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Some quinolinol derivatives possessing suitable triplet state energy were examined to sensitize the luminescence of neodymium ion (Nd(III)) as coordinating ligands. Photosensitized luminescence in the near-infrared region of four neodymium(III) complexes: tris(8-quinolinolato)neodymium(III) ([Nd(q)3]), tris(5,7-dichloro-8-quinolinolato)neodymium(III) ([Nd(Clq)3]), tris(5,7-dibromo-8-quinolinolato)neodymium(III) ([Nd(Brq)3]) and tris(5,7-diiodo-8-quinolinolato)neodymium(III) ([Nd(Iq)3]), were observed by selective excitation of the ligand moieties in DMSO-d6. Highly efficient intramolecular energy transfer from the excited ligand moieties to the central Nd(III) ion was successfully achieved by using the halogenated ligands.

The relatively low efficiency of Nd (III) emission in organic media has been improved by 1) suppression of the radiationless transition process via vibrational excitation of the surrounding medium, 2) prevention of dipole-dipole nonradiative energy transfer processes via energy migration, 3) suppression of radiationless transition of D2O molecules in the vicinity of Nd (III) complexes (formation of twelve-coordinate Nd (III) complex with DMSO-d6), 4) allowance of electron transitions of Nd (III) by the introduction of asymmetric ligand field, 5) photosensitization by use of energy transfer from organic ligands. The luminescence of NMI) was observed for the first time in undeuterated acetone when Nd (III) was complexed with bis-perfluorooctylsulfonylamine (pos). As to the applications of luminescent Nd (III) complexes, developments of luminescent lanthanide polymers and EL device were successful.

Photosensitized luminescence in the near-infrared region of five low vibrational β–diketonato neodymium(III) complexes, tris(1,1,1,5,5,5-hexafluoroacetylacetonato)neodymium(III) (1), tris(4,4,5,5,5-pentafluoro-1-pentafluorophenyl-1,3-pentanedionato)neodymium(III) (2), tris(4,4,5,5,6,6,6-heptafluoro-1-pentafluorophenyl-1,3-hexanedionato)neodymium(III) (3), tris(4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-pentafluorophenyl-1,3-decanedionato)neodymium(III) (4), and tris[bis(pentafluorobenzoyl)methanato]neodymium(III) (5), were examined by the selective excitation of the ligand moieties in THF-d8. The intramolecular energy transfer efficiencies from the excited ligands to the central Nd(III) ion were determined and the order of 1

Coordination structures of neodymium(III) complexes with some β-diketones were investigated in terms of their correlations with emission efficiency in deuterated dimethylsulfoxide (DMSO-d6). The analysis of UV-vis spectra, 13C NMR, electrospray mass spectrometry (ES-MS) spectra, XANES and EXAFS analysis of tris(hexafluoroacetylacetonato)neodymium(III) complex, [Nd(hfa-H)3(H2O)2], and tris[bis(perfluorooctanoyl)methanato]neodymium(III), [Nd(pom-H)3], in DMSO indicated that the deuterated tris(hexafluoroacetylacetonato)neodymium(III), Nd(hfa-D)3, and deuterated tris[bis(perfluorooctanoyl)methanato]neodymium(III), Nd(pom-D)3, in DMSO-d6 should have a symmetrical, rigid and bulky shell composed of six inner-coordinating DMSO molecules and three weakly coordinating hfa-D and pom-D molecules. The improvement in the emission efficiency of the neodymium complexes with the low vibrational and weakly coordinating β-diketonates in DMSO-d6 was ascribed to their symmetrical rigid coordination structures, which should ...

A novel Nd3+ complex, Nd(POA-D)3, with asymmetric ligands (POA: perfluorooctanoylacetic acid), was synthesized in order to enhance the transition probability in its f–f transition by reducing symmetry of the ligand field around Nd3+. This complex gives the 2.5 times higher oscillator strength of the hypersensitive transition in methanol-d4 than the corresponding symmetrical complex, Nd(POM-D)3 (POM: bisperfluorooctanoylmethane). The Stark splitting of the emitting level of Nd(POA-D)3 was observed and the Judd-Ofelt analysis gave a large Ω2 value, clearly showing the asymmetric environment around Nd3+. 13C NMR analysis, molecular orbital and molecular mechanics calculations and EXAFS analysis suggest that the asymmetric environment achieved in Nd(POA-D)3 is ascribed mainly to the asymmetric distribution of electrons on the coordinating O atoms. The higher absorption coefficient of Nd(POA-D)3 leads to 1.86 times stronger emission than Nd(POM-D)3 when measured at the common concentration and conditions. It is stressed that introduction of asymmetric ligands is a promising way for promoting emission of Nd3+ in solutions when coupled with replacement of C–H bonds with C–D and C–F in the ligands.

Organic electroluminescence devices using a neodymium(III) complex as an emitting layer were fabricated. The cell structure of glass substrate/indium–tin–oxide/N,N′-diphenyl-N,N′-di(m-tolyl)-benzidine/tris(dibenzoylmethanato)(monobathophenanthroline)neodymium(III) complex/tris(8-quinolinolato)aluminum(III) complex/Mg:Ag was employed. Sharp near-infrared emission bands assigned to f–f transitions of neodymium ion were obtained at dc bias voltage of over 15 V.

The room temperature near-infrared electroluminescence(EL) was observed from organic EL devices using the ytterbium(III) [Yb(III)] complex as an emitter over 15 V, though there was no spectral overlap between the lowest triplet state of ligand and the emissive level of Yb(III) ion needed for the intramolecular energy transfer. The EL emission with a peak at 985 nm was assigned to the 2F5/2 → 2F7/2 transition of Yb(III) ion.

Remarkable luminescence of neodymium ion (Nd(III)) complexed with 8-quinolinol derivatives containing halogen atoms was successfully observed in organic solution under visible light irradiation via photosensitization. Introduction of halogen atoms in the ligands led to enhancement of the luminescence.

Photosensitized luminescence of Nd3+ in solution was successfully observed for the first time by coordinating the metal cation with deuterated 4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-pentafluorophenyl-1,3-decanedione as a ligand with a low vibrational chromophore.