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CF 3 ‐Inspired Synthesis of Air‐Tolerant 9‐Phosphaanthracenes that Feature Fluorescence and Crystalline Polymorphs
Author(s) -
Ito Shigekazu,
Koshino Kota,
Mikami Koichi
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201701669
Subject(s) - trifluoromethyl , steric effects , chemistry , aryl , aromaticity , fluorescence , polar effect , crystal (programming language) , crystallography , crystal structure , stereochemistry , photochemistry , molecule , organic chemistry , alkyl , physics , quantum mechanics , computer science , programming language
9‐Phosphaanthracene (dibenzo[ b , e ]phosphorin, acridophosphine) has attracted interest as one of the heavier acenes. Herein, we demonstrate an efficient synthetic process that provides air‐tolerant 1,8‐bis(trifluoromethyl)‐9‐phosphaanthracenes. The sterically encumbered and electron‐withdrawing trifluoromethyl (CF 3 ) groups are quite advantageous not only to stabilize the intrinsically unstable heavier unsaturated phosphorus atom but also to facilitate construction of the phosphinine skeleton based on a putative increase in aromaticity. The isolated 9‐phosphaanthracenes allowed characterization of their fluorescence functionality and planar heteroanthracene frameworks. The crystal structures of 9‐phosphaanthracenes are remarkably dependent on the aryl substituents at the 10 position; anthryl‐substituted 9‐phosphaanthracene showed unique polymorphs that induced different‐colored crystals.