Symmetry-Breaking Charge Separation Mediated Triplet Population in a Perylenediimide Trimer at the Single-Molecule Level

The Journal of Physical Chemistry Letters, Год журнала: 2024, Номер 15(22), С. 5896 - 5904

Опубликована: Май 28, 2024

Herein, we demonstrate triplet excited-state population in a conformationally rigid perylenediimide trimer (PDI-T) via intramolecular symmetry-breaking charge separation (SB-CS) at the single-molecule level. The fluorescence intensity trajectories of PDI-T nonpolar polystyrene matrix (ε = 2.60) exhibit prolonged with infrequent dark states, representing and/or transfer states. In contrast, poly(vinyl alcohol) 7.80), erratic blinking dynamics resulting low photon counts were observed, corroborating feasibility polar environment. agreement measurements, transient absorption spectroscopy reveals ultrafast SB-CS (τCS < 5 ps) tetrahydrofuran 7.58) and acetone 20.70), through recombination. current investigation shows utility weakly coupled molecular constructs controlling generation for potential applications optoelectronic devices.

Язык: Английский

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The literature of heterocyclic chemistry, part XXII, 2022

Advances in heterocyclic chemistry, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Язык: Английский

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Symmetry Breaking Charge Separation in Linked Violanthrone Dimers

Chemical Communications, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Symmetry-breaking charge separation (SBCS) has the potential to significantly enhance energy conversion efficiency. However, role of molecular structure in mediating SBCS remains incompletely understood. Here, we report novel violanthrone dimers where transfer (CT) and (CS) is tunable through design. We show that polar environments CT readily occurs even at large interchromophore distances with flexible linkers. While character observed all studied, CS most for dimer shortest separation.

Язык: Английский

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Modulating the Charge Transfer Coupling in Boron-Dipyrromethene Homodimers by π-Bridge Units

The Journal of Physical Chemistry B, Год журнала: 2025, Номер unknown

Опубликована: Март 19, 2025

To mimic the excitation energy conversion mechanisms observed in natural light-harvesting systems, we have extensively investigated photoinduced symmetry-breaking charge separations (SBCSs) various multichromophoric model systems been investigated. However, designing capable of simultaneously achieving ultrafast and complete SBCS remains a significant challenge. In this study, employed benzene, thiophene, furan as π-bridges to develop series boron dipyrromethene (BODIPY) homodimers. Spectral analysis, together with an estimation π-bridge-dependent transfer (CT) coupling using fragment difference method, reveals that π-bridge units different electron-donating abilities can effectively modulate CT between chromophores. Notably, furan-based π-bridge, exhibiting most pronounced character, facilitates (SBCT), i.e., excimer formation time constant about 12 ps weak polar toluene. Furthermore, dramatic increase rate was highly acetonitrile, improving from 60.4 for benzene-bridged homodimer 2.9 furan-bridged counterpart. These findings underscore potential tuning photophysical properties covalent molecular aggregates by optimizing such specific applications organic photovoltaics photocatalysis.

Язык: Английский

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Intramolecular Singlet Fission in Individual Graphene Nanoribbons─Competition with a Charge Transfer

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 19, 2025

Graphene nanoribbons (NRs) constitute a versatile platform for developing novel materials, where their structure governs optical, electronic, and magnetic properties while also shaping excited-state dynamics. Here, we investigate set of three twisted N-doped molecular NRs increasing length, obtained by linearly fusing perylene diimide to pyrene pyrazino- or thiadiazolo-quinoxaline residues. By employing various temperature-dependent time-resolved spectroscopy techniques, reveal how the flexible NR geometry promotes formation mixed electronic state with varying contributions from locally excited charge-transfer (CT) states. The fate this is highly sensitive geometry, solvent polarity. For shortest NR, intersystem crossing dominates deactivation pathway, efficiently generating triplets in low-polarity solvents. In contrast, extended NRs, intramolecular singlet fission (SF) takes place within single nanoribbon. This enabled enhanced superexchange coupling due pronounced push-pull nature existence multiple localized π-electron states caused heteroatom doping, thereby circumventing need dimeric interactions typically associated conventional SF systems. higher-polarity environments, evidence (diabatic) CT emerges. These findings underscore intricate relationship between energy levels, dynamics NRs.

Язык: Английский

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A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(12)

Опубликована: Янв. 26, 2023

We report a long-lived charge-separated state in chromophoric pair (DC-PDI2 ) that uniquely integrates the advantages of fundamental processes photosynthetic reaction centers: i) Symmetry-breaking charge-separation (SB-CS) and ii) Marcus-inverted-region dependence. The near-orthogonal bichromophoric DC-PDI2 manifests an ultrafast evolution SB-CS with time constant τSB-CS${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps slow charge recombination (CR) kinetics τCR${{\tau R}}}$ =4.09±0.01 ns ACN. rate CR is 11 686 times slower than ACN, as PDI radical ion-pair occurs deep inverted region Marcus parabola ( -ΔGCR${{-{\rm \Delta }G}_{{\rm >λ). In contrast, analogous benzyloxy (BnO)-substituted DC-BPDI2 showcases ≈10-fold accelerated τCR/τSB-CS${{\tau R}}/{\tau lowering to ≈1536 by virtue decreased driving force. present investigation demonstrates control molecular engineering tune energetics material, which essential for next-generation optoelectronic devices.

