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Polysulfurated Pyrene‐Cored Dendrimers: Luminescent and Electrochromic Properties
Author(s) -
Gingras Marc,
Placide Virginie,
Raimundo JeanManuel,
Bergamini Giacomo,
Ceroni Paola,
Balzani Vincenzo
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801198
Subject(s) - dendrimer , photochemistry , dichloromethane , electrochromism , pyrene , cyclohexane , chemistry , fluorescence , redox , blueshift , absorption (acoustics) , materials science , polymer chemistry , inorganic chemistry , photoluminescence , organic chemistry , optics , optoelectronics , physics , electrode , solvent , composite material
We have synthesized a novel class of dendrimers, consisting of a polysulfurated pyrene core with appended poly(thiophenylene) dendrons ( PyG0 , PyG1 , and PyG2 , see Scheme 1), which exhibit remarkable photophysical and redox properties. In dichloromethane or cyclohexane solution they show a strong, dendron‐localized absorption band with a maximum at around 260 nm and a band in the visible region with a maximum at 435 nm, which can be assigned to the pyrene core strongly perturbed by the four sulfur substituents. The dendrimers exhibit a strong ( Φ =0.6), short‐lived ( τ =2.5 ns) core‐localized fluorescence band with maximum at approximately 460 nm in cyclohexane solution at 293 K. A strong fluorescence is also observed in dichloromethane solution at 293 K, in dichloromethane/chloroform rigid matrix at 77 K, and in the solid state (powder) at room temperature. The dendrimers undergo reversible chemical and electrochemical one‐electron oxidation with formation of a strongly colored deep blue radical cation. A second, reversible one‐electron oxidation is observed at more positive potential values. The photophysical and redox properties of the three dendrimers are finely tuned by the length of their branches. The strong blue fluorescence and the yellow to deep blue color change upon reversible one‐electron oxidation can be exploited for optoelectronic devices.