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Synthesis and Spectroscopic Properties of Fused‐Ring‐Expanded Aza‐Boradiazaindacenes
Author(s) -
Lu Hua,
Shimizu Soji,
Mack John,
Shen Zhen,
Kobayashi Nagao
Publication year - 2011
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.201000641
Subject(s) - bodipy , ring (chemistry) , fluorescence , chemistry , steric effects , absorption (acoustics) , fluorescence spectroscopy , structural isomer , absorption spectroscopy , spectroscopy , photochemistry , crystallography , stereochemistry , materials science , organic chemistry , quantum mechanics , composite material , physics
A series of fused‐ring‐expanded aza‐boradiazaindacene (aza‐BODIPY) dyes have been synthesized by reacting arylmagnesium bromides with phthalonitriles or naphthalenedicarbonitriles. An analysis of the structure–property relationships has been carried out based on X‐ray crystallography, optical spectroscopy, and theoretical calculations. Benzo and 1,2‐naphtho‐fused 3,5‐diaryl aza‐BODIPY dyes display markedly red shifted absorption and emission bands in the near‐IR region (>700 nm) due to changes in the energies of the frontier MOs relative to those of 1,3,5,7‐tetraaryl aza‐BODIPYs. Only one 1,2‐naphtho‐fused aza‐BODIPY of the three possible isomers is formed due to steric effects, and 2,3‐naphtho‐fused compounds could not be characterized because the final BF 2 complexes are unstable in solution. The incorporation of a N(CH 3 ) 2 group at the para ‐positions of a benzo‐fused 3,5‐diaryl aza‐BODIPY quenches the fluorescence in polar solvents and results in a ratiometric pH response, which could be used in future practical applications as an NIR “turn‐on” fluorescence sensor.