[n]-Cyclo-9,9-dibutyl-2,7-fluorene (n=4, 5): Nanoring Size Influence in Carbon-Bridged Cyclo-para-phenylenes |
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Authors: | Dr Lambert Sicard Fabien Lucas Dr Olivier Jeannin Dr Pierre-Antoine Bouit Dr Joëlle Rault-Berthelot Dr Cassandre Quinton Dr Cyril Poriel |
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Institution: | Univ Rennes, CNRS, ISCR-UMR 6226, 35000 Rennes, France |
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Abstract: | For the last ten years, ring-shaped π-conjugated macrocycles possessing radially directed π-orbitals have been subject to intense research. The electronic properties of these rings are deeply dependent on their size. However, most studies involve the flagship family of nanorings: the cyclo-para-phenylenes. We report herein the synthesis and study of the first examples of cyclofluorenes possessing five constituting fluorene units. The structural, optical and electrochemical properties were elucidated by X-ray crystallography, UV-vis absorption and fluorescence spectroscopy, and cyclic voltammetry. By comparison with a shorter analogue, we show how the electronic properties of 5]-cyclofluorenes are drastically different from those of 4]-cyclofluorenes, highlighting the key role played by the ring size in the cyclofluorene family. |
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Keywords: | cyclofluorene nanorings ring bridging ring size effect |
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