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Mono‐ and Di(dimethylamino)styryl‐Substituted Borondipyrromethene and Borondiindomethene Dyes with Intense Near‐Infrared Fluorescence
Author(s) -
Yu YanHong,
Descalzo Ana B.,
Shen Zhen,
Röhr Holger,
Liu Quan,
Wang YanWei,
Spieles Monika,
Li YiZhi,
Rurack Knut,
You XiaoZeng
Publication year - 2006
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.200600042
Subject(s) - solvatochromism , chromophore , fluorescence , photochemistry , chemistry , excited state , protonation , absorption (acoustics) , infrared , solvent , ion , materials science , organic chemistry , optics , physics , nuclear physics , composite material
Abstract Four novel borondipyrromethene (BDP) and ‐diindomethene (BDI) dyes with one or two (dimethylamino)styryl extensions at the chromophore were synthesized and spectroscopically investigated. An X‐ray crystal structure shows that the extended auxochrome is virtually planar. All dyes thus display intense red/near infrared (NIR) absorption and emission. The (dimethylamino)styryl group induces a charge‐transfer character that entails bright solvatochromic fluorescence, which is only quenched with increasing solvent polarity according to the energy‐gap law. The dye with an additional dimethylanilino group at the meso position of BDP shows a remarkable switching of lipophilicity by protonation. Two dyes with an 8‐hydroxyquinoline ligand at the meso position display quenched emission in the presence of Hg 2+ or Al 3+ owing to electron transfer from the excited BDP to the complexed receptor. The BDI dye presents a pH indicator with bright fluorescence and extremely low fluorescence anisotropy.