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Synthesis, One‐ and Two‐Photon Photophysical and Excited‐State Properties, and Sensing Application of a New Phosphorescent Dinuclear Cationic Iridium(III) Complex
Author(s) -
Xu WenJuan,
Liu ShuJuan,
Zhao Xin,
Zhao Ning,
Liu ZhiQiang,
Xu Hang,
Liang Hua,
Zhao Qiang,
Yu XiaoQiang,
Huang Wei
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202827
Subject(s) - phosphorescence , iridium , photochemistry , chemistry , excited state , absorption (acoustics) , acceptor , cationic polymerization , ligand (biochemistry) , absorption spectroscopy , materials science , fluorescence , atomic physics , physics , optics , polymer chemistry , organic chemistry , biochemistry , receptor , composite material , condensed matter physics , catalysis
A new phosphorescent dinuclear cationic iridium(III) complex ( Ir1 ) with a donor–acceptor–π‐bridge–acceptor–donor (DAπAD)‐conjugated oligomer ( L1 ) as a N^N ligand and a triarylboron compound as a C^N ligand has been synthesized. The photophysical and excited‐state properties of Ir1 and L1 were investigated by UV/Vis absorption spectroscopy, photoluminescence spectroscopy, and molecular‐orbital calculations, and they were compared with those of the mononuclear iridium(III) complex [Ir(Bpq) 2 (bpy)] + PF 6 − ( Ir0 ). Compared with Ir0 , complex Ir1 shows a more‐intense optical‐absorption capability, especially in the visible‐light region. For example, complex Ir1 shows an intense absorption band that is centered at λ =448 nm with a molar extinction coefficient ( ε ) of about 10 4 , which is rarely observed for iridium(III) complexes. Complex Ir1 displays highly efficient orange–red phosphorescent emission with an emission wavelength of 606 nm and a quantum efficiency of 0.13 at room temperature. We also investigated the two‐photon‐absorption properties of complexes Ir0 , Ir1 , and L1 . The free ligand ( L1 ) has a relatively small two‐photon absorption cross‐section ( δ max =195 GM), but, when complexed with iridium(III) to afford dinuclear complex Ir1 , it exhibits a higher two‐photon‐absorption cross‐section than ligand L1 in the near‐infrared region and an intense two‐photon‐excited phosphorescent emission. The maximum two‐photon‐absorption cross‐section of Ir1 is 481 GM, which is also significantly larger than that of Ir0 . In addition, because the strong BF interaction between the dimesitylboryl groups and F − ions interrupts the extended π‐conjugation, complex Ir1 can be used as an excellent one‐ and two‐photon‐excited “ON–OFF” phosphorescent probe for F − ions.