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论文类型：期刊论文

发表时间：2018-01-11

发表刊物：JOURNAL OF PHYSICAL CHEMISTRY C

收录刊物：SCIE、EI

卷号：122

期号：1

页面范围：185-193

ISSN号：1932-7447

摘要：It is well-known that the fluorescence of a chromophore can be efficiently quenched by the free rotor effect, sometimes called intramolecillar rotation (IMR), i.e. by a large-amplitude torsional motion. Using this effect, aggregation induced enhanced emission (AIE) and fluorescent molecular probes for viscosity measurements have been devised. However, the rotor effect on triplet excited states was rarely studied. Herein, with molecular rotors of Bodipy and diiodoBodipy, and by using steady state and time resolved transient absorption/emission spectroscopies, we confirmed that the triplet excited state-of the Bodipy chromophore is not quenched by IMR. This is in stark contrast to the fluorescence (singlet excited state), which is significantly quenched by IMR. This result is rather interesting since a long-lived excited state (triplet, 276 mu s) is not quenched by the IMR, but the short-lived excited state (singlet, 3.8 ns) is quenched by the same IMR The unquenched triplet excited state of the Bodipy was used for triplet-triplet annihilation upconversion, and the upconversion quantum yield is 6.3%.