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oai:figshare.com:article/34044094 2026-10-01T11:08:33Z category_1 category_4 category_915 category_24 category_873 portal_63 item_type_6 month_year_10_2026

Decoupling Electronic Coupling and Site-Energy Asymmetry in a Scaffold-Free π‑Assembly Yifei Wei (5263742) Jingjing Guo (393650) Yuchuan Xu (10491131) Wei Zhang (405) Xin-Yu Tong (8638809) Pavlo O. Dral (545078) WanZhen Liang (1463908) Yun-Bao Jiang (1351425) Dongho Kim (29790) Jianbin Lin (1940092) Hui-Jun Zhang (1415167) Biophysics Biochemistry Physical Sciences not elsewhere classified Evolutionary Biology Chemical Sciences not elsewhere classified ∼ 20 ns thus remains difficult spano vibronic analysis protein electrostatics ). preserving strong coupling photosynthetic special pairs photoluminescence show persistence like peripheral units facial packing maximizes (∼ 210 mev (∼ 12 mev opposing ct configurations free hierarchical π radiatively active excited directionally biased le electronic coupling (< decoupling electronic coupling structure calculations predict ct manifold predicted energy asymmetry (< state asymmetry yields ct </ sub le </ sub structure calculations state manifold 93 mev energy asymmetry conventional π >< sub observed excited lowest excited state ensemble state dynamics δε </ j </ c </ ≈ 0 In conventional π-stacked systems, electronic coupling (<i>J</i>) and site-energy asymmetry (<i>Δε</i>) are governed by the same structural coordinate. Co-facial packing maximizes <i>J</i> but enforces <i>Δε</i> ≈ 0, yielding symmetry-equivalent local-excitation-charge-transfer (LE-CT) manifolds near the charge-resonance/excimer limit, whereas chemically differentiated donor–acceptor systems impose <i>Δε</i> ≫ <i>J</i> and favor localized CT states. The intermediate regime, with finite static <i>Δε</i> while preserving strong coupling, thus remains difficult to access. Nature achieves this in photosynthetic special pairs by separating the structural origins of <i>J</i> (cofactor stacking) and <i>Δε</i> (protein electrostatics). Inspired by this principle, we construct a scaffold-free hierarchical π-assembly of four <i>C</i>₃-symmetric perylene diimide triads, which comprises strongly coupled dimeric cores and monomer-like peripheral units. Directional C–H···OC hydrogen bonding renders the core chromophores electronically inequivalent, producing static <i>Δε</i>_LE (∼12 meV) within a pair whose excitonic coupling, determined experimentally from a Spano vibronic analysis, is 93 meV. Electronic-structure calculations predict that this asymmetry is embedded in the lowest excited-state manifold at the Franck–Condon geometry, where the modest ground-state asymmetry yields a much larger <i>Δε</i>_CT (∼210 meV) splitting of opposing CT configurations. Femtosecond transient absorption resolves a 1.2 ps evolution toward increased ionic spectral character, while nanosecond spectroscopy and photoluminescence show persistence over ∼20 ns as a radiatively active excited-state ensemble. These results establish hierarchical self-assembly as a strategy for decoupling electronic coupling from site-energy asymmetry and provide a structural basis for a directionally biased LE-CT manifold predicted by electronic-structure calculations and consistent with the observed excited-state dynamics. 2026-10-01T00:00:00Z Text Journal contribution 10.1021/jacs.6c12873.s001 https://figshare.com/articles/journal_contribution/Decoupling_Electronic_Coupling_and_Site-Energy_Asymmetry_in_a_Scaffold-Free_Assembly/34044094 CC BY-NC 4.0