Direct observation of chirality-induced spin selectivity in electron donor–acceptor molecules

Science, Год журнала: 2023, Номер 382(6667), С. 197 - 201

Опубликована: Окт. 12, 2023

The role of chirality in determining the spin dynamics photoinduced electron transfer donor-acceptor molecules remains an open question. Although chirality-induced selectivity (CISS) has been demonstrated bound to substrates, experimental information about whether this process influences themselves is lacking. Here we used time-resolved paramagnetic resonance spectroscopy show that CISS strongly isolated covalent donor-chiral bridge-acceptor (D-Bχ-A) which selective photoexcitation D followed by two rapid, sequential electron-transfer events yield D•+-Bχ-A•-. Exploiting phenomenon affords possibility using chiral molecular building blocks control states quantum applications.

Язык: Английский

---

Singlet‐Triplet Energy Inversion in Carbon Nitride Photocatalysts

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(48)

Опубликована: Окт. 6, 2023

Abstract Time‐resolved EPR (TR‐EPR) demonstrates the formation of well‐defined spin triplet excitons in carbon nitride. This permits to experimentally probe extent wavefunction which delocalizes over several tri‐ s ‐triazine units. Analysis temperature dependence TR‐EPR signal reveals mobility excitons. By employing monochromatic light excitation range 430–600 nm, energy is estimated be ≈0.2 eV above conduction band edge, proving that exciton lies corresponding singlet. Comparison between amorphous and graphitic forms establishes singlet‐triplet inversion as a general feature nitride materials.

Язык: Английский

---

Controlling Intramolecular Singlet Fission Dynamics via Torsional Modulation of Through-Bond versus Through-Space Couplings

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(38), С. 20883 - 20896

Опубликована: Сен. 14, 2023

Covalent dimers, particularly pentacenes, are the dominant platform for developing a mechanistic understanding of intramolecular singlet fission (iSF). Numerous studies have demonstrated that photoexcited state in these structures can rapidly and efficiently undergo exciton multiplication to form correlated pair triplets within single molecule, with potential applications from photovoltaics quantum information science. One most significant barriers limiting such dimers is fast recombination triplet pair, which prevents spatial separation formation long-lived states. There an ever-growing need develop general synthetic strategies control evolution following iSF enhance their lifetime. Here, we rationally tune dihedral angle interchromophore between pairs pentacenes systematic series bridging units facilitate separation. Through combination transient optical spin-resonance techniques, demonstrate torsion linker provides simple handle fine balance through-bond through-space couplings steer iSF. We show full pathway femtosecond microsecond timescales tuned through static coupling set by molecular design structural fluctuations be biased steric control. Our approach highlights straightforward principle generate paramagnetic spin states higher yields.

Язык: Английский

---

PDI–trityl dyads as photogenerated molecular spin qubit candidates

Chemical Science, Год журнала: 2023, Номер 14(39), С. 10727 - 10735

Опубликована: Янв. 1, 2023

Owing to their potential applications in the field of quantum information science, photogenerated organic triplet-radical conjugates have attracted an increasing amount attention recently. Typically, these compounds are composed a chromophore appended stable radical. After initialisation system by photoexcitation, highly spin-polarised quartet state may be generated, which serves as molecular spin qubit candidate. Here, we investigate three perylene diimide (PDI)-based chromophore-radical systems with different phenylene linkers and radical counterparts both optical spectroscopy transient electron paramagnetic resonance (EPR) techniques. Femtosecond absorption measurements demonstrate triplet formation on picosecond time scale for PDI-trityl dyads, while excited deactivation is found slowed down considerably PDI-nitroxide analogue. The subsequent investigation coherent properties EPR confirms triplet-doublet mixing all investigated dyads suitability two studied candidates. In particular, show that using tetrathiaryl trityl counterpart, intense polarisation observed even at room temperature coherence times 3.0 μs can achieved 80 K, represents considerable improvement compared previously systems.

Язык: Английский

---

Oriented Triplet Excitons as Long-Lived Electron Spin Qutrits in a Molecular Donor–Acceptor Single Cocrystal

Journal of the American Chemical Society, Год журнала: 2023, Номер 146(1), С. 1089 - 1099

Опубликована: Дек. 29, 2023

The photogeneration of multiple unpaired electron spins within molecules is a promising route to applications in quantum information science because they can be initialized into well-defined, multilevel states (S > 1/2) and reproducibly fabricated by chemical synthesis. However, coherent manipulation these spin difficult realize typical molecular systems due the lack selective addressability short coherence times transitions. Here, challenges are addressed using donor–acceptor single cocrystals composed pyrene naphthalene dianhydride host spatially oriented triplet excitons, which exhibit photogenerated qutrit properties. Time-resolved paramagnetic resonance (TREPR) spectroscopy demonstrates that orienting excitons crystal platform imparts narrow, well-resolved, tunable resonances EPR spectrum, allowing sublevel Pulse-EPR reveals at temperatures above 30 K, decoherence driven exciton diffusion. limited electronic dipolar coupling below where T2 varies nonlinearly with optical excitation density annihilation. Overall, an optimized time = 7.1 μs 20 K achieved. These results provide important insights designing solid-state excitonic materials improved

