Photophysical Investigation of Cyano-Substituted Terrylenediimide Derivatives

Two new terrylenediimide (TDI) chromophores with cyano substituents in the bay and core area (BCN-TDI and OCN-TDI, respectively) have been characterized by a wide range of techniques, and their applicability for stimulated emission depletion (STED) microscopy has been tested. By cyano substitution a...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2014-12, Vol.118 (50), p.14662-14674
Main Authors: Kennes, Koen, Baeten, Yannick, Vosch, Tom, Sempels, Wouter, Yordanov, Stoyan, Stappert, Sebastian, Chen, Long, Müllen, Klaus, Hofkens, Johan, Van der Auweraer, Mark, Fron, Eduard
Format: Article
Language:English
Subjects:
Agglomeration
Cyano groups
Derivatives
Electron density
Excitation
Fluorescence
Microscopy
Stimulated emission
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Summary:Two new terrylenediimide (TDI) chromophores with cyano substituents in the bay and core area (BCN-TDI and OCN-TDI, respectively) have been characterized by a wide range of techniques, and their applicability for stimulated emission depletion (STED) microscopy has been tested. By cyano substitution an increase of the fluorescence quantum yield and a decrease of the nonradiative rate constant is achieved and attributed to a reduced charge-transfer character of the excited state due to a lower electron density of the TDI core. For BCN-TDI, the substitution in the bay area induces a strong torsional twist in the molecule which, similar to phenoxy bay-perylenediimide (PDI), has a strong effect on the fluorescence lifetime but appears to prevent the aggregation that is observed for OCN-TDI. The single-molecule photobleaching stability of BCN- and OCN-TDI is lower than that of a reference TDI without cyano substitution (C7-TDI), although less so for OCN-TDI. The photophysical properties of the excited singlet state are only slightly influenced by the cyano groups. The observed intense stimulated emission, the pump–dump–probe experiments, and STED single-molecule imaging indicate that STED experiments with the cyano-substituted TDIs are possible. However, because of aggregation and more efficient photobleaching, the performance of BCN- and OCN-TDI is worse than that of the reference compound without cyano groups (C7-TDI). Bay-substituted TDIs are less suitable for STED microscopy.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp5104577