Язык: Английский

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Spin–orbit charge-transfer intersystem crossing in heavy-atom-free orthogonal covalent boron-dipyrromethene heterodimers

Physical Chemistry Chemical Physics, Год журнала: 2023, Номер 25(36), С. 24386 - 24394

Опубликована: Янв. 1, 2023

Boron-dipyrromethene (BODIPY) derivatives are prospective organic-based triplet photosensitizers. Since the generation yield of parent BODIPY is low, heavy atoms widely used to improve yield. However, dimerization BODIPYs can also significantly their ability produce triplets. Through a comparative study formation dynamics two heavy-atom-free orthogonal covalent heterodimers that differ in dihedral angles, we have demonstrated mechanism spin-orbit charge-transfer intersystem crossing (SOCT-ISC) promotes solution. Different from general understanding SOCT-ISC, heterodimer with smaller angle and low structural rigidity showed better due (a) stronger inter-chromophoric interaction heterodimer, which promoted solvent-stabilized (CT) state, (b) more favorable energy level alignment sizeable coupling strength, (c) balance between stabilized singlet CT state limited direct charge recombination ground weakly polar solvent. The complete spectral characterization clarified SOCT-ISC important factors affecting heterodimers.

Язык: Английский

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Ultrasmall Organic Nanocrystal Photocatalyst Realizing Highly Efficient Symmetry Breaking Charge Separation and Transport

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Апрель 7, 2025

The high exciton binding energy and short diffusion length (typical 5-10 nm) of organic photocatalysts (OPCs) hinder efficient charge separation subsequent transfer, limiting their potential for solar conversion. Inspired by the symmetry breaking (SBCS) in natural photosystem II, we employed a freeze assembly (FA) strategy to assemble symmetric perylene diimide (PDI) dimers into ultrasmall (sub-5 nanocrystals (NCs) with ordered molecular stacking, exhibiting SBCS characteristics. NCs (p-5 showed 12.3-fold enhancement efficiency compared non-SBCS (PDI-5 nm). Furthermore, transfer p-5 nm (94.7%) was 1.6 times greater than that weak (m-5 nm, 60.4%). Consequently, achieved comparable photocatalytic hydrogen evolution rate (1824 μmol h-1 g-1) among PDI-based nm. This study highlights importance fulfilling bioinspired FA developing high-performance OPCs.

Язык: Английский

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A Light-Responsive Metal–Organic Framework with Perchlorinated Nanographene Ligands

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Май 4, 2025

Harnessing water as a sustainable electron source for artificial photosynthesis remains significant challenge. This work presents Alice-MOF-1, novel zirconium metal-organic framework (MOF) incorporating hexatopic ligands with perchlorinated hexa-peri-hexabenzocoronene (HBC) core, photocatalyst CO2 reduction using the terminal donor. Contortion of ligand, induced by edge chlorination, minimizes π-stacking and enhances solubility, enabling direct MOF synthesis. The controlled arrangement chromophores within Alice-MOF-1 is crucial complex multielectron redox reactions. unique ligand architecture promotes symmetry-breaking charge transfer (SBCT), mechanism observed in natural photosynthesis, leading to efficient separation minimal energy loss. Femtosecond transient absorption spectroscopy time-resolved paramagnetic resonance (EPR) confirm formation long-lived radical ions, providing evidence SBCT negligible recombination. These findings demonstrate power MOF-based chromophore assemblies mimic nature's light-harvesting strategies conversion.

Язык: Английский

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Direct Observation of Ultrafast Relaxation Dynamics of a Mixed Excimer State in Perylene Monoimide Dimer by Femtosecond Transient Absorption

The Journal of Physical Chemistry Letters, Год журнала: 2023, Номер 14(10), С. 2455 - 2462

Опубликована: Март 3, 2023

A J-type dimer PMI-2, two perylene monoimides linked by butadiynylene bridger was prepared, and its excited-state dynamics studied using ultrafast femtosecond transient absorption spectroscopy, along with steady-state spectroscopy quantum chemical calculations. It is evidently demonstrated that the symmetry-breaking charge separation (SB-CS) process in PMI-2 positively mediated an excimer, which mixed localized Frenkel excitation (LE) interunit transfer (CT) state. Kinetic studies show that, polarity increasing of solvent, transformation excimer from a mixture to CT state accelerated, recombination time reduced obviously. Theoretical calculations indicate these are due obtaining more negative free energy (ΔGcs) lower levels highly polar solvents. Our work suggests can be formed suitable structure, sensitive solvent environment.

Язык: Английский

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