Zhang

Lukoyanova

Echegoyen

2006

Chemistry A European J

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Two C(60) hexakis-adducts (2 and 3) were synthesized by using a protection-deprotection strategy. The symmetric fullerene tetrakis-adduct 8 was obtained by anthracene removal from the hexakis-adduct 7. Reaction of 8 with terpyridylglycine or pyridylglycine afforded two hexakis-adducts, 2 and 3. By using the retro-cyclopropanation reaction, the four malonate addends located on the equatorial belt of the hexakis-adducts were removed to afford two trans-1 bis-adducts, 4 and 5, with terpyridyl- or pyridylpyrrolidine groups. The structures of 2 and 3 were confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and (1)H, (13)C, and COSY NMR, and UV-visible spectroscopy. The cyclic voltammograms of fullerene multiadducts 2, 3, and 9 show irreversible reductions. Self-assembled monolayers (SAMs) of 1 and 3 were formed on gold surfaces through nitrogen adsorption. SAMs of 3 represent the first example of a fullerene hexakis-adduct formed on gold surfaces through nitrogen adsorption. Controlled potential electrolyses (CPE) were conducted to prepare trans-1 bis-adducts 4 and 5 modified with terpyridyl and pyridyl groups.

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“…2. Here the sign of D is assumed to be same with C 60 ðD < 0Þ [1] as already applied for the reported mono-adducts [4,5] based on similarity of the spectra. Here the T z sublevel is populated least from S 1 both in the monomer and dimer.…”

Section: Results and Interpretationmentioning

confidence: 99%

“…From the reported data and ours, D and E seem to vary slightly depending on a size of an attached ring and a bridged atom (C, N or O) in the ring. The adducts of six-and three-membered >C-rings provide D ¼ À0:294 [3] and )0.274 [5] GHZ, respectively. This seems to be consistent with expectation that the more stain in a ring induces the larger deviation from D (¼ À0:344 GHz) [22] of C 60 .…”

Section: Discussionmentioning

confidence: 99%

“…In fact, several interesting results are reported for excited triplet ðT 1 Þ C 60 by EPR; (1) the excitation is localized at some part (mostly near the equator) of whole moiety [1,2]. (2) The spin distribution varies slightly with addition of adduct depending on its position [3][4][5]. (3) The EPR spectrum changes dramatically with temperature even in solid reflecting averages over the states generated from the Jahn-Teller splitting [6,7].…”

Section: Introductionmentioning

confidence: 99%

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Direct observation of localized excitation in the lowest excited triplet state of fullerene dimers C120 and C120O by means of time-resolved electron paramagnetic resonance

Yamauchi

Funayama

Ohba

et al. 2002

Chemical Physics Letters

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Time-resolved EPR spectra were observed by means of the transient EPR technique for two kinds of fullerene dimers C 120 and C 120 O in the lowest excited triplet ðT 1 Þ states and compared with those of mono-adducts of fullerene ðC 60 Þ. It was found that zero-field splitting (zfs) parameters of both dimers are nearly the same as those of the monomers, indicating that the excitation is almost completely localized at one of the two fullerene units in the T 1 state. Ó

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Use of Transient EPR Spectroscopy of Excited Triplet State for the Structural Assignment of Bisadducts of Fullerene C₆₀

Cited by 64 publications

References 28 publications

Entangling Remote Nuclear Spins Linked by a Chromophore

Entangling Remote Nuclear Spins Linked by a Chromophore

Synthesis of Fullerene Adducts with Terpyridyl‐ or Pyridylpyrrolidine Groups in trans‐1 Positions

Direct observation of localized excitation in the lowest excited triplet state of fullerene dimers C120 and C120O by means of time-resolved electron paramagnetic resonance

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Use of Transient EPR Spectroscopy of Excited Triplet State for the Structural Assignment of Bisadducts of Fullerene C60

Cited by 64 publications

References 28 publications

Entangling Remote Nuclear Spins Linked by a Chromophore

Entangling Remote Nuclear Spins Linked by a Chromophore

Synthesis of Fullerene Adducts with Terpyridyl‐ or Pyridylpyrrolidine Groups in trans‐1 Positions

Direct observation of localized excitation in the lowest excited triplet state of fullerene dimers C120 and C120O by means of time-resolved electron paramagnetic resonance

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Use of Transient EPR Spectroscopy of Excited Triplet State for the Structural Assignment of Bisadducts of Fullerene C₆₀