Hongli Xue, Changqing Ye, Haiyang Huang, Hongli Bao
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Steric Gating of Excited-State Channel: Controllable AIE/RTP Switching through Tuning π-Bond Twisting.
We demonstrate steric control of excited-state channel in π-conjugated 1,1'-bibenzo[f]isoindolylidenes through substituent-engineered C═C bond twisting. By tuning substituent bulkiness (R2), we achieve dynamic switching between aggregation-induced emission and dilute/dual-state fluorescence. The mechanical gating of biradicaloid isomerization channels was confirmed by variable-temperature NMR and EPR spectroscopy. The π-twisting activates low-energy CI pathways for AIE generation, while excessive bulkiness relocks molecular conformation, enabling solution-phase emission. This steric gating mechanism, validated by TD-DFT analysis, demonstrates controllable fluorescence and phosphorescence by modulating the π-twisting feasibility of the central C═C bond, offering a novel strategy for designing advanced aggregation-induced emission (AIE) and RTP-active molecules.
期刊介绍：
Organic Letters invites original reports of fundamental research in all branches of the theory and practice of organic, physical organic, organometallic,medicinal, and bioorganic chemistry. Organic Letters provides rapid disclosure of the key elements of significant studies that are of interest to a large portion of the organic community. In selecting manuscripts for publication, the Editors place emphasis on the originality, quality and wide interest of the work. Authors should provide enough background information to place the new disclosure in context and to justify the rapid publication format. Back-to-back Letters will be considered. Full details should be reserved for an Article, which should appear in due course.
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