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초록

BF2-chelated dipyrromethenes (BODIPYs) were integrated into cycloparaphenylene (CPP) rings via two different connection modes for the first time. Singlecrystal X-ray diffractions revealed that the 2,6-connected BODIPY-CPP ring (1) exhibited a classical H & uuml;ckel topology with a bending BODIPY unit; however, two conformers of the 3,5-connected BODIPYCPP ring (2) were observed in the solid state, of which one exhibited a M & ouml;bius topology. Both nanorings exhibited largely redshifted absorption and emission, compared to the single BODIPY chromophore and conventional CPP nanorings. Femtosecond transient absorption measurements were performed to elucidate the intramolecular charge transfer (ICT) processes of both nanorings. In 1, ICT occurred before transitioning to the triplet state, whereas in 2, the relaxation process followed ICT; moreover, the quenching dynamics between the two nanorings and quencher p-chloranil (Q) were investigated. Only dynamic quenching was observed in the H & uuml;ckel structure of 1, whereas that of 2 exhibited both dynamic and static quenching. These findings indicate that the differences in the molecular topologies of the BODIPY-integrated carbon nanorings contributed significantly to determining their electronic structures, photophysical properties, and quenching behavior towards external quencher. Our study thus provides new insights into the design of advanced BODIPYand CPP-based materials with prospective applications.

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