Yong-Hui Zhou

Iridium(III) phosphorescent complexes with dual stereogenic centers: single crystal, electronic circular dichroism evidence and circularly polarized luminescence properties

Iridium complexes with a chiral metal center and chiral carbons, Λ/Δ-(dfppy)2Ir(chty-R) and Λ/Δ-(dfppy)2Ir(chty-S), were synthesized and characterized. These isomers have the same steady-state photophysical properties, and obvious offsets in ECD spectra highlight both the chiral sources. Each enantiomeric couple shows mirror-image CPL bands with a dissymmetry factor in the order of 10-3.

Photoluminescence properties of dinuclear lanthanide complexes in visible and near-infrared region

Several dinuclear lanthanide complexes of Ln2(HTH)6TPPHZ (Ln=Eu, Sm, Er, Nd, Yb, Ho; TPPHZ=Tetrapyrido (3,2-a:2′,3′-c:3′,2″-h:2′″,3′″-j) phenazine; HTH=4,5,5,6,6,6-heptafluroro-1-(2-thienyl)hexane-1,3-dione were synthesized and their photoluminescence properties were investigated. After ligand-mediated excitation, all the complexes showed the characteristic luminescence of the corresponding Ln(III) ions in the visible and NIR regions attributed to energy transfer from the ligands to the metal center. For Eu2(HTH)6TPPHZ complex, the quantum efficiency was calculated as 9.6% with the major 5D0 lifetime (477.86 μs) by the equation ϕ=τobs/τR, where τobs was observed luminescence lifetime and τR was radiative (or natural) lifetime (5 ms), and 14.9% with air-equilibrated aqueous [Ru(bpy)3](II)·2Cl− solution as a standard sample (ϕstd=2.8%), in CH2Cl2 solution at room temperature.

Synthesis and photoluminescence of a dendritic europium complex with carbazole moieties

Abstract A novel dendritic europium complex containing grafted carbazole units as functional peripheries was synthesized and characterized. The Forster energy transfer from the peripheries of carbazole units to β-diketonate as well as from the ligands to the central Eu(III) ions in the complex was demonstrated. Under the excitation of carbazole units and β-diketonate, characteristic red emission peaks at 612 nm with four shoulders due to the Eu(III) ion transition of 5D0 → 7FJ (J=0–4) were observed for the complex.

Syntheses and photoluminescence properties of rhenium(I) complexes based on dipyrido[3,2-a:2′,3′-c]phenazine derivatives with carbazole moiety

Four rhenium(I) complexes ReL1–ReL4 based on dipyrido[3,2-a:2′,3′-c]phenazine (L1) and derivatives L2-L4 ligands (L2: 10,13-dibromodipyrido[3,2-a:2′,3′-c]phenazine, L3: 10-bromo-13-carbazolyl-dipyrido[3,2-a:2′,3′-c]phenazine, L4: 10,13-dicarbazolyldipyrido[3,2-a:2′,3′-c]phenazine) were synthesized and characterized. The Re(I) complexes ReL1–ReL4 show photoluminescent emissions at 556, 582, 637 and 662 nm, respectively, assigned to d (Re)→ ∗ (diimine) MLCT phosphorescence in CH2Cl2 solution. The carbazole containing complexes ReL3 and ReL4, as compared to ReL1, exhibit higher luminescence. These observations imply that modification of diimine rhenium(I) carbonyl complexes with carbazole moiety would lead to efficient phosphorescent properties.