Cucurbituril‐Mediated Stacking Mode Conversion of Noncovalent Dimer

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Abstract The precise control of the spatial arrangement of organic photoconductive molecules plays an essential role in the fields of optoelectronics and bio‐imaging. Herein, three rigid diphenylpyridine substituted toluene derivatives p ‐BPy, m ‐BPy, o ‐BPy with angles of 180, 120 and 60 degrees, are synthesized, respectively. The crystal structures reveal that both p ‐BPy and m ‐BPy are J‐aggregate mode, and m ‐BPy stacks in an antiparallel manner, while p ‐BPy is in the isotropically parallel. 2D nuclear magnetic resonance (2D NMR) experiments demonstrate that p ‐BPy and m ‐BPy still are J‐aggregate mode in aqueous solution, and o ‐BPy does not stack. Cucurbit[8]uril (CB[8]) can bind two p ‐BPy or m ‐BPy molecules expectedly in its cavity, and the former still is J‐aggregate like in the solid state and aqueous solution with fluorescence emission peak red‐shifts from 490 to 570 nm. Surprisingly, the stacking pattern of two m ‐BPy molecules in the CB[8] cavity changes from antiparallel to isotropic, resulting in excimer emission with a quantum yield increases significantly from 26.6% to 97.1%. This observation suggests that the cavity of CB[8] can mediate the stacking mode conversion of the noncovalent dimer m ‐BPy, and could be useful for the design of organic photoconductive molecules in the future.

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