title: Synthesis, one- and two-photon photophysical and excited-state properties, and sensing application of a new phosphorescent dinuclear cationic iridium(III) complex.
abstract: A new phosphorescent dinuclear cationic iridium(III) complex (Ir1) with a donor-acceptor-π-bridge-acceptor-donor (D-A-π-A-D)-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 B-F 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.
authors.affiliation: Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046, PR China.
authors.forename: Wen-Juan
authors.initials: WJ
authors.lastname: Xu
authors.forename: Shu-Juan
authors.initials: SJ
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Hang
authors.initials: H
authors.lastname: Xu
authors.forename: Hua
authors.initials: H
authors.lastname: Liang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: Xiao-Qiang
authors.initials: XQ
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
mesh_terms: D000042:Absorption; D060326:Chemistry Techniques, Synthetic; D005461:Fluorine / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D049408:Luminescent Agents / Q000138:chemical synthesis* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D055620:Optical Phenomena; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D017785:Photons
chemical_list: D049408:Luminescent Agents; D009942:Organometallic Compounds; D005461:Fluorine; D007495:Iridium