Indexed by:期刊论文

Date of Publication:2018-01-11

Journal:JOURNAL OF PHYSICAL CHEMISTRY C

Included Journals:SCIE、EI

Volume:122

Issue:1

Page Number:185-193

ISSN No.:1932-7447

Abstract: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%.