title: Mono- and di(dimethylamino)styryl-substituted borondipyrromethene and borondiindomethene dyes with intense near-infrared fluorescence.
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 Hg2+ or Al3+ 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.
authors: Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China.
authors: Yan-Hong
authors: YH
authors: Yu
authors: Ana B
authors: AB
authors: Descalzo
authors: Zhen
authors: Z
authors: Shen
authors: Holger
authors: H
authors: Röhr
authors: Quan
authors: Q
authors: Liu
authors: Yan-Wei
authors: YW
authors: Wang
authors: Monika
authors: M
authors: Spieles
authors: Yi-Zhi
authors: YZ
authors: Li
authors: Knut
authors: K
authors: Rurack
authors: Xiao-Zeng
authors: XZ
authors: You