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[ n ]‐Cyclo‐9,9‐dibutyl‐2,7‐fluorene ( n =4, 5): Nanoring Size Influence in Carbon‐Bridged Cyclo‐ para ‐phenylenes
Author(s) -
Sicard Lambert,
Lucas Fabien,
Jeannin Olivier,
Bouit PierreAntoine,
RaultBerthelot Joëlle,
Quinton Cassandre,
Poriel Cyril
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202002517
Subject(s) - fluorene , nanoring , cyclic voltammetry , ring (chemistry) , ring size , conjugated system , crystallography , chemistry , materials science , electrochemistry , photochemistry , nanotechnology , polymer , organic chemistry , electrode
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.