TY - JOUR
T1 - Stepwise decrease of fluorescence versus sequential photobleaching in a single multichromophoric system
AU - Issac, Abey
AU - Hildner, Richard
AU - Hippius, Catharina
AU - Würthner, Frank
AU - Köhler, Jürgen
PY - 2014/2/25
Y1 - 2014/2/25
N2 - For individual molecules from the newly synthesized calix[4]arene tethered perylene bisimide (PBI) trimer, we studied the emitted fluorescence intensity as a function of time. Owing to the zigzag arrangement of PBI dyes in these trimers, the polarization state of the emission provides directly information about the emitting subunit within the trimer. Interestingly, we observed emission from all neutral subunits within a trimer rather than exclusively from the subunit with the lowest site energy. This can be understood in terms of thermally activated uphill energy transfer that repopulates the higher energetic chromophores. Together with the simultaneously recorded polarization-resolved emission spectra, this reveals that the emission from a multichromophoric system is governed by a complex interplay between the temporal variations of the photophysical parameters of the subunits, bidirectional hopping processes within the trimer, and unavoidable photobleaching. Moreover, it is demonstrated that the typically observed stepwise decrease of the signal from a multichromophoric system does not necessarily reflect sequential bleaching of the individual chromophores within the macromolecule.
AB - For individual molecules from the newly synthesized calix[4]arene tethered perylene bisimide (PBI) trimer, we studied the emitted fluorescence intensity as a function of time. Owing to the zigzag arrangement of PBI dyes in these trimers, the polarization state of the emission provides directly information about the emitting subunit within the trimer. Interestingly, we observed emission from all neutral subunits within a trimer rather than exclusively from the subunit with the lowest site energy. This can be understood in terms of thermally activated uphill energy transfer that repopulates the higher energetic chromophores. Together with the simultaneously recorded polarization-resolved emission spectra, this reveals that the emission from a multichromophoric system is governed by a complex interplay between the temporal variations of the photophysical parameters of the subunits, bidirectional hopping processes within the trimer, and unavoidable photobleaching. Moreover, it is demonstrated that the typically observed stepwise decrease of the signal from a multichromophoric system does not necessarily reflect sequential bleaching of the individual chromophores within the macromolecule.
KW - excitation energy transfer
KW - multichromophore
KW - photobleaching
KW - polarization-resolved emission spectra
KW - single-molecule spectroscopy
KW - uphill energy transport
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U2 - 10.1021/nn4060946
DO - 10.1021/nn4060946
M3 - Article
C2 - 24444041
AN - SCOPUS:84894611175
SN - 1936-0851
VL - 8
SP - 1708
EP - 1717
JO - ACS Nano
JF - ACS Nano
IS - 2
ER -