Язык: Английский

---

Structure-Dependent Triplet State Formation in Fluorinated Perylenediimide Single Crystal Polymorphs

The Journal of Physical Chemistry C, Год журнала: 2024, Номер 128(4), С. 1603 - 1611

Опубликована: Янв. 17, 2024

Perylenediimide (PDI) and its derivatives have garnered significant attention as promising n-type semiconductors to replace fullerenes acceptors in organic photovoltaic cells (OPVs). However, the aggregation tendencies rapid excimer formation of PDIs hindered their efficiency OPVs. To address this issue enhance solubility while fine-tuning electronic properties, researchers explored fluorination strategies. In study, we investigate structure–function relationship two crystalline N,N-bis(2′,2′,3′,3′,4′,4′,5′,5′,6′,6′,7′,7′,8′,8′,8′-pentadecafluorooctan-1-yl)perylene(3,4:9,10)bis(dicarboximide) (FPDI) polymorphs, namely, FPDI-α FPDI-β. Their crystal structures show that π systems FPDI molecules adopt an orthogonal geometry, those FPDI-β are parallel slip-stacked. We report excited state dynamics using transient absorption fluorescence microscopy time-resolved electron paramagnetic resonance spectroscopy. Upon photoexcitation, both polymorphs exhibit a lowest singlet (S1) with substantial charge transfer (CT) character. This S1-CT decays τ = 350 ps form triplet via spin–orbit charge-transfer intersystem crossing near-quantitative yield, back ground 140 ps. study illustrates influence different packing motifs on photoinduced intermolecular CT processes single crystals same molecule contributes understanding role optimizing PDI-based molecular materials for solid state.

Язык: Английский

---

Metalloporphyrins as Building Blocks for Quantum Information Science

Advanced Optical Materials, Год журнала: 2024, Номер 12(18)

Опубликована: Май 17, 2024

Abstract The intrinsic quantum nature of molecules opens exciting opportunities for developing the field information science. In this context, porphyrins stand out as ideal building blocks technologies thanks to their unique optical and electrical properties well capacity accommodate metal atoms ions. This review bridges chemistry physics porphyrins, providing an overview recent advances in porphyrin‐based molecular qubits. Starting from qubits, explores potential porphyrin units combine, leading formation logic gates hierarchical higher‐dimensional structures. Next, exploitation porphyrins' photophysical realizing long‐lived high spin states is examined. These are promising photogeneration multi‐level systems initialization control With a critical eye on current state‐of‐the‐art, elucidates future perspectives advancing technologies.

Язык: Английский

---

Luminescent Organic Triplet Diradicals as Optically Addressable Molecular Qubits

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Сен. 27, 2024

Optical-spin interfaces that enable the photoinitialization, coherent microwave manipulation, and optical read-out of ground state spins have been studied extensively in solid-state defects such as diamond nitrogen vacancy (NV) centers are promising for quantum information science applications. Molecular bits (qubits) offer many advantages over spin through synthetic control their properties scalability into well-defined multiqubit arrays. In this work, we report an optical-spin interface organic molecular qubit consisting two luminescent tris(2,4,6-trichlorophenyl)methyl (TTM) radicals connected via

Язык: Английский

---

Room-Temperature Optical Spin Polarization of an Electron Spin Qudit in a Vanadyl-Free Base Porphyrin Dimer

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Дек. 16, 2024

Photoexcited organic chromophores appended to molecular qubits can serve as a source of spin initialization or multilevel qudit generation for quantum information applications. So far, this approach has been primarily investigated in chromophore–stable radical systems. Here, we extend concept meso-meso linked oxovanadium(IV) porphyrin–free-base porphyrin dimer. Femtosecond transient absorption experiments reveal that photoexcitation the free-base leads picosecond triplet state formation via enhanced intersystem crossing. Time-resolved electron paramagnetic resonance (TREPR) carried out at both 85 K and room temperature long-lived spin-polarized quartet through triplet–doublet mixing. Notably, distinct hyperfine structure arising from interaction between vanadyl nucleus (51V, I = 7/2) is evident, with showing polarization even temperature. Theoretical simulations TREPR spectra confirm photogenerated provide insights into non-Boltzmann populations. Exploiting phenomenon affords possibility using photoinduced states porphyrins resource polarize magnetically couple electronic nuclear qudits.

Язык: Английский

---

Influence of the substitution position on spin communication in photoexcited perylene–nitroxide dyads

Chemical Science, Год журнала: 2024, Номер 15(20), С. 7515 - 7523

Опубликована: Янв. 1, 2024

Photoexcited chromophore–radical dyads are suitable for applications in molecular spintronics. We show that the position of attachment radical to chromophore can be used as a means tune their optical and magnetic properties.

Язык: Английский